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The greatest and most
influential of Plato's students was Aristotle,
who established his own school at Athens. Although his writing career probably
began with the production of quasi-Platonic dialogues, none of them have
survived. Instead, our knowledge of Aristotle's doctrines must be derived from
highly-condensed, elliptical works that may have been lecture notes from his
teaching at the Lyceum. Although not intended for publication, these texts
reveal a brilliant mind at work on many diverse topics.
Philosophically, the
works of Aristotle reflect his gradual departure from the teachings of Plato
and his adoption of a new approach. Unlike Plato, who delighted in abstract
thought about a supra-sensible realm of forms, Aristotle was intensely concrete
and practical, relying heavily upon sensory observation as a starting-point for
philosophical reflection. Interested in every area of human knowledge about the
world, Aristotle aimed to unify all of them in a coherent system of thought by
developing a common methodology that would serve equally well as the procedure for
learning about any discipline.
For Aristotle, then,
logic is the instrument (the "organon") by means of which we come to
know anything. He proposed as formal rules for correct reasoning the basic
principles of the categorical
logic that was universally accepted by Western philosophers until the
nineteenth century. This system of thought regards assertions of the
subject-predicate form as the primary expressions of truth, in which features
or properties are shown to inhere in individual substances. In every discipline
of human knowledge,then, we seek to establish the things of some sort have
features of a certain kind.
Aristotle further supposed
that this logical scheme accurately represents the true nature of reality. Thought,
language, and reality are all isomorphic, so careful consideration of what we
say can help us to understand the way things really are. Beginning with simple
descriptions of particular things, we can eventually assemble our information
in order to achieve a comprehensive view of the world.
The initial book in
Aristotle's collected logical works is the Categories,
an analysis of predication generally. It begins with a distinction among three
ways in which the meaning of different uses of a predicate may be related to
each other: homonymy,
synonymy, and paronymy (in some translations, "equivocal,"
"univocal," and "derivative"). Homonymous uses of a
predicate have entirely different explanations, as in "With all that
money, she's really loaded," and "After all she had to drink, she's
really loaded." Synonymous uses have exactly the same account, as in
"Cows are mammals," and "Dolphins are mammals." Paronymous
attributions have distinct but related senses, as in "He is healthy,"
and "His complexion is healthy." (Categories
1) It is important in every case to understand how this use of a predicate
compares with its other uses.
So long as we are
clear about the sort of use we are making in each instance, Aristotle proposed
that we develop descriptions of individual things that attribute to each
predicates (or categories)
of ten different sorts. Substance
is the most crucial among these ten, since it describes the thing in terms of
what it most truly is. For Aristotle, primary substance is just the individual
thing itself, which cannot be predicated of anything else. But secondary
substances are predicable, since they include the species and genera to which
the individual thing belongs. Thus, the attribution of substance in this
secondary sense establishes the essence of each particular thing.
The other nine
categories—quantity, quality, relative, where, when, being in a position,
having, acting on, and being affected by—describe the features which
distinguish this individual substance from others of the same kind; they admit
of degrees and their contraries may belong to the same thing. (Categories
4) Used in combination, the ten kinds of predicate can provide a
comprehensive account of what any individual thing is. Thus, for example: Chloë
is a dog who weighs forty pounds, is reddish-brown, and was one of a litter of
seven. She is in my apartment at 7:44 a.m. on June 3, 1997, lying on the sofa,
wearing her blue collar, barking at a squirrel, and being petted. Aristotle
supposed that anything that is true of any individual substance could, in
principle, be said about it in one of these ten ways.
Another of
Aristotle's logical works, On
Interpretation, considers the use of predicates in combination with
subjects to form propositions
or assertions, each of which is either true or false. We usually determine the
truth of a proposition by reference to our experience of the reality it
conveys, but Aristotle recognized that special difficulties arise in certain
circumstances.
Although we grant
(and can often even discover) the truth or falsity of propositions about past
and present events, propositions about the future seem problematic. If a
proposition about tomorrow is true (or false) today, then the future event it
describes will happen (or not happen) necessarily; but if such a proposition is
neither true nor false, then there is no future at all. Aristotle's solution
was to maintain that the disjunction is necessarily true today even though
neither of its disjuncts is. Thus, it is necessary that either tomorrow's event
will occur or it will not, but it is neither necessary that it will occur nor
necessary that it will not occur. (On Interpretation 9)
Aristotle's treatment of
this specific problem, like his more general attempt to sort out the nature of
the relationship between necessity
and contingency in On
Interpretation 12-13, is complicated by the assumption that the structure
of logic models the nature of reality. He must try to explain not just the way
we speak, but the way the world therefore must be.
Finally, in the Prior
Analytics and Posterior Analytics, Aristotle offered a detailed account
of the demonstrative reasoning required to substantiate theoretical knowledge.
Using mathematics as a model, Aristotle presumed that all such knowledge must
be derived from what is already known. Thus, the process of reasoning by syllogism employs a
formal definition of validity
that permits the deduction of new truths from established principles. The goal
is to provide an account of why things happen the way they do, based solely
upon what we already know.
In order to achieve genuine
necessity, this demonstrative science must be focussed on the essences rather than the
accidents of things, on what is "true of any case as such,"
rather than on what happens to be "true of each case in fact." It's
not enough to know that it rained today; we must be able to figure out the
general meteorological conditions under which rain is inevitable. When we
reason from necessary universal
and affirmative
propositions about the essential features of things while assuming as little as
possible, the resulting body of knowledge will truly deserve the name of
science.
Applying the
principles developed in his logical treatises, Aristotle offered a general
account of the operation of individual substances in the natural world. He drew
a significant distinction between things of two sorts: those that move only
when moved by something else and those that are capable of moving themselves.
In separate treatises, Aristotle not only proposed a proper description of
things of each sort but also attempted to explain why they function as they do.
Aristotle considered
bodies and their externally-produced movement in the Physics.
Three crucial distinctions determine the shape of this discussion of physical
science. First, he granted from the outset that, because of the difference in
their origins, we may need to offer different accounts for the functions of natural
things and those of artifacts. Second, he insisted that we clearly distinguish
between the basic material and the form which jointly constitute the
nature of any individual thing. Finally, Aristotle emphasized the difference
between things as they are and things considered in light of their ends or purposes.
Armed with these
distinctions, Aristotle proposed in Physics
II, 3 that we employ four very different kinds of explanatory principle
{Gk. aition [aition]} to the question of why a
thing is, the four
causes:
The material
cause is the basic stuff out of which the thing is made. The material cause
of a house, for example, would include the wood, metal, glass, and other
building materials used in its construction. All of these things belong in an
explanation of the house because it could not exist unless they were present in
its composition.
The formal cause
{Gk. eidos [eidos]} is the pattern or essence
in conformity with which these materials are assembled. Thus, the formal cause
of our exemplary house would be the sort of thing that is represented on a
blueprint of its design. This, too, is part of the explanation of the house,
since its materials would be only a pile of rubble (or a different house) if
they were not put together in this way.
The efficient
cause is the agent or force immediately responsible for bringing this matter and that form
together in the production of the thing. Thus, the efficient cause of the house
would include the carpenters, masons, plumbers, and other workers who used
these materials to build the house in accordance with the blueprint for its
construction. Clearly the house would not be what it is without their
contribution.
Lastly, the final
cause {Gk. teloV [télos]} is the end or purpose for
which a thing exists, so the final cause of our house would be to provide
shelter for human beings. This is part of the explanation of the house's
existence because it would never have been built unless someone needed it as a
place to live.
Causes of all four sorts
are necessary elements in any adequate account of the existence and nature
of the thing, Aristotle believed, since the absence or modification of any one
of them would result it the existence of a thing of some different sort.
Moreover, an explanation that includes all four causes completely captures the
significance and reality of the thing itself.
Notice that the four
causes apply more appropriately to artifacts than to natural objects. The rise
of modern science resulted directly from a rejection of the Aristotelean notion
of final causes in particular. Still, the scheme works so well for artifacts
that we often find ourselves attributing some purpose even to the apparently
pointless events of the natural world.
In many applications
the formal, efficient, and final causes tend to be combined in a single being
that designs and builds the thing for some specific purpose. Thus, the
fundamental differentiation in the Aristotelean world turns out to be between
inert matter on the one hand and intelligent agency on the other. As we shall
soon see, this provides a natural explanation for the functions of animate
natural organisms.
As for things that
appear to arise by pure chance, Aristotle argued that since the purposeful
origination described by the four causes is the normal order of the world,
these instances must either be things that should have had some cause but
happen to lack it or (more likely) things that actually do have causes of which
we are simply unaware. The craft evident in the manufacture of artifacts, he
believed, is evidence for the purposive character of nature, and it shares the
same necessity, even though we are sometimes ignorant of its internal
operations. (Physics II, 8)
Although I would be
hard-pressed to come up with a final cause for the existence of the mosquito
that is now biting me, for example, Aristotle supposed that there must
ultimately be some explanation for its present existence and activity. Many
generations of Western philosophers, especially those concerned with
reconciling Christian doctrine with philosophy, would explicitly defend a
similar view.
Aristotle considered
the most fundamental features of reality in the twelve books of the Metafusikh
(Metaphysics).
Although experience of what happens is a key to all demonstrative knowledge,
Aristotle supposed that the abstract study of "being qua
being" must delve more deeply, in order to understand why things happen
the way they do. A quick review of past attempts at achieving this goal reveals
that earlier philosophers had created more difficult questions than they had
answered: the Milesians
over-emphasized material causes; Anaxagoras
over-emphasized mind; and Plato got bogged down in the theory of forms.
Aristotle intended to do better.
Although any disciplined
study is promising because there is an ultimate truth to be discovered, the
abstractness of metaphysical
reasoning requires that we think about the processes we are employing even
as we use them in search of that truth. As always, Aristotle assumed that the
structure of language and logic naturally mirrors the way things really are.
Thus, the major points of each book are made by carefully analyzing our
linguistic practices as a guide to the ultimate nature of what is.
It is reasonable to
begin, therefore, with the simplest rules of logic, which embody the most
fundamental principles applying to absolutely everything that is:
The Law of Non-Contradiction in
logic merely notes that no assertion is both true and false, but applied to
reality this simple rule entails that nothing can both
"be . . . " and "not
be . . . " at the same time, although we will of
course want to find room to allow for things to change. Thus, neither strict Protagorean relativism
nor Parmenidean
immutability offer a correct account of the nature of reality. (Metaphysics IV 3-6)
The Law of Excluded Middle in
logic states the necessity that either an assertion or its negation must be
true, and this entails that there is no profound indeterminacy in the realm of
reality. Although our knowledge of an assertion may sometimes fall short of
what we need in order to decide whether it is true or false, we can be sure
that either it or its negation is true. (Metaphysics IV 7-8)
In order to achieve its
required abstract necessity, all of metaphysics must be constructed from
similar principles. Aristotle believed this to be the case because metaphysics
is concerned with a genuinely unique subject matter. While natural science
deals with moveable, separable things and mathematics focusses upon immoveable,
inseparable things, metaphysics (especially in its highest, most abstract
varieties) has as its objects only things that are both immoveable and
separable. Thus, what we learn in metaphysics is nothing less than the
immutable eternal nature, or essence, of individual
things.
In the central books
of the Metaphysics, Aristotle tried to develop an adequate analysis of
subject-predicate judgments. Since logic and language rely heavily upon the copulative
use of "is," careful study of these uses should reveal the genuine
relationship that holds between substances and their features. Of course, Plato
had already offered an
extended account of this relationship, emphasizing the reality of the
abstract forms rather than their material substratum.
But Aristotle argued
that the theory of forms is seriously flawed: it is not supported by good
arguments; it requires a form for each thing; and it is too mathematical. Worst
of all, on Aristotle's view, the theory of forms cannot adequately explain the
occurrence of change. By identifying the thing with its essence, the theory
cannot account for the generation of new substances. (Metaphysics
VII) A more reasonable position must differentiate between matter and form and
allow for a dynamic relation between the two.
Aristotle therefore
maintained that each individual substance is a hylomorphic composite
involving both matter and form together. Ordinary predication, then, involves paronymously
attributing an abstract universal of a concrete individual, and our experience
of this green thing is more significant than our apprehension of the form of
greenness. This account, with its emphasis on the particularity of individual
substances, provided Aristotle with a firm foundation in practical experience.
Aristotle also
offered a detailed account of the dynamic process of change. A potentiality {Gk. dunamiV [dynamis]} is either the passive capacity of a
substance to be changed or (in the case of animate beings) its active capacity
to produce change in other substances in determinate ways. An actuality {Gk. energeia [energeia]} is just the realization of one of these
potentialities, which is most significant when it includes not merely the
movement but also its purpose. Becoming, then, is the process in which
the potentiality present in one individual substance is actualized through the
agency of something else which is already actual. (Metaphysics
IX) Thus, for Aristotle, change of any kind requires the actual existence of
something which causes the change.
The higher truths of what
Aristotle called "theology" arise from an application of these
notions to the more purely speculative study of being qua being. Since
every being is a composite whose form and matter have been brought together by
some cause, and since there cannot be infinitely many such causes, he concluded
that everything that happens is ultimately attributable to a single universal
cause, itself eternal and immutable. (Metaphysics XII 6) This self-caused "first
mover," from which all else derives, must be regarded as a mind, whose
actual thinking is its whole nature. The goodness of the entire universe,
Aristotle supposed, resides in its teleological unity as the will of a single
intelligent being.
According to
Aristotle, every animate being is a living thing which can move itself only
because it has a soul.
Animals and plants, along with human beings, are more like each other than any
of them are like any inanimate object, since each of them has a soul. Thus, his
great treatise on psychology, On The Soul,
offers interconnected explanations for the functions and operations of all
living organisms.
All such beings, on
Aristotle's view, have a nutritive soul which initiates and guides their most
basic functions, the absorption of food, growth, and reproduction of its kind.
All animals (and perhaps some plants) also have a sensitive soul by means of
which they perceive features of their surroundings and move in response to the
stimuli this provides. Human beings also possess (in addition to the rest) a
rational soul that permits representation and thought. (On the
Soul II 2)
Notice that each living
thing has just one soul, the actions of which exhibit some degree of nutritive,
sensitive, and/or rational functioning. This soul is the formal, efficient, and
final cause of the existence of the organism; only its material cause resides
purely in the body. Thus, all of the operations of the organism are to be
explained in terms of the functions of its soul.
Sensation is the passive capacity for the soul to be changed
through the contact of the associated body with external objects. In each
variety of sensation, the normal operations of the appropriate organ of sense
result in the soul's becoming potentially what the object is in actuality.
Thus, without any necessary exchange of matter, the soul takes on the form of
the object: when I feel the point of a pin, its shape makes an impression on my
finger, conveying this form to my sensitive soul (resulting in information).
(On
the Soul II 5)
Thought is the more active process of engaging in the
manipulation of forms without any contact with external objects at all. Thus,
thinking is potentially independent of the objects of thought, from which it
abstracts the form alone. Even the imagination, according to Aristotle,
involves the operation of the common sense without stimulation by the sensory
organs of the body. Hence, although all knowledge must begin with information
acquired through the senses, its results are achieved by rational means.
Transcending the sensory preoccupation with particulars, the soul employs the
formal methods of logic to cognize the relationships among abstract forms. (On the
Soul III 4)
Desire is the origin of movement toward some goal. Every
animate being, to some degree, is capable of responding to its own internal
states and those of its external environment in such a way as to alleviate the
felt absence or lack of some pleasure or the felt presence of some pain. Even
actions taken as a result of intellectual deliberation, Aristotle supposed, produce
motion only through the collateral evocation of a concrete desire. (On the
Soul III 10)
Aristotle applied
the same patient, careful, descriptive approach to his examination of moral philosophy in the
Eqikh Nikomacoi
(Nicomachean
Ethics). Here he discussed the conditions under which moral
responsibility may be ascribed to individual agents, the nature of the virtues
and vices involved in moral evaluation, and the methods of achieving happiness
in human life. The central issue for Aristotle is the question of character or
personality — what does it take for an individual human being to be a good
person?
Every activity has a
final cause, the good at which it aims, and Aristotle argued that since there
cannot be an infinite regress of merely extrinsic goods, there
must be a highest good at which all human activity ultimately aims. (Nic.
Ethics I 2) This end of human life could be called happiness (or living
well), of course, but what is it really? Neither the ordinary notions of
pleasure, wealth, and honor nor the philosophical theory of forms provide an
adequate account of this ultimate goal, since even individuals who acquire the
material goods or achieve intellectual knowledge may not be happy.
According to Aristotle,
things of any variety have a characteristic function that they are properly
used to perform. The good for human beings, then, must essentially involve the
entire proper function of human life as a whole, and this must be an activity
of the soul that expresses genuine virtue or excellence. (Nic.
Ethics I 7) Thus, human beings should aim at a life in full conformity
with their rational natures; for this, the satisfaction of desires and the
acquisition of material goods are less important than the achievement of virtue. A happy
person will exhibit a personality appropriately balanced between reasons and
desires, with moderation
characterizing all. In this sense, at least, "virtue is its own
reward." True happiness can therefore be attained only through the
cultivation of the virtues that make a human life complete.
Ethics is not merely
a theoretical study for Aristotle. Unlike any intellectual capacity, virtues of
character are dispositions
to act in certain ways in response to similar situations, the habits of
behaving in a certain way. Thus, good conduct arises from habits that in turn
can only be acquired by repeated action and correction, making ethics an
intensely practical discipline.
Each of the virtues is a
state of being that naturally seeks its mean {Gk. mesoV [mesos]} relative to us. According to
Aristotle, the virtuous habit of action is always an intermediate state between
the opposed vices of excess and deficiency: too much and too little are always
wrong; the right kind of action always lies in the mean. (Nic.
Ethics II 6) Thus, for example:
with
respect to acting in the face of danger,
courage {Gk.
andreia [andreia]} is a mean between
the excess of rashness and the deficiency of cowardice;
with respect to the enjoyment of pleasures,
temperance
{Gk. swfrosunh [sophrosúnê]} is a mean between
the excess of intemperance and the deficiency of insensibility;
with respect to spending money,
generosity is a mean between
the excess of wastefulness and the deficiency of stinginess;
with respect to relations with strangers,
being friendly is a mean between
the excess of being ingratiating and the deficiency of being surly;
and
with respect to self-esteem,
magnanimity
{Gk. megaloyucia [megalopsychia]} is a
mean between
the excess of vanity and the deficiency of pusillanimity.
Notice that the
application of this theory of virtue requires a great deal of flexibility:
friendliness is closer to its excess than to its deficiency, while few human
beings are naturally inclined to undervalue pleasure, so it is not unusual to
overlook or ignore one of the extremes in each of these instances and simply to
regard the virtue as the opposite of the other vice.
Although the analysis may
be complicated or awkward in some instances, the general plan of Aristotle's
ethical doctrine is clear: avoid extremes of all sorts and seek moderation in
all things. Not bad advice, surely. Some version of this general approach
dominated Western culture for many centuries.
Because ethics is a
practical rather than a theoretical science, Aristotle also gave careful consideration
to the aspects of human nature involved in acting and accepting moral responsibility.
Moral evaluation of an action presupposes the
attribution of responsibility to a human agent. But in certain circumstances,
this attribution would not be appropriate. Responsible action must be
undertaken voluntarily,
on Aristotle's view, and human actions are involuntary under two distinct
conditions: (Nic. Ethics III 1)
First, actions that
are produced by some external force (or, perhaps, under an extreme duress from
outside the agent) are taken involuntarily, and the agent is not responsible
for them. Thus, if someone grabs my arm and uses it to strike a third person, I
cannot reasonably be blamed (or praised) morally for what my arm has done.
Second, actions
performed out of ignorance are also involuntary. Thus, if I swing my arm for
exercise and strike the third party who (unbeknownst to me) is standing nearby,
then again I cannot be held responsible for having struck that person. Notice
that the sort of ignorance Aristotle is willing to regard as exculpatory is
always of lack of awareness of relevant particulars. Striking other people
while claiming to be ignorant of the moral rule under which it is wrong to do
so would not provide any excuse on his view.
As we'll soon see,
decisions to act voluntarily rely upon deliberation about the choice among
alternative actions that the individual could perform. During the deliberative
process, individual actions are evaluated in light of the good, and the best
among them is then chosen for implementation. Under these conditions, Aristotle
supposed, moral actions are within our power to perform or avoid; hence, we can
reasonably be held responsible for them and their consequences. Just as with health
of the body, virtue of the soul is a habit that can be acquired (at least in
part) as the result of our own choices.
Although the virtues
are habits of acting or dispositions to act in certain ways, Aristotle
maintained that these habits are acquired by engaging in proper conduct on
specific occasions and that doing so requires thinking about what one does in a
specific way. Neither demonstrative knowledge of the sort employed in science
nor aesthetic judgment of the sort applied in crafts are relevant to morality.
The understanding
{Gk. dianoia [diánoia]} can only explore the
nature of origins of things, on Aristotle's view, and wisdom {Gk. sofia [sophía]} can only trace the demonstratable
connections among them.
But there is a
distinctive mode of thinking that does provide adequately for morality,
according to Aristotle: practical intelligence or prudence {Gk. fronhsiV [phrónêsis]}. This faculty alone comprehends the
true character of individual and community welfare and applies its results to
the guidance of human action. Acting rightly, then, involves coordinating our
desires with correct thoughts about the correct goals or ends.
This is the function of
deliberative reasoning: to consider each of the many actions that are within
one's power to perform, considering the extent to which each of them would
contribute to the achievement of the appropriate goal or end, making a
deliberate choice to act in the way that best fits that end, and then
voluntarily engaging in the action itself. (Nic.
Ethics III 3) Although virtue is different from intelligence, then, the
acquisition of virtue relies heavily upon the exercise of that intelligence.
But doing the right
thing is not always so simple, even though few people deliberately choose to
develop vicious habits. Aristotle sharply disagreed with Socrates's belief that
knowing what is right
always results in doing it. The great enemy of moral conduct, on
Aristotle's view, is precisely the failure to behave well even on those
occasions when one's deliberation has resulted in clear knowledge of what is
right.
Incontinent agents
suffer from a sort of weakness
of the will {Gk. akrasia [akrásia]} that prevents them
from carrying out actions in conformity with what they have reasoned. (Nic.
Ethics VII 1) This may appear to be a simple failure of intelligence,
Aristotle acknowledged, since the akratic individual seems not to draw the
appropriate connection between the general moral rule and the particular case
to which it applies. Somehow, the overwhelming prospect of some great pleasure
seems to obscure one's perception of what is truly good. But this difficulty,
Aristotle held, need not be fatal to the achievement of virtue.
Although incontinence is
not heroically moral, neither is it truly vicious. Consider the difference
between an incontinent person, who knows what is right and aims for it but is
sometimes overcome by pleasure, and an intemperate person, who purposefully
seeks excessive pleasure. Aristotle argued that the vice of intemperance is
incurable because it destroys the principle of the related virtue, while
incontinence is curable because respect for virtue remains. (Nic.
Ethics VII 8) A clumsy archer may get better with practice, while a
skilled archer who chooses not to aim for the target will not.
In a particularly
influential section of the Ethics, Aristotle considered the role of
human relationships in general and friendship {Gk. filia [philia]} in particular as a vital element in the good
life.
For without friends no one would
choose to live, though he had all other goods.
Differentiating between
the aims or goals of each, he distinguished three kinds of friendships that we
commonly form. (Nic. Ethics VIII 3)
A friendship for
pleasure comes into being when two people discover that they have common
interest in an activity which they can pursue together. Their reciprocal
participation in that activity results in greater pleasure for each than either
could achieve by acting alone. Thus, for example, two people who enjoy playing
tennis might derive pleasure from playing each other. Such a relationship lasts
only so long as the pleasure continues.
A friendship
grounded on utility, on the other hand, comes into being when two people can
benefit in some way by engaging in coordinated activity. In this case, the
focus is on what use the two can derive from each other, rather than on any
enjoyment they might have. Thus, for example, one person might teach another to
play tennis for a fee: the one benefits by learning and the other benefits
financially; their relationship is based solely on the mutual utility. A
relationship of this sort lasts only so long as its utility.
A friendship for the
good, however, comes into being when two people engage in common activities
solely for the sake of developing the overall goodness of the other. Here,
neither pleasure nor utility are relevant, but the good is. (Nic. Ethics
VIII 4) Thus, for example, two people with heart disease might play tennis
with each other for the sake of the exercise that contributes to the overall
health of both. Since the good is never wholly realized, a friendship of this
sort should, in principle, last forever.
Rather conservatively
representing his own culture, Aristotle expressed some rather peculiar notions
about the likelihood of forming friendships of these distinct varieties among
people of different ages and genders. But the general description has some
value nevertheless, especially in its focus on reciprocity. Mixed
friendships—those in which one party is seeking one payoff while the other
seeks a different one—are inherently unstable and prone to dissatisfaction.
Aristotle rounded
off his discussion of ethical living with a more detailed description of the
achievement of true happiness. Pleasure is not a good in itself, he argued,
since it is by its nature incomplete. But worthwhile activities are often
associated with their own distinctive pleasures. Hence, we are rightly guided
in life by our natural preference for engaging in pleasant activities rather
than in unpleasant ones.
Genuine happiness lies in
action that leads to virtue, since this alone provides true value and not just
amusement. Thus, Aristotle held that contemplation is the highest form of moral
activity because it is continuous, pleasant, self-sufficient, and complete. (Nic.
Ethics X 8) In intellectual activity, human beings most nearly approach
divine blessedness, while realizing all of the genuine human virtues as well.
Since friendship is
an important feature of the good life and virtuous habits can be acquired
through moral education and legislation, Aristotle regarded life within a moral
community as a vital component of human morality. Even in the Ethics, he
had noted that social order is presumed by the general concept of justice. (Nic. Ethics
V 2)
Properly considered,
justice is concerned with the equitability or fairness in interpersonal
relations. Thus, Aristotle offered an account of distributive justice that made
allowances for the social rectification of individual wrongs. Moreover, he
noted that justice in the exchange of property requires careful definition in
order to preserve equity. The broader concept of political justice, however, is
to be recognized only within the context of an entire society. Thus, it
deserves separate treatment in a different treatise.
That treatise is
Aristotle's Politics, a comprehensive examination of the origins and
structure of the state. Like Plato, Aristotle supposed that the need for a
division of labor is the initial occasion of the formation of a society, whose
structure will be modelled upon that of the family. (Politics
I 2) But Aristotle (preferring the mean) declined to agree with Plato's
notion of commonly held property and argued that some property should be held
privately.
Aristotle also drew
a sharper distinction between morality and politics than Plato had done.
Although a good citizen is a good person, on Aristotle's view, the good person
can be good even independently of the society. A good citizen, however, can
exist only as a part of the social structure itself, so the state is in some
sense prior to the citizen.
Depending upon the
number of people involved in governing and the focus of their interests,
Aristotle distinguished six kinds of social structure in three pairs:
A state with only
one ruler is either a monarchy or a tyrrany;
A state with several
rulers is either an aristocracy or an oligarchy; and
A state in which all
rule is either a polity or a democracy.
In each pair, the first sort of state is one in which the rulers are concerned
with the good of the state, while those of the second sort are those in which
the rulers serve their own private interests. (Politics
III 7)
Although he believed
monarchy to be the best possible state in principle, Aristotle recognized that
in practice it is liable to degenerate into the worst possible state, a
tyrrany. He therefore recommended the formation of polity, or constitutional
government, since its degenerate form is the least harmful of the bad kinds of
government. As always, Aristotle defended the mean rather than run the risk of
either extreme.
Another sharp
contrast between Plato and Aristotle emerges in the latter's Poetics,
and analysis of the effects of dramatic art. Aristotle, unlike his teacher,
supposed that the extravagant representation of powerful emotions is beneficial
to the individual citizen, providing an opportunity for the cathartic release
of unhealthy feelings rather than encouraging their development.
Tragedy in particular
arouses our fear and pity, as we recognize the inherent flaw of the tragic
hero. Having seen the outcome in dramatic form, we are less likely to commit
similar acts of pride, Aristotle argued, so the literary arts have a direct
benefit to human society. This provides no grounds for a Platonic notion of
censorship of the arts.
Although their
relative reputations often varied widely, the philosophies of Plato and
Aristotle continued to exert a powerful influence throughout the following
centuries. Even now, it is often suggested that Western thinkers are invariably
either Platonic or Aristotelean. That is, each of us is inclined either toward
the abstract, speculative, intellectual apprehension of reality, as Plato was,
or toward the concrete, practical, sensory appreciation of reality, as
Aristotle was. The differences between the two approaches may be too
fundamental for argumentation or debate, but the coordination or synthesis of
the two together is extremely difficult, so choice may be required.
Certainly the philosophy of
the Middle Ages, to which we will devote the remainder of this semester,
exhibits some form of this division. As Christian thinkers tried to find ways
of accomodating their religious doctrines to the tradition of Greek philosophy,
some version of Plato and some version of Aristotle were significant factors in
their development.
The great golden age
of Athenian philosophy, encompassing Socrates,
Plato, and Aristotle
only lasted for about a hundred years. In the centuries that followed,
changes in the political and cultural climate of the ancient world tended to
discourage many varieties of philosophical thinking. The Macedonians under
Philip and Alexander founded a Greek empire, which was later conquered by the
Romans. Although the general culture of this "Hellenistic" period
remained Greek in spirit, political power was vested in a highly centralized
state, established and maintained primarily through extensive applications of
military force. The (sometime) Athenian tradition of participatory government
disappeared as individual citizens were excluded from significantly shaping the
social structure of their lives.
Hellenistic philosophers,
therefore, devoted less attention than had Plato and Aristotle to the
speculative construction of an ideal state that would facilitate the
achievement of a happy life. Instead, the ethical thinkers of this later period
focussed upon the life of the individual, independently of the society as a
whole, describing in detail the kinds of character and action that might enable
a person to live well despite the prevailing political realities. In general,
we might say, such philosophers tried to show how we should live when
circumstances beyond our control seem to render pointless everything we try to
accomplish. The Hellenistic schools of philosophy, then, exhibit less
confidence and propose solutions less radical than their Athenian predecessors
had in the golden era.
The ancient atomists (Leucippus and Democritus) had
already worked out a systematic description of the natural world comprising
many particular material particles, whose mechanical interactions account for
everything that happens. In the Hellenistic period, attention turned to the
consequences of such a view for the conduct of human life.
Epicurus
and his followers pointed out (in the Principle
Doctrines, for example) that since the indestructible atoms that
constitute the material world move, swerve, and collide entirely by chance,
everything that happens in the universe lies outside the reach of direct human
control. (Notice how this position projects Hellenistic political impotence
onto the natural world.) Human life is, therefore, essentially passive: all we
can do is to experience what goes on, without supposing ourselves capable of
changing it. Even so, Epicurus held that this sort of life may be a good one,
if the experiences are mostly pleasant ones.
Thus, in the Letter
to Menoeceus, Epicurus held that the proper goal of human life is to
achieve mental ease {Gk. ataraxia [ataraxia]} and freedom from
pain. All of our sensual
desires are natural and their satisfaction is to be desired, since
satiation is always a pleasure but frustrated desire is a mild pain. Material
goods are worthwhile only to the extent that possessing them contributes to the
achievement of peace. What is more, Epicurus held that we have no reason to
complain of the fact that human life must come to an end. Since death results
in the annihilation of the personality, he argued, it cannot be experienced and
is thus nothing to be feared. Thus, Epicureanism was long ago summarized as the
view recommending that we "relax, eat, drink, be merry." (Luke 12:19-20)
The parody is
accurate as far as it goes: Epicurus did suppose that a successful life is one
of personal fulfillment and the attainment of happiness within this
life. But the philosophical Epicureans were less confident than many of their
later imitators about the prospects for achieving very much pleasure in
ordinary life. They emphasized instead the mental peace that comes from
accepting whatever happens without complaint or struggle. Notice again that
this is a reasonable response to a natural world and social environment that do
not provide for effective individual action.
The Roman philosopher Lucretius defended a
similar set of theses, including both atomism in general and an Epicurean
devotion to tranquillity in his philosophical poem De Rerum Naturae (On
the Nature of Things).
A rival school of
philosophy in Athens was that of the Stoics. As originally
developed by Zeno of
Citium and Chrysippus,
stoicism offered a comprehensive collection of human knowledge encompassing
formal logic, physical study of the natural world, and a thoroughly
naturalistic explanation of human nature and conduct. Since each human being is
a microcosm of the
universe as a whole, they supposed, it is possible to employ the same methods
of study to both life and nature equally.
In the Hellenistic
period, Epictetus tersely noted the central features of a life
thusly lived according to nature in his Encheiridion
(Manual). Once again, the key is to understand how little of what
happens is within our control, and stoicism earns its reputation as a stern way
of life with recommendations that we accept whatever fate brings us without
complaint, concern, or feeling of any kind. Since family, friends, and material
goods are all perishable, Epictetus held, we ought never to become attached to
them. Instead, we treat everything and everyone we encounter in life as a
temporary blessing (or curse), knowing that they will all pass away from us
naturally.
This seems cold and harsh
advice indeed, but it works! If, indeed, we form no attachments and care about
nothing, then loss will never disturb the tranquillity and peace of our lives.
This way of life can be happy even for a slave like Epictetus. But later Roman
Stoics like Seneca
and Marcus Aurelius
made clear in their lives and writings that it has merits even for those who
are better-off.
Another school of
Hellenistic philosophy illustrates yet again the prevailing lack of confidence
that life in this era inspired. The skeptics supposed that
the possibility of human knowledge is severely limited in scope and
application.
Skepticism began
with Pyrrho of Elis,
who taught that apart from the sketchy information provided by the senses, we
have no genuine knowledge of the nature of things. Unable to achieve certainty
about the general structure of the world, human beings should often practice
suspension of judgment, which is the only rational response to situations in
which they are ignorant. This course naturally results in a nearly total lack
of activity, which Pyrrho took to be equivalent to peace of mind. Although he
wrote nothing, Pyrrho exerted a powerful influence on succeeding generations
through his disciple, Timon
of Philius and members of the later Academy.
Centuries later, Sextus Empiricus wrote
a history of skeptical philosophy, the Outlines of
Pyrrhonism, and used the Pyrrhonian approach to criticize the
pretensions of other schools of thought. He made it clear that the skeptical
challenge to traditional theories
of knowledge arises from an unusually strict definition of knowledge
itself. If we can only be said properly to know what is absolutely certain or
beyond doubt, then
very little indeed will be known. Although it was widely ignored in his own
time, the work of Sextus was instrumental in the modern revival of
interest in skeptical philosophy.
Despite (or because
of) the gloomy prospects held forward by these schools of philosophy, the later Hellenistic period
also produced significant movement toward the consolidation of the older Greek
philosophical tradition with the middle-eastern religions of Judaism and
Christianity.
Philo Judaeus, for example,
tried to develop a comprehensive view embracing both Plato
and Judaism. This was no easy task, since the traditional religion of scripture
was concrete and historically-rooted, while Plato's philosophy was extremely
abstract and general. But since he supposed that the same deity had inspired
human awareness of truth in both contexts, Philo maintained that synthesis must
be possible. He interpreted the religious texts allegorically, finding in their
structure clues and hints of the deeper philosophical truth. (Allegory is a
dangerously powerful tool; it often permits or even encourages the 'discovery'
of nearly any doctrine you like even within the most straightforwardly prosaic
texts. Perhaps "Green Eggs and Ham" is a deeply subversive expression
of communist political ideology, while "Bert and Ernie" encourage a
homosexual lifestyle, and . . . .) For Philo, the goodness
of the one transcendent god is expressed through the divine word {Gk. logos [logos]}, which is the organizing principle that
accounts for everything in the cosmos.
The Christian church
fathers were not far behind. The earliest among them either regarded philosophy
as a source of heretical theology (Irenaeus) or offered general
anti-intellectual tirades against the power of human reason (Tertullian). But
Justin Martyr carefully noted the natural affinities between the emerging
Christian theology and the traditions of thought deriving from Plato, and
Origen explicitly endeavored to combine the two in a single system. This path
of development continued for centuries, reaching its peak in Gregory of Nyssa
and Ambrose, who was the teacher of Augustine.
The version of
Platonic philosophy that came to be incorporated into the theology of the
middle ages, however, had rather little to do with the thought of Plato
himself. It was, instead, derived from the quasi-mystical writings of Plotinus. In an
aphoristic book called the Enneads,
Plotinus used Plato's fascination with the abstract forms of things as
the starting-point for a comprehensive metaphysical view of the cosmos.
According to
Plotinus, the form of the Good is the transcendent source of everything in the
universe: from its central core other forms emanate outward, like the ripples
in a pond, losing measures of reality along the way. Thus, although the early emanations retain much
of the abstract beauty of their source, those out on the fringes of the cosmos
have very little good left in them. Nevertheless, Plotinus supposed that
careful examination of anything in the world could be used to lead us toward
the central reality, if we use the information it provides as the basis for our
reasoning about its origins in something more significant. In principle,
progressive applications of this technique will eventually bring us to
contemplation of the Good itself and knowledge of the nature of the universe.
But since the Good is both
the cause of the universe and the source of its moral quality for Plotinus,
philosophical study is a redemptive activity. Achievement of mystical union
with the cause of the universe promises to provide us not only with knowledge
but also with the true elements of virtue as well. It was this neoplatonic philosophy
that the Christians found so well-suited to their own theological purposes.
Once the Good is identified with the god of scripture, the details work
themselves out fairly naturally. Thus, we'll find notions of this sort to be a
popular feature of medieval philosophy.
Having devoted
extensive attention to the development of philosophy among the ancient Greeks,
we'll now cover more than a
millenium of Western thought more briefly. The very name
"medieval" (literally, "the in-between time") philosophy
suggests the tendency of modern thinkers to skip rather directly from Aristotle
to the Renaissance. What seemed to justify that attitude was the tendency of
philosophers during this period to seek orthodoxy as well as truth.
Nearly all of the medieval
thinkers—Jewish, Christian, and Muslim—were pre-occupied with some version of
the attempt to synthesis philosophy with religion. Early on, the neoplatonism philosophy
of Plotinus seemed
to provide the most convenient intellectual support for religious doctrine. But
later in the medieval era, thanks especially to the work of the Arabic-language
thinkers, Aristotle's metaphysics gained a wider acceptance. In
every case, the goal was to provide a respectable philosophical foundation for
theological positions. In the process, much of that foundation was effectively
absorbed into the theology itself, so that much of what we now regard as
Christian doctrine has its origins in Greek philosophy more than in the
Biblical tradition.
The first truly
great medieval philosopher was Augustine of
Hippo, a North African rhetorician and devotee of Manichaeanism who
converted to Christianity under the influence of Ambrose and devoted his career
to the exposition of a philosophical system that employed neoplatonic elements in
support of Christian orthodoxy. The keynote of Augustine's method is "Credo
ut intellegiam" ("I believe in order that I may
understand"), the notion that human reason in general and philosophy in
particular are useful only to those who already have faith.
Thus, for example,
Augustine simply rejected the epistemological criticisms mounted by the Academic skeptics.
Even if it were true that I am mistaken about nearly everything that I suppose
to be true, he argued, one inescapable truth will remain: "Si fallor,
sum" ("If I am mistaken, I exist"). [This doctrine is an
interesting anticipation of Descartes's later attempt to establish knowledge on the
phrase "Cogito
ergo sum".] Upon this foundation, Augustine believed it possible
to employ human faculties of sense and reason effectively in the pursuit of
substantive knowledge of the world.
Although Augustine
was significantly influenced by the moral philosophy of Cicero, he generally
argued that the Stoics
were excessively optimistic in their assessment of human nature. One of
Augustine's central contributions to the development of Christian theology was
his heavy emphasis on the reality of human evil. Each one of us, he believed,
is sinful by nature, and the account of his own life provided in the early portions
of the Confessions makes it clear that he did not suppose himself to
be an exception.
If, as Augustine
certainly believed, the world and everything in it is the creation of a
perfectly good god, then how can the human beings who constitute so prominent a
part of that creation be inherently evil? Like Plato
and Plotinus, but
unlike the Manichaeans,
Augustine now argued that evil is not anything real, but rather is merely the
absence of good. Creation of human beings who have the freedom to decide how to
act on their own, he maintained, is so vital a part of the divine plan for the
cosmos that it outweighs the obvious consequence that we nearly always choose
badly.
But if human beings begin
with original sin and are therefore inherently evil, what is the point of
morality? Augustine held that the classical attempts to achieve virtue by
discipline, training, and reason are all boud to fail. Thus, the redemptive
action of god's grace alone offers hope. Again using his own life as an
example, Augustine maintained that we can do nothing but wait for god to work
with us in the production of a worthwhile life. (Our happiness never enters
into the picture.)
That there is indeed
a god, Augustine proved in fine Platonic fashion: Begin with the fact that we
are capable of achieving mathematical knowledge, and remember that, as Plato
demonstrated, this awareness transcends the sensory realm of appearances
entirely. Our knowledge of eternal mathematical truths thus establishes the
immateriality and immortality of our own rational souls. (So far, the argument is
straight out of Plato's Phaedo.)
Augustine further
argued that the eternal existence of numbers and of the mathematical relations
that obtain among them requires some additional metaphysical support. There
must be some even greater being that is the eternal source of the reality of
these things, and that, of course, must be god. Thus, Augustine endorses a Plotinian concept of
god as the central core from which all of reality emanates.
But notice that if the
truths of mathematics depend for their reality upon the creative activity of
the deity, it follows that god could change them merely by willing them to be
different. This is an extreme version of a belief known as voluntarism, according
to which 2 + 3 = 5 remains true only so long as god wills it to be so. We
can still balance our checkbooks with confidence because, of course, god
invariably wills eternally. But in principle, Augustine held that even necessary truths are
actually contingent upon the exercise of the divine will.
This emphasis on the
infinite power of god's will raises a significant question about our own
capacity to will and to act freely. If, as Augustine supposed, god has infinite
power and knowledge of every sort, then god can cause me to act in particular
ways simply by willing that I do so, and in every case god knows in advance in
what way I will act, long before I even contemplate doing so. From this, it
would seem naturally to follow that I have no will of my own, cannot act of my
own volition, and therefore should not be held morally responsible for what I
do. Surely marionettes are not to be held accountable for the deeds they
perform with so many strings attached.
Augustine's answer to this
predicament lies in his analysis of time. A god who is eternal must stand
wholly outside the realm of time as we know it, and since god is infinitely
more real than we are, it follows that time itself does not exist at the level
of the infinitely real. The passage of time, the directionality of knowledge,
and all temporal relations are therefore nothing more than features of our
limited minds. And it is within these limitations, Augustine supposed, that we
feel free, act on our volitions, and are responsible for what we do. God's
foreknowledge, grounded outside the temporal order, has no bearing on the
temporal nature of our moral responsibility. Once again, a true understanding
of the divine plan behind creation resolves every apparent conflict.
The End of Hellenism
European culture
developed only very slowly after the collapse of the Roman Empire in 427.
Theological controversies and narrow-minded defenses of traditional doctrine
and practice were the sole pre-occupations of educated clergy. During these
"Dark Ages," concern with the necessities of life and
anti-intellectual sentiment in the church did little to encourage philosophical
speculation. Although many nameless individuals worked to preserve the written
tradition of what had gone before, there were few genuine high points in our
philosophical history for a few hundred years.
An anonymous Christian
writer of the fifth or sixth century (later designated as the pseudo-Dionysius)
distinguished between two distinct approaches that human beings might take in
their efforts to understand god. The via positiva is the method of
reasoning analogically from the perceived nature of existing objects through
successive layers of causal emanations until we
arrive at some conception of the divine essence from which all flows. The via
negativa, on the other hand, denies the literal truth of any comparison
between natural things and god and relies instead upon mystical consciousness
as the only possible source of genuine knowledge. Thus, in good neoplatonic fashion,
god's unity and goodness are contrasted with the degenerate plurality and evil
of the created order.
As classical
scholarship began to wane, preservation of the philosophical tradition required
capable translation of the central works from Greek into Latin. This labor was the
great contribution of Boethius,
whose translation of Aristotle's logical works provided the standard set of
Latin terms for the logic of the middle ages. Moreover, Boethius's Commentary
on the Isagoge of Porphyry focussed
medieval attention on a metaphysical problem that arises from the simple fact
that two or more things may share a common feature. The President of the United
States and my youngest child, for example, have something in common, since they
are both human beings.
The problem of universals asks the
metaphysical question of what in reality accounts for this similarity between
distinct individual substances. When we predicate of each substance the name of
the species to which they both belong, what kinds of entities are truly
involved? If the species itself is a third independently existing
entity, then we must postulate the existence of a separate sphere of
abstract beings like the
Platonic forms. If, on the other hand, what is shared by both substances is
nothing more than the
name of the species, then our account of resemblances seems grounded on
little more than linguistic whim. The difficulty of providing a satisfactory
account of the predication of shared features provoked intense debate
throughout the middle ages. As we'll soon see, the variety
of positions adopted with respect to this metaphysical issue often served as a
litmus test of academic loyalties.
Since his own life lead to
imprisonment and execution, Boethius also gave careful consideration to the
intellectual and ethical principles of living well. In De
consolatione philosophiae (The
Consolation of Philosophy), he maintained that commitment to rational
discourse and decision-making is vital to the successful human life, even
though it offers little prospect of avoiding the personal disasters fate holds
for many of us.
During the ninth century, a British
thinker named John
Scotus Erigena applied the via negativa along with Aristotelean
logic in order to develop a more carefully systematic description of the nature
of reality in the neoplatonic view. Noting the crucial distinction between
active (or creative) beings on the one hand and what they produce (the created)
on the other, Erigena proposed that all of reality be comprehended under four
simple categories:
·
The only creating uncreated being is god,
of which we can know nothing except its role as the central source of all.
·
Creating created beings
are the Platonic forms (including human souls) by whose mediation the divine
produces the world.
·
Ordinary things are uncreating created
beings, the distant emanations that constitute the natural world as we perceive
it.
·
Finally, uncreating uncreated must once
again be god alone.
Thus, Erigena completes
the logically tidy picture with a fourth category of existence that contradicts
yet must be identified with the first, emphasizing the view that only mystical
consciousness can even try to grasp the nature of god. Each human being is a microcosm in whom
analogues of these four fundamental elements combine to produce a dynamic whole
whose existence and activity mirror those of the universe.
Few of Erigena's
contemporaries appreciated the subtlety and logic of this view, however.
Subordinating dialectical reasoning to the presumed dictates of revealed
religion at every opportunity, many medieval writers defended and even
encouraged the kind of deliberate ignorance that results from an unwillingness
to question prevailing opinion. The Socratic spirit nearly disappeared.
The end of the "Dark
Ages" in the philosophical tradition is clearly marked by the work of Anselm of
Canterbury. Explicitly rejecting the anti-intellectual spirit
of preceding centuries, Anselm devoted great care to his cultivation of the
Augustinian theology of "faith seeking understanding." In the
process, Anselm initiated an entirely new way of demonstrating the existence of
god.
Reflecting on the
text of Psalm 14 ("Fools say in their hearts, 'There is no god.'") in
his Proslogion, Anselm proposed a proof of divine reality that has come
to be known as the
Ontological Argument. The argument takes the Psalmist quite literally by
supposing that in virtue of the content of the concept of god there is a
contradiction involved in the denial of god's existence.
Anselm supposes that
in order to affirm or deny anything about god, we must first form in our minds
the appropriate concept, namely the concept of "that than which nothing
greater can be conceived" (in Latin, "aliquid quod maius non
cogitari potest"). Having done so, we have in mind the idea of god.
But of course nothing about reality usually follows from what we have in mind,
since we often think about things that do not (or even cannot) actually exist.
In the case of this special concept, however, Anselm argued that what we can
think of must in fact exist independently of our thinking of it.
Suppose the
alternative: if that than which nothing greater can be conceived existed only
in my mind and not in reality, then I could easily think of something else
which would in fact be greater than this (namely, the same thing existing in
reality as well as in my mind), so that what I originally contemplated turns
out not in fact to be that than which nothing greater can be conceived. Since
this is a contradiction, only a fool would believe it. So that than which
nothing greater can be conceived (that is, god) must exist in reality as well
as in the mind.
Something certainly seems
fishy about this argument. It is extraordinary to suppose that merely thinking
about something makes it so. But it turns out to be difficult to specify
precisely what the problem is with Anselm's reasoning here.
Early objections
(like those of the monk Gaunilo) focussed on the notion of conceivability at
work here, proposing a similarly absurd argument for the reality of the most
perfect conceivable island. But Anselm's claim is that only the concept of god
unites all of the perfections under the umbrella of absolute unsurpassibility.
What is more, Anselm supposed that existence is an essential feature of god's
nature, and many philosophers have pointed out that existence is not a
feature that could properly be included in the essence of any object. But the
restatement of the argument in Proslogion 3 seems to suggest that it is
necessary, not merely contingent, existence that must be predicated of the
deity, and this version may avoid the conceivability issue altogether.
Perhaps the real
difficulty with this argument has less to do with conceivability than with the
idea of perfection in general, with its attendant notion of unsurpassability.
"The person taller than whom no other person is now living" must
truly exist in reality as well as in our minds (provided that there is at least
one living person), but it is not clear that "the person taller than whom
no other person can ever live" exists as a coherent concept even in the
understanding, much less in reality. In similar fashion, it may be that there
is no concept corresponding to the words, "that than which nothing greater
can be conceived," giving the ontological argument no foundation.
Despite all of these
difficulties, Anselm's effort has continued to find sympathetic supporters for
nearly a millenium. Remember that within the Augustinian approach, the
demonstration is not really intended as a proof that will persuade unbelievers
to convert. Rather, it occurs within the context of prayerful meditation, as
one element in the believer's ongoing pursuit of faith seeking understanding.
Anselm's patient and
rational approach to philosophical issues and his willingness to engage in
debate with other thinkers who disagreed with the positions he defended were
greatly influential on western culture. They helped give rise to the
development of scholasticism,
a process of intergenerational cooperation engendered by shared appeal to a
common tradition of rational argumentation.
No everyone
participated happily in this process, of course; Christian anti-inellectualism
continued to flourish, as is clear in the writings of Peter Damian during the
eleventh century. Damian condemned the use of dialectic for both secular and
theological purposes, and argued that since human reason is so insignificant in
comparison with the power of faith, the untrained and ignorant are bound to be
wiser than the educated and thoughtful.
Many Christian thinkers
disagreed, however, and their efforts to comprehend those who had gone before
and to develop an intellectual tradition within the church were well served by
the Book of Sentences (Libri Quatuor Sententiarum) (1158)
compiled by Peter
Lombard. An appropriate textbook for an era during which few copies of any
book could be made generally available for student use, the Sentences
simply quoted the opinions of earlier philosophers with respect to a variety of
questions. Rarely commenting on these ancient materials, Lombard simply reported
the conflicting views of the authorities issue by issue, leaving adjudication
between them to the active participation of the reader. This helped to foster a
framework of debate in which the basic positions could be clearly defined and
new arguments in their criticism or defense easily developed.
One of the issues
that most plagued scholastic philosophers during this period was the problem of universals.
What is the ontological
status of the species to which many things commonly belong? Realists, following in
the tradition of Plato, maintained that each universal is an entity in its
own right, existing independently of the individual things that happen to
participate in it. Nominalists,
on the other hand, pursuing a view nearer that of Aristotle,
held that only particular things exist, since the universal is nothing more
than a name that applies to certain individual substances.
The difficulties
with each position are clear. Nominalism seems to suggest that whether or not
two things share a feature depends solely upon our accidental decision whether
or not to call them by the same name. Realism, on the other hand, introduces a
whole range of special abstract entities for the simple purpose of accounting
for similarities that particular things exhibit. In the medieval spirit of
disputation, each side found it easier to attack its opponents' views than to defend
its own. But the most brilliant disputant of the twelfth century invented a
third alternative that avoided the difficulties of both extremes.
French logician Peter Abelard
proposed that we ground the genuine similarities among individual things
without reifying their universal features, by predicating general terms in
conformity with concepts abstracted from experience. This view, which came to
be known as conceptualism,
denies the reality of universals as separate entities yet secures the
objectivity of our application of general terms. Although only individual
things and their particular features truly exist, we effectively employ our
shared concepts as universals. This resolution of the traditional problem of
universals gained wide acceptance for several centuries, until doubts about the
objectivity and
reality of such mental entities as concepts came under serious question.
In the centuries during
which scholastic philosophy emerged among the Christians, Muslim thinkers in
the Arab world that spanned Persia, North Africa, and Iberia dealt with many of
the same issues. Like their European counterparts, Arabs tried to work out an
appropriate synthesis of philosophy with theology, struggling as the Christians
had with the relationship between faith and reason and the effort to provide an
account of human nature that left room for the hope of immortality. But since
their culture had preserved both the ancient texts and classical learning to a
greater degree, the Arab thinkers had access to a wealth of material from the
Hellenistic world of which the Latin philosophers of the dark ages were
ignorant.
Thus, for example,
the neoplatonic philosophy
of the first great Arab thinker, al-Kindi set the tone
for many generations of Islamic synthesizers. His near-contemporary al-Farabi not only made
use of the logical treatises of Aristotle
(which even the Christians knew) but also employed arguments for the existence
of god based upon those in the later books of Aristotle's Metaphysics as
well. Designed to provide a rational foundation for orthodox monotheism, many
of these arguments would make their way into the Christian tradition only in
the thirteenth century.
Not everyone appreciated
such applications of the philosophical tradition, however. Several generations
later, al-Ghazali
wrote a lengthy treatise called Tahafut al-Falasifah (The Incoherence
of Philosophers), in which he used logical methods derived from the
philosophical tradition to generate puzzles and contradictions, thereby
undermining confidence in the power of human reason and encouraging reliance on
an unreasoned faith instead. Even in the more scientific culture of the Muslim
world, philosophical speculation remained suspect for centuries.
Among the
philosophers who flourished in the eastern portion of the Islamic territory
during the eleventh
century, the Persian Ibn
Sina (whom the Christians called "Avicenna" in Latin) was the
most subtle and sophisticated. Although his view of the world relied heavily on
the familiar neoplatonic emanations, Ibn Sina had learned of the Aristotelean
system in his medical studies and from the work of al-Farabi, and he tried to
combine elements from both sources in a comprehensive account of reality.
All human awareness
begins with knowledge of the self, which can be acquired entirely without the
aid of the senses, through the active power of the "agent intellect"
which is the human mind. But since the essential quality of human thinking
cannot be realized without some prior existing cause, contemplation of our own
reality as thinking things leads naturally to awareness of the existence of
something else. In addition to the merely contingent beings of the created
order, then, there must also be a necessary being, god, who is prior to all the
rest.
God, then, is the central
reality from which all else must be derived. Respecting the power of god and
emphasizing the regularity of the natural order, Ibn Sina maintained that all
of the genuinely causal connections that link the central core, through its
successive emanations, to its final outcomes in the material world, must
themselves be perfectly necessary. Since the cosmos is a single unified whole,
everything that happens does so as it must; what appear to us to be the local
causes of particular events are nothing more than the occasions for our
awareness of what happens. Its ultimate origin is always god.
A century later, in the
lively Andalusian community at the western extreme of Arab influence, another
great Islamic philosopher placed even greater emphasis on the work of Aristotle.
Ibn Rushd
("Averroës" in Latin) wrote so many analyses and explanations of
Aristotelean works that he became known throughout Europe simply as "The
Commentator." It was almost exclusively as a result of his labors in
translating and explicating the Aristotelean corpus that the Greek philosopher
came to exert a lasting influence on the Western culture.
Devoted to the teachings of
Aristotle, Ibn Rushd often disagreed explicitly with his Islamic predecessors.
Writing his Tahafut al-Tahafut against Ghazali, he argued that
application of reason to philosophical problems can lead to genuine knowledge
of the truth independently of revelation. Against Ibn Sina and the neoplatonic
emanation theory, he maintained that efficient causation is a genuine feature
of relationships among created things, although the first mover remains the
ultimate source of all motion. Following Aristotle's view of the individual
human being as a hylomorphic
composite of soul and matter, Ibn Rushd
could only promise immortality through absorption into the greater whole of the
universal intellect.
Medieval Judaism
provided another significant stream of philosophical speculation. Social,
personal, and intellectual freedom for Jews was greater in the Islamic world of
that era than among the anti-Semitic Christians of Europe, who often simply
regarded Jewish thinkers as Arabs. Though born in Egypt, Gaon Saadiah, for
example, spent his most active years studying the Talmud in Baghdad. Most
medieval Jewish philosophers dealt with the familiar difficulty of trying to
synthesize philosophy with religion, but their neoplatonism was often
infused with a greater degree of emphasis on the mystical apprehension of
reality.
The greater breadth
of learning achieved by Jewish scholars often resulted in the combination of
particular elements derived from diverse philosophical sources. Although Ibn
Gabirol accepted Plotinus's
view of god as the center from which all created reality emanates, for example,
he also defended a hylomorphic
account of ordinary objects and proposed a physiological explanation for human
conduct and morality. Ibn
Daud made an even more explicit use of Aristotelean metaphysics.
The most widely
respected of the medieval Jewish philosophers was Moses Maimonides, whose
patient codification of centuries of commentary on Jewish law in the Mishnah
Torah earned him a place of honor among Jews in the saying, "From
Moses until Moses, there was no one like Moses." From the neoplatonic
philosophical tradition, he took the central vision of god as the sole source
of all genuine knowledge, of which human reason can only hope to gain a remote
glimpse.
Thus, in the Moreh
Nevukhim (Guide to the Perplexed) (1190) Maimonides suggested that
philosophical reasoning about ultimate matters is neither necessary nor even
helpful for most ordinary people, who would be better advised to rely upon
faith. For members of the educated elite, who are more capable of understanding
abstract philosophical reasoning, however, there may be at least some hope of
success. Balancing the philosophical and prophetic traditions, Maimonides
himself provided Aristotelean arguments for the existence of god, Biblical
evidence for the creation of the universe, and a carefully-crafted synthesis of
reasons for the possibility of a divinely-produced immortality for embodied
human beings.
During the thirteenth century,
Christian Europe finally began to assimilate the lively intellectual traditions
of the Jews and Arabs. Translations of ancient Greek texts (and the fine Arabic
commentaries on them) into Latin made the full range of Aristotelean philosophy
available to Western thinkers. This encouraged significant modifications of the
prevalent neoplatonic
emanation-theory. Robert
Grosseteste, for example, followed Ibn Sina in emphasizing
the causal regularity evidenced by our experience of the world, and Siger of Brabant used
the commentaries of Ibn
Rushd as the basis for his thoroughly Aristotelean views.
In England, Roger Bacon initiated a
national tradition of empiricist
thinking. Bacon proposed a systematic plan for supplementing our meager
knowledge of the external world. Although he granted that consultation of the
ancient authorities has some value, Bacon argued that it is even more important
to employ individual experience for experimental confirmation. In coming
generations, this reliance upon experimental methods would become vital for the
development of modern science.
When universities
developed in the great cities of Europe during this era, rival clerical orders
within the church began to battle for political and intellectual control over
these centers of educational life. At Paris during the thirteenth century, two
of the newest orders found their most capable philosophical representatives.
The Franciscans,
founded by Francis of Assisi in 1209, were initially the philosophical
conservatives. As their leader in mid-century, Bonaventure defended a
traditional Augustine's theology, blending only a little of Aristotle
in with the more traditional neoplatonic elements. In later generations,
however, members of
this order were leaders in the anti-rationalistic attacks that brought an
effective end to scholastic traditions.
The Dominican order,
founded by Dominic in 1215, on the other hand, placed great emphasis on the use
of reason and made extensive use of Aristotelean materials. Thus, their finest
expositor was Aquinas,
whose works became definitive of Dominican (and, eventually, of Catholic)
philosophy. Later Dominicans, like Savonarola, were more likely to pursue
political power than philosophical truth.
After studying in
Paris with Alexander of Hales, Bonaventure taught and
wrote extensively, leading his Franciscans in the measured defense of the scholastic synthesis
of Platonic philosophy with Christian doctrine. Like Anselm,
Bonaventure supposed that truth can emerge from rational argumentation only
when the methods of philosophy are illuminated by religious faith. Thus,
efforts to prove god's existence naturally begin with religious conviction
itself, as an internal evidence of creaturely dependence on the deity.
Bonaventure held
that the notion of an eternal material order is contradictory, so that reason
itself supports the Christian doctrine of creation. Since god is the central
being from which all else then emanates, every
creature—including even human beings with sinful natures—may be regarded as a
footprint (Lat., vestiguum) of the divine reality. Thus, in the language
of Christian doctrine, we are made in god's image and likeness; or, as Plato
might have put it, we participate (partly) in the Form of the Good. Even matter itself is
endowed by the creator with seminal urges by means of which effective causation
can proceed from within.
Despite his general
commitment to neoplatonic
principles and rejection of Aristotelean metaphysics, Bonaventure did accept
the notion of human nature as a hylomorphic composite.
Although the human soul is indeed the form of the human body, Bonaventure
maintained however, it is capable, with the help of god, of continuing to exist
after the death of the body. Thus, as always, he accepted the thought of
Aristotle only so far as it could be made to conform to his preconceptions
about Christian doctrine. As we'll see next time, one of his contemporaries at
Paris used a very different approach.
The most profoundly
influential of all the medieval philosophers was the Dominican Thomas Aquinas,
whose brilliant efforts in defence of Christian theology earned him a
reputation as "the angelic teacher." His willingness to employ
rational argumentation generally and the metaphysical and epistemological
teachings of Aristotle in particular marked a significant departure
from the neoplatonic/Augustinian tradition that had dominated so much of the
middle ages. Aquinas showed the church that it was possible to incorporate many
of the "new" teachings of "the Philosopher" (Aristotle)
without falling into the mistaken excesses of "the Commentator" (Ibn
Rushd), and this became the basis for a lasting synthesis.
For Aquinas, theology is a
science in which careful application of reason will yield the demonstrative
certainty of theoretical
knowledge. Of course it is possible to accept religious teachings from
revealed sources by faith alone, and Aquinas granted that this always remains
the most widely accessible route to Christian orthodoxy. But for those whose
capacity to reason is well-developed, it is always better to establish the most
fundamental principles on the use of reason. Even though simple faith is enough
to satisfy most people, for example, Aquinas believed it possible, appropriate,
and desirable to demonstrate the existence of god by rational means.
Anselm's Ontological Argument is
not acceptable, Aquinas argued, since we are in fact ignorant of the divine
essence from which it is presumed to begin. We cannot hope to demonstrate the
necessary existence of a being whose true nature we cannot even conceive by
direct or positive means. Instead, Aquinas held, we must begin with the sensory
experiences we do understand and reason upward from them to their origin in
something eternal. In this vein, Aquinas presented his own "Five Ways" to
prove the existence of god.
The first three of
these ways are all variations of the Cosmological Argument.
The first way is an argument from motion, derived fairly directly from Aristotle's Metaphysics:
1.
There is something moving.
2.
Everything that moves is put into motion by
something else.
3.
But this series of antecedent movers cannot reach
back infinitely.
4.
Therefore, there must be a first mover (which is
god).
The first premise is
firmly rooted in sensory experience, and the second is based on accepted
notions about potentiality and actuality. In defence of the third, Aquinas
noted that if the series were infinite then there would be no first, and hence
no second, or third, etc. The second way has the same structure, but
begins from experience of an instance of efficient causation, and the third
way relies more heavily upon a distinction between contingent and necessary
being.
In all of its forms,
the Cosmological Argument is open to serious challenge. Notice that if the
second premise is wholly and literally true, then the conclusion must be false.
If, on the other hand, it is possible for something to move without being put
into motion by another, then why might there not be hundreds of "first
movers" instead of only one? Besides, it is by no means obvious that the
Aristotelean notions of a "first mover" or "first cause"
bear much resemblance to the god of Christianity. So even if the argument
succeeded it might be of little use in defence of orthodox religion.
Aquinas's fourth
way is a variety of Moral
Argument. It begins with the factual claim that we do make judgments about
the relative perfection of ordinary things. But the capacity to do so, Aquinas
argued, presupposes an absolute standard of perfection to which we compare
everything else. This argument relies more heavily on Platonic and Augustinian
notions, and has the advantage of defending the existence of god as moral
exemplar rather than as abstract intitiator of reality.
The fifth way is the
Teleological Argument:
the order and arrangement of the natural world (not merely its existence)
bespeaks the deliberate design of an intelligent creator. Although it is an
argument by analogy which can at best offer only probable reason for believing
the truth of its conclusion, this proof offers a concept of god that most fully
corresponds to the traditional elements of medieval Christian theology. Since
its empirical basis lies in our understanding of the operation of nature, this
line of reasoning tends to become more compelling the more thorough our
scientific knowledge is advanced.
Since the nature of
god can be known only analogically by reference to the created world, Aquinas
believed it worthwhile to devote great attention to the operation of nature.
Here, of course, the basic approach is that of Aristotle, but the commentaries
of Ibn Rushd provide a reliable guide as well.
Although we cannot
rationally eliminate the possiblity that matter itself is co-eternal with god,
Aquinas held, that undifferentiated prime matter can be nothing but pure
potentiality in any case. It is only through god's bestowal of a substantial
essence upon some portion of prime matter that a real material thing comes into
existence. Thus, everything is, in some sense, a hylomorphic composite
of matter and form for Aquinas, and god is the creator of all.
But, of course,
human beings are a special case. As Aristotle had supposed, the human soul is
the formal, efficient, and final cause of the human body. But in this one
special instance, Aquinas held that god can add existence directly, without any
admixture of prime matter, thus making possible the immortality of disembodied
human souls.
Even in this life, Aquinas
argued, the intellect is a higher faculty than the will in virtue of its
greater degree of independence from the body. As the agent of knowledge, the
human intellect comprehends the essences of things directly, making use of
sensory information only as the starting-point for its fundamentally rational
determinations. Although not all of Aquinas's contemporaries recognized,
understood, or accepted this view of human knowledge, it provided ample room
for the development of empirical investigations of the material world within
the context of traditional Christian doctrine.
Efforts to
incorporate elements of Aristotelean metaphysics within the general scheme of
Christian thought continued to stir controversy for a long time. Although Aquinas
himself showed great caution in applying the ideas of Ibn Rushd to Christian
theology, others were far more daring. Boetius of Dacia, for
example, raised serious questions about individual immortality, and Siger of Brabant
explicitly declared that human thought occurs only within the context of a
comprehensive, single, unified intellect—a notion that would re-emerge during
the modern period in the philosophy of Spinoza).
Philosophical dispute about
such matters has theological implications, and the church was not reluctant to
express its concern. In 1270 Etienne Tempier, the Bishop of Paris (encouraged
by Henry of Ghent) issued a formal condemnation of thirteen doctrines held by
"radical Aristoteleans," including the unity of intellect, causal
necessity, and the eternity of the world. In 1277 he expanded the number of
condemned doctrines to 219, this time including on the list some clearly Thomistic
teachings on the nature and individuation of substances and the role of reason
in knowledge of god. This encouraged the (mostly) neoplatonic Franciscans of
the late thirteenth century to pursue their attacks on the Dominican order's
more enthusiastic reliance upon the offensive use of Aristotle. Giles of Rome,
with a notable efforts to synthesize the chief doctrines of Aquinas with the
neoplatonic tradition, was a rare exception.
In the next
generation, John Duns
Scotus criticized many of the notions at the heart of the Thomistic
philosophy, placing more emphasis on the traditional Augustinian theology in
his own subtle and idiosyncratic exposition of a critical metaphysics. Since
the natural object of human intellect is Being itself, as comprehended under
the universal Forms, sensory information is often a misleading distraction from
reality. Thus, the truest knowledge of god and self is to be derived by
revelation and reason rather than from experience.
Since he conceived
of god as the truest Being, which universally encompasses all of the
perfections, Scotus followed Anselm in relying
upon the Ontological
Argument for god's existence. Sensory information, excluded from this
proof, cannot corrupt or distort its theological and even devotional
significance, which extablishes the perfect reality and freedom of the divine.
Still, Scotus granted that from a common-sense, rational standpoint the more empirical
Aristotelean arguments used by Aquinas have the virtue of greater clarity and
certainty.
Scotus earned a
reputation for great subtlety in reasoning, ironic mention of which by Tyndale
introduced the English word "dunce." Much of this reputation derives
from his frequent use of a sophisticated doctrine regarding three different kinds
of distinction that may be drawn among things:
·
Everyone granted that a real distinction is
drawn between genuinely separable things, each of which is capable of existing
independently of all others.
·
A merely mental (or conceptual)
distinction, on the other hand, is drawn wholly within our imaginations,
between aspects or descriptions that in fact apply to a single thing.
·
Between these extremes, Scotus now added the formal
distinction, a genuine, objective difference that holds between things that are
inseparable from each other in reality.
Thus, for example, god's
attributes of omnipotence, omniscience, benevolence, and freedom are only
formally distinct from each other, as are the concrete particular
instantiations of universal Forms.
This distinction among
distinctions has significant implications for the description of human nature.
Scotus conceded to Aquinas the now-standard hylomorphic view of
the soul as the form of the human body. But the functions of the soul are
formally distinct for Scotus, so that the will can be radically free in its
choices, even though the intellect is constrained by the structure of reason
and evidence. The immortality of the individual human soul, though not natural
in any sense, is guaranteed by the benevolent intervention of god.
An even more
strikingly modern conception of philosophy appeared in the work of William of Ockham, an
English Franciscan who represented his Order in major controversies over papal
authority and the vow of poverty. Concerned with the possibility that an
over-emphasis on universal forms might undermine the theological doctrine of
free will, Ockham secured his voluntaristic convictions by mounting a
full-scale attack on essentialism.
Thus, Ockham's
metaphysics is thoroughly nominalistic:
everything that exists is particular, and relations among these individuals are
purely conceptual. Thus, if we see a red shirt and a red car, there is no third
thing (the form or essence of Redness) that they share. Between this red button
and that red button there is only our own mental act of noticing their
resemblance with respect to color. Only concrete individual substances and
their particular features are real for Ockham; all else is manufactured by the
human mind.
This treatment of
the problem of universals is the most notable application of the famous
principle of parsimony that came to be known as Ockham's Razor. Ockham
declared that "plurality is not to be posited without necessity." By
this standard, the ontological
analysis of any situation should make reference to existing entities only when
the features at issue cannot be explained in any other way. Although opinions
may differ about whether or not the postulation of a new kind of beings is
genuinely necessary in certain circumstances, general acceptance of the Razor
places the burden of proof firmly on the side of those who would defend a more
complex view of the world.
Theologically,
Ockham agreed with Scotus that god is universal and has all of the infinite
attributes. But he emphasized even more strongly that god's freedom is
absolutely unlimited. According to Ockham's conception of voluntarism, god can
will anything at all, even an outright logical contradiction, even though we
cannot conceive of the possibility in specific terms. Thus, the regularity of
nature is guaranteed only by divine benevolence, not by any logical or causal
necessity.
Genuine human knowledge is
always intuitive and incorrigible
for Ockham, but its scope and extent are severely restricted by the limitations
of our finite understandings. Were we to depend solely upon such perfect
awareness of the external world, skepticism would be our only recourse. In the
practical conduct of life, however, Ockham supposed that mere belief, based on
sensory information and therefore prone to error, is nevertheless adequate for
our usual needs. This notion of the importance but limitations of empirical
knowledge would become a significant feature of British philosophy for many
centuries.
During the fourteenth and fifteenth
centuries, the critical spirit fostered by Scotus and Ockham began to
undermine confidence in the scholastic project of
synthesizing the philosophical and religious traditions in a comprehensive
system of thought. John of Mirecourt, for example, used the problem of devising
an adequate account of causation to argue that knowledge of the natural world
is severly limited, and Jean
Buridan abandoned theological pretension in order to focus narrowly on
logical analysis of arguments.
Nicholas of
Autrecourt argued that efforts to apply philosophical reasoning to Christian
doctrine had failed and should be abandoned. Hasdai Crescas among
the Jews and Meister Eckhart among the Christians employed rational methods
only in order to generate paradoxical results that would demonstrate the need
ro rely upon mystical union with god as the foundation for genuine human
knowledge.
The most remarkable of
these late scholastic figures was Nicolas of Cusa, who
made one final attempt at drawing together all of the inconsistent strands of
medieval philosophy by deliberately embracing contradiction. Just as god's
perfect unity can encompass otherwise contradictory attributes, Cusa argued, so
the contradictions apparent in the philosophical tradition should simply be
embraced in a single comprehensive whole, without any undue concern for its
logical consistency.
Medieval philosophy
had culminated in the cumulative achievements of scholasticism, a
grand system of thought developed by generations of patient scholars employing neoplatonic and Aristotelean
philosophy in the service of traditional Christian theology. But by the end of
the fifteenth century, confidence in the success of this enterprise had eroded,
and many thinkers tried to make a fresh start by rejecting such extensive
reliance on the authority of earlier scholars. Just as religious reformers
challenged ecclesiastical authority and made individual believers responsible
for their own relation to god, prominent Renaissance thinkers
proposed an analogous elimination of all appeals to authority in education and
science.
Educational practice
was revolutionized by the recovery of ancient documents, the rejection of
institutional authority, and renewed emphasis on individual freedom. The humanists expressed an
enormous confidence in the power of reason as a source of profound
understanding of human nature and of our place in the natural order. Giovanni Pico della
Mirandola's Oration, for example, held forth the possibilities for a
comprehensive new order of knowledge relying on human understanding without
reference to divine revelation. For some, like Desiderius Erasmus and
Marsillio Ficino,
this spirit found expression in a return to careful study of classical texts in
their own right, without relying on centuries of scholastic commentary. But for
more revolutionary thinkers as diverse as Giordano Bruno and Francisco Suárez,
humanism offered an opportunity to incorporate modern developments along with
classical elements in entirely new systems of metaphysical
knowledge.
The rise of the new
science also offered a significant change in the prospects for human knowledge
of the natural world. Copernicus
argued on theoretical grounds for a heliocentric view of the universe, for
which Kepler
provided a more secure mathematical interpretation. Galileo contributed not
only an impressive series of direct observations of both celestial and
terrestrial motion but also a serious effort to explain and defend the new
methods. By abandoning explanation in terms of final causes, by emphasizing the
importance of observation, and by trying to develop quantified accounts of all,
renaissance scientists began to develop the foundations of a thoroughly
empirical view of the world.
This emerging emphasis on
empirical methods permanently transformed study of the natural world. Making
extensive use of sensory observations made possible by the development of new
instrumentation fostered an urge to seek quantification of every phenomenon.
There were exceptions like Herbert of Cherbury,
who hoped that the natural light of common notions imprinted innately in every
human being would provide perfect certainty as a foundation for Christianity.
But most of the moderns gladly embraced the methods, style, and content of the
new science.
While the
Renaissance encouraged abandonment of the benefits of scholastic learning, it
could offer only the promise that new ways of thinking might one day suitably
replace them. Along with high hopes for the achievement of human knowledge came
significant doubts about its possibility. By recovering and translating the
work of Sextus
Empiricus, humanist scholars introduced the tradition of classical skepticism as an
element of modern thought. Turning the power of reasoning against itself at
every opportunity, the Pyrrhonists
proposed that we suspend all belief whenever we find ourselves capable of
doubting the truth of what we suppose. The trouble is that very little beyond
immediate personal experience can pass this test of indubitability.
The greatest exponent of
modern Pyrrhonism was Michel
de Montaigne, whose Essays (1580, 1588) gave prominent place to skeptical
arguments. Any attempt to achieve knowledge is misguided, on his view, because
it arrogantly supposes that the natural world and everything in it exists only
for the satisfaction of our idle curiosity. Since the evidence of our senses
is notoriously liable to error and the reliability of logical reasoning cannot
be demonstrated without circularity, we would indeed be better off to doubt
everything and rest comfortably with mere opinion. Even the new science offers
no hope, Montaigne argued, since it must eventually be surpassed in the same
way that it has overcome the old. These concerns created a challenge to which
modern philosophers were bound to respond.
Against the
background of humanistic scholarship, the rise of the new science, and the
challenge of skepticism, modern philosophers were preoccupied with
philosophical issues in several distinct areas:
·
Epistemology: Can human
beings achieve any certain knowledge of the world? If so, what are the sources
upon which genuine knowledge depends? In particular, how does sense perception
operate in service of human knowledge?
·
Metaphysics: What
kinds of things ultimately compose the universe? In particular, what are the
distinctive features of human nature, and how do they function in relation to
each other and the world at large? Does god exist?
·
Ethics: By what
standards should human conduct be evaluated? Which actions are morally right,
and what motivates us to perform them? Is moral life possible without the
support of religious belief?
·
Metaphilosophy: Does
philosophy have a distinctive place in human life generally? What are the
proper aims and methods of philosophical inquiry?
Although not every philosopher addressed all of these
issues and some philosophers had much more to say about some issues than
others, our survey of modern philosophy will trace the content of their
responses to questions of these basic sorts.
British politician
and entrepeneur Francis
Bacon, for example, expressed the modern spirit well in a series of works
designed to replace stultified Aristoteleanism with improved methods for
achieving truth. Assuming that the difficulties we experience are invariably
the results of poor training and can therefore be eliminated, Bacon promised
that the adoption of more appropriate habits of thinking will enable individual
thinkers to transcend them.
Believing that the
first step toward knowledge is to identify its major obstacles, Bacon took note
of four distinct varieties of distractions that too often prevent us from
understanding the world correctly:
·
Idols of the Tribe, which
arise from human nature generally, encourage us to over-estimate our own
importance within the greater scheme of things by supposing that everything
must truly be as it appears to us.
·
Idols of the Cave, which
arise from our individual natures, lead each one of us to extrapolate
inappropriately from his or her own case to a hasty generalization about
humanity, life, or nature generally.
·
Idols of the Marketplace, which
arise from the use of language as a means of communication, interfere with an
unbiased perception of natural phenomena by forcing us to express everything in
traditional terms.
·
Idols of the Theatre, which
arise from academic philosophy itself, produces an inclination to build and
defend elaborate systems of thought that are founded on little evidence from
ordinary experience.
Once we notice the
effects that these "Idols" have upon us, Bacon supposed, we are in a
position to avoid them, and our knowledge of nature will accordingly improve.
In a more positive spirit,
Bacon proposed a patient method borrowed from the practice of the new
scientists of the preceding generation. First, we must use our senses (properly
freed from the idols) to collect and organize many particular instances from
experience. Resisting the urge to generalize whenever it is possible to do so,
we adhere firmly to an experimental appreciation of the natural world. Only
when it seems unavoidable will we then tentatively postulate modest rules about
the coordination and reqularity we observe among these cases, subject always to
confirmation or refutation by future experiences.
Even more than
Bacon, Thomas Hobbes illustrated the transition from medieval to
modern thinking in Britain. His Leviathan effectively developed a vocabulary for
philosophy in the English language by using Anglicized versions of the
technical terms employed by Greek and Latin authors. Careful use of words to
signify common ideas in the mind, Hobbes maintained, avoids the difficulties to
which human reasoning is most obviously prone and makes it possible to
articulate a clear conception of reality. (Leviathan I 4)
For Hobbes, that conception
is bound to be a mechanistic
one: the movements of physical objects will turn out to be sufficient to
explain everything in the universe. The chief purpose of scientific
investigation, then, is to develop a geometrical account of the motion of
bodies, which will reveal the genuine basis of their causal interactions and
the regularity of the natural world. Thus, Hobbes defended a strictly materialist view of the
world.
Human beings are
physical objects, according to Hobbes, sophisticated machines all of whose
functions and activities can be described and explained in purely mechanistic
terms. Even thought itself, therefore, must be understood as an instance of the
physical operation of the human body. Sensation, for example, involves a series
of mechanical processes operating within the human nervous system, by means of
which the sensible features of material things produce ideas in the brains of
the human beings who perceive them. (Leviathan I 1)
Human action is
similarly to be explained on Hobbes's view. Specific desires and appetites
arise in the human body and are experienced as discomforts or pains which must
be overcome. Thus, each of us is motivated to act in such ways as we believe
likely to relieve our discomfort, to preserve and promote our own well-being. (Leviathan I 6) Everything we choose to do is strictly
determined by this natural inclination to relieve the physical pressures that
impinge upon our bodies. Human volition is nothing but
the determination of the will by the strongest present desire.
Hobbes nevertheless
supposed that human agents are free in the sense that
their activities are not under constraint from anyone else. On this compatibilist view, we
have no reason to complain about the strict determination of the will so long
as we are not subject to interference from outside ourselves. (Leviathan II 21)
As Hobbes
acknowledged, this account of human nature emphasizes our animal nature,
leaving each of us to live independently of everyone else, acting only in his
or her own self-interest, without regard for others. This produces what he
called the "state of war," a way of life that is certain to prove
"solitary, poor, nasty, brutish, and short." (Leviathan I 13) The only escape is by entering into
contracts with each other—mutually beneficial agreements to surrender our
individual interests in order to achieve the advantages of security that only a
social existence can provide. (Leviathan I 14)
Unable to rely
indefinitely on their individual powers in the effort to secure livelihood and
contentment, Hobbes supposed, human beings join together in the formation of a
commonwealth. Thus, the commonwealth as a whole embodies a network of
associated contracts and provides for the highest form of social organization.
On Hobbes's view, the formation of the commonwealth creates a new, artificial
person (the Leviathan) to whom all responsibility for social order and public
welfare is entrusted. (Leviathan II 17)
Of course, someone
must make decisions on behalf of this new whole, and that person will be the
sovereign. The commonwealth-creating covenant is not in essence a relationship
between subjects and their sovereign at all. Rather, what counts is the
relationship among subjects, all of whom agree to divest themselves of their
native powers in order to secure the benefits of orderly government by obeying
the dictates of the sovereign authority. (Leviathan II 18) That's why the minority who might prefer
a different sovereign authority have no complaint, on Hobbes's view: even
though they have no respect for this particular sovereign, they are still bound
by their contract with fellow-subjects to be governed by a single authority.
The sovereign is nothing more than the institutional embodiment of orderly
government.
Since the decisions
of the sovereign are entirely arbitrary, it hardly matters where they come
from, so long as they are understood and obeyed universally. Thus, Hobbes's
account explicitly leaves open the possibility that the sovereign will itself
be a corporate person—a legislature or an assembly of all citizens—as well as a
single human being. Regarding these three forms, however, Hobbes himself
maintained that the commonwealth operates most effectively when a hereditary
monarch assumes the sovereign role. (Leviathan II 19) Investing power in a single natural
person who can choose advisors and rule consistently without fear of internal
conflicts is the best fulfillment of our social needs. Thus, the radical
metaphysical positions defended by Hobbes lead to a notably conservative
political result, an endorsement of the paternalistic view.
Hobbes argued that
the commonwealth secures the liberty of its citizens. Genuine human freedom, he
maintained, is just the ability to carry out one's will without interference
from others. This doesn't entail an absence of law; indeed, our agreement to be
subject to a common authority helps each of us to secure liberty with respect
to others. (Leviathan II 21) Submission to the sovereign is
absolutely decisive, except where it is silent or where it claims control over
individual rights to life itself, which cannot be transferred to anyone else.
But the structure provided by orderly government, according to Hobbes, enhances
rather than restricts individual liberty.
Whether or not the
sovereign is a single heredetary monarch, of course, its administration of
social order may require the cooperation and assistance of others. Within the
commonwealth as a whole, there may arise smaller "bodies politic"
with authority over portions of the lives of those who enter into them. The
sovereign will appoint agents whose responsibility is to act on its behalf in
matters of less than highest importance. Most important, the will of the
sovereign for its subjects will be expressed in the form of civil laws that
have either been decreed or tacitly accepted. (Leviathan II 26) Criminal violations of these laws by any
subject will be appropriately punished by the sovereign authority.
Despite his firm insistence
on the vital role of the sovereign as the embodiment of the commonwealth,
Hobbes acknowledged that there are particular circumstances under which it may
fail to accomplish its purpose. (Leviathan II 29) If the sovereign has too little power, is
made subject to its own laws, or allows its power to be divided, problems will
arise. Similarly, if individual subjects make private judgments of right and
wrong based on conscience, succomb to religious enthisiasm, or acquire
excessive private property, the state will suffer. Even a well-designed
commonwealth may, over time, cease to function and will be dissolved.
The first great philosopher
of the modern era was René Descartes, whose new approach won him recognition as
the progenitor of modern philosophy. Descartes's pursuit of mathematical and
scientific truth soon led to a profound rejection of the scholastic tradition
in which he had been educated. Much of his work was concerned with the
provision of a secure foundation for the advancement of human knowledge through
the natural sciences. Fearing the condemnation of the church, however,
Descartes was rightly cautious about publicly expressing the full measure of
his radical views. The philosophical writings for which he is remembered are
therefore extremely circumspect in their treatment of controversial issues.
After years of work
in private, Descartes finally published a preliminary statement of his views in
the Discourse on the Method of Rightly Conducting the Reason
(1637). Since mathematics has genuinely achieved the certainty for which human
thinkers yearn, he argued, we rightly turn to mathematical reasoning as a model
for progress in human knowledge more generally. Expressing perfect confidence
in the capacity of human reason to achieve knowledge, Descartes proposed an
intellectual process no less unsettling than the architectural destruction and
rebuilding of an entire town. In order to be absolutely sure that we accept
only what is genuinely certain, we must first deliberately renounce all of the
firmly held but questionable beliefs we have previously acquired by experience
and education.
The progress and
certainty of mathematical knowledge, Descartes supposed, provide an emulable
model for a similarly productive philosophical method, characterized by four
simple rules:
1.
Accept as true only what is indubitable.
2.
Divide every question into manageable parts.
3.
Begin with the simplest issues and ascend to the
more complex.
4.
Review frequently enough to retain the whole
argument at once.
This quasi-mathematical
procedure for the achievement of knowledge is typical of a rationalistic
approach to epistemology.
While engaged in
such a comprehensive revision of our beliefs, Descartes supposed it prudent to
adhere to a modest, conventional way of life that provides a secure and
comfortable environment in which to pursue serious study. The stoic underpinnings of
this "provisional morality" are evident in the emphasis on changing
oneself to fit the world. Its general importance as an avenue to the
contemplative life, however, is more general. Great intellectual upheavals can
best be undertaken during relatively calm and stable periods of life.
In this context,
Descartes offered a brief description of his own experience with the proper
approach to knowledge. Begin by renouncing any belief that can be doubted,
including especially the testimony of the senses; then use the perfect
certainty of one's own existence, which survives this doubt, as the foundation
for a demonstration of the providential reliability of one's faculties
generally. Significant knowledge of the world, Descartes supposed, can be
achieved only by following this epistemological method, the rationalism of relying
on a mathematical model and eliminating the distraction of sensory information
in order to pursue the demonstrations of pure reason.
Later sections of
the Discourse (along with the supplementary scientific essays with which
it was published) trace some of the more significant consequences of following
the Cartesian method in philosophy. His mechanistic
inclinations emerge clearly in these sections, with frequent reminders of the
success of physical explanations of complex phenomena. Non-human animals, on
Descartes's view, are complex organic machines, all of whose actions can be
fully explained without any reference to the operation of mind in thinking.
In fact, Descartes
declared, most of human behavior, like that of animals, is susceptible to
simple mechanistic explanation. Cleverly designed automata could successfully
mimic nearly all of what we do. Thus, Descartes argued, it is only the general
ability to adapt to widely varying circumstances—and, in particular, the
capacity to respond creatively in the use of language—that provides a sure test
for the presence of an immaterial soul associated with the normal human body.
But Descartes supposed that
no matter how human-like an animal or machine could be made to appear in its
form or operations, it would always be possible to distinguish it from a real
human being by two functional criteria. Although an animal or machine may be
capable of performing any one activity as well as (or even better than) we can,
he argued, each human being is capable of a greater variety of different
activities than could be performed by anything lacking a soul. In a special
instance of this general point, Descartes held that although an animal or
machine might be made to utter sounds resembling human speech in response to
specific stimuli, only an immaterial thinking substance could engage in the
creative use of language required for responding appropriately to any
unexpected circumstances. My puppy is a loyal companion, and my computer is a
powerful instrument, but neither of them can engage in a decent conversation.
(This criterion anticipated the more formal requirements of the Turing test.)
For a more complete formal
presentation of this foundational experience, we must turn to the Meditationes
de prima Philosophia (Meditations
on First Philosophy) (1641), in which Descartes offered to contemporary
theologians his proofs of the existence of god and the immortality of the human
soul. This explicit concern for religious matters does not reflect any loss of
interest in pursuing the goals of science. By sharply distinguishing mind from
body, Descartes hoped to preserve a distinct arena for the church while
securing the freedom of scientists to develop mechanistic accounts
of physical phenomena. In this way, he supposed it possible to satisfy the
requirements of Christian doctrine, but discourage the interference of the
church in scientific matters and promote further observational exploration of
the material world.
The arrangement of the Meditations,
Descartes emphasized, is not the order of reasons; that is, it makes no effort
to proceed from the metaphysical
foundations of reality to the dependent existence of lesser beings, as Spinoza
would later try to do. Instead, this book follows the order of thoughts; that
is, it traces the epistemological
progress an individual thinker might follow in establishing knowledge at a
level of perfect certainty. Thus, these are truly Meditations: we are
meant to put ourselves in the place of the first-person narrator, experiencing
for ourselves the benefits of the philosophical method.
The basic strategy
of Descartes's method
of doubt is to defeat skepticism on its own
ground. Begin by doubting the truth of everything—not only the evidence of the senses
and the more extravagant cultural presuppositions, but even the fundamental
process of reasoning itself. If any particular truth about the world can
survive this extreme skeptical challenge, then it must be truly indubitable and
therefore a perfectly certain foundation for knowledge. The First Meditation,
then, is an extended exercise in learning to doubt everything that I believe,
considered at three distinct levels:
1.
Perceptual Illusion
First, Descartes noted that
the testimony of the senses with respect to any particular judgment about the
external world may turn out to be mistaken. (Med. I)
Things are not always just as they seem at first glance (or at first hearing,
etc.) to be. But then, Descartes argues, it is prudent never wholly to trust in
the truth of what we perceive. In ordinary life, of course, we adjust for
mistaken perceptions by reference to correct perceptions. But since we cannot
be sure at first which cases are veridical and which are not, it is possible
(if not always feasible) to doubt any particular bit of apparent sensory
knowledge.
2.
The Dream Problem
Second, Descartes
raised a more systematic method for doubting the legitimacy of all sensory
perception. Since my most vivid dreams are internally indistinguishible from
waking experience, he argued, it is possible that everything I now
"perceive" to be part of the physical world outside me is in fact
nothing more than a fanciful fabrication of my own imagination. On this
supposition, it is possible to doubt that any physical thing really exists,
that there is an external world at all. (Med. I)
Severe as it is, this level
of doubt is not utterly comprehensive, since the truths of mathematics and the
content of simple natures remain unaffected. Even if there is no material world
(and thus, even in my dreams) two plus three makes five and red looks red to
me. In order to doubt the veracity of such fundamental beliefs, I must extend
the method of doubting even more hyperbolically.
3.
A Deceiving God
Finally, then,
Descartes raises even more comprehensive doubts by inviting us to consider a
radical hypothesis derived from one of our most treasured traditional beliefs.
What if (as religion teaches) there is an omnipotent god, but that deity
devotes its full attention to deceiving me? (Med. I)
The problem here is not merely that I might be forced by god to believe what something
which is in fact false. Descartes means to raise the far more devastating
possibility that whenever I believe anything, even if it has always been true
up until now, a truly omnipotent deceiver could at that very moment choose to
change the world so as to render my belief false. On this supposition, it seems
possible to doubt the truth of absolutely anything I might come to believe.
Although the
hypothesis of a deceiving god best serves the logical structure of the Meditations
as a whole, Descartes offered two alternative versions of the hypothetical
doubt for the benefit of those who might take offense at even a counter-factual
suggestion of impiety. It may seem more palatable to the devout to consider the
possibility that I systematically deceive myself or that there is some evil
demon who perpetually tortures me with my own error. The point in each case is
that it is possible for every belief I entertain to be false.
Remember that the point of
the entire exercise is to out-do the skeptics at their own game, to raise the
broadest possible grounds for doubt, so that whatever we come to believe in the
face of such challenges will indeed be that which cannot be doubted. It is
worthwhile to pause here, wallowing in the depths of Cartesian doubt at the end
of the First Meditation, the better to appreciate the escape he offers at the
outset of Meditation Two.
The Second
Meditation begins with a review of the First. Remember that I am committed to
suspending judgment with respect to anything about which I can conceive any
doubt, and my doubts are extensive. I mistrust every report of my senses, I
regard the material world as nothing more than a dream, and I suppose that an
omnipotent god renders false each proposition that I am even inclined to
believe. Since everything therefore seems to be dubitable, does it follow that
I can be certain of nothing at all?
It does not.
Descartes claimed that one thing emerges as true even under the strict
conditions imposed by the otherwise universal doubt: "I am, I exist"
is necessarily true whenever the thought occurs to me. (Med.
II) This truth neither derives from sensory information nor depends upon
the reality of an external world, and I would have to exist even if I were
systematically deceived. For even an omnipotent god could not cause it to be
true, at one and the same time, both that I am deceived and that
I do not exist. If I am deceived, then at least I am.
Although Descartes's
reasoning here is best known in the Latin translation of its expression in the Discourse,
"cogito, ergo
sum" ("I think, therefore I am"), it is not merely an
inference from the activity of thinking to the existence of an agent which
performs that activity. It is intended rather as an intuition of one's own
reality, an expression of the indubitability of first-person experience, the
logical self-certification of self-conscious awareness in any form.
Skepticism is thereby
defeated, according to Descartes. No matter how many skeptical challenges are
raised—indeed, even if things are much worse than the most extravagant skeptic
ever claimed—there is at least one fragment of genuine human knowledge: my perfect
certainty of my own existence. From this starting-point, Descartes supposed, it
is possible to achieve indubitable knowledge of many other propositions as
well.
An initial
consequence may be drawn directly from the intuitive certainty of the cogito
itself. If I know that I am, Descartes argued, I must also know what I am; an
understanding of my true nature must be contained implicitly in the content of
my awareness.
What then, is this
"I" that doubts, that may be deceived, that thinks? Since I became
certain of my existence while entertaining serious doubts about sensory information
and the existence of a material world, none of the apparent features of my
human body can have been crucial for my understanding of myself. But all that
is left is my thought itself, so Descartes concluded that "sum res
cogitans" ("I am a thing that thinks"). (Med.
II) In Descartes's terms, I am a substance whose
inseparable attribute (or entire essence) is thought,
with all its modes: doubting, willing, conceiving, believing, etc. What I
really am is a mind
[Lat. mens]
or soul [Lat. anima]. So
completely am I identified with my conscious awareness, Descartes claimed, that
if I were to stop thinking altogether, it would follow that I no longer existed
at all. At this point, nothing else about human nature can be determined with
such perfect certainty.
In ordinary life, my experience
of bodies may appear to be more vivid than self-consciousness, but Descartes
argued that sensory appearances actually provide no reliable knowledge of the
external world. If I hold a piece of beeswax while approaching the fire, all of
the qualities it
presents to my senses change dramatically while the wax itself remains. (Med.
II) It follows that the impressions of sense are unreliable guides even to
the nature of bodies. (Notice here that the identity of the piece of
wax depends solely upon its spatial location; that's a significant hint about
Descartes's view of the true nature of material things, which we'll see in more
detail in Meditation
Five.)
At the outset of the
Third Meditation, Descartes tried to use this first truth as the paradigm for his
general account of the possibilities for achieving human knowledge. In the cogito,
awareness of myself, of thinking, and of existence are somehow
combined in such a way as to result in an intuitive grasp of a truth that
cannot be doubted. Perhaps we can find in other cases the same grounds for indubitable truth.
But what is it?
The answer lies in
Descartes's theory of ideas.
Considered formally, as the content of my thinking activity, the ideas involved
in the cogito are unusually clear and distinct. (Med.
III) But ideas may also be considered objectively, as the mental
representatives of things that really exist. According to a representative realist
like Descartes, then, the connections among our ideas yield truth only when
they correspond to
the way the world really is. But it is not obvious that our clear and distinct
ideas do correspond to the reality of things, since we suppose that there may
be an omnipotent deceiver.
In some measure, the
reliability of our ideas may depend on the source from which they are derived.
Descartes held that there are only three possibilities: all of our ideas are
either adventitious (entering the mind from the outside world) or factitious
(manufactured by the mind itself) or innate
(inscribed on the mind by god). (Med.
III) But I don't yet know that there is an outside world, and I can imagine
almost anything, so everything depends on whether god exists and deceives me.
The next step in the
pursuit of knowledge, then, is to prove that god does indeed exist.
Descartes's starting point for such a proof is the principle that the cause of
any idea must have at least as much reality as the content of the idea itself.
But since my idea of god has an absolutely unlimited content, the cause of this
idea must itself be infinite, and only the truly existing god is that. In other
words, my idea of god cannot be either adventitious or factitious (since I
could neither experience god directly nor discover the concept of perfection in
myself), so it must be innately provided by god. Therefore, god exists. (Med.
III)
As a backup to this
argument, Descartes offered a traditional version of the cosmological argument
for god's existence. From the cogito I know that I exist, and since I am
not perfect in every way, I cannot have caused myself. So something else must
have caused my existence, and no matter what that something is (my parents?),
we could ask what caused it to exist. The chain of causes must end eventually,
and that will be with the ultimate, perfect, self-caused being, or god.
As Antoine Arnauld
pointed out in an Objection published along with the Meditations
themselves, there is a problem with this reasoning. Since Descartes will use
the existence (and veracity) of god to prove the reliability of clear and
distinct ideas in Meditation Four, his use of clear and distinct ideas to prove
the existence of god in Meditation Three is an example of circular reasoning.
Descartes replied that his argument is not circular because intuitive
reasoning—in the proof of god as in the cogito—requires no further
support in the moment of its conception. We must rely on a non-deceiving god
only as the guarantor of veridical memory, when a
demonstrative argument involves too many steps to be held in the mind at once.
But this response is not entirely convincing.
The problem is a
significant one, since the proof of god's existence is not only the first
attempt to establish the reality of something outside the self but also the
foundation for every further attempt to do so. If this proof fails, then
Descartes's hopes for human knowledge are severely curtailed, and I am stuck in
solipsism, unable
to be perfectly certain of anything more than my own existence as a thinking
thing. With this reservation in mind, we'll continue through the Meditations,
seeing how Descartes tried to dismantle his own reasons for doubt.
The proof of god's
existence actually makes the hypothetical doubt of
the First Meditation a little worse: I now know that there really is a being
powerful enough to deceive me at every turn. But Descartes argued that since
all perfections naturally go together, and since deception is invariably the
product of imperfection, it follows that the truly omnipotent being has no
reason or motive for deception. God does not deceive, and doubt of the deepest
sort may be abandoned forever. (Med.
IV) It follows that the simple natures and the truths of mathematics are
now secure. In fact, Descartes maintained, I can now live in perfect confidence
that my intellectual faculties, bestowed on me by a veracious god, are properly
designed for the apprehension of truth.
But this seems to
imply too much: if I have a divinely-endowed capacity for discovering the
truth, then why don't I always achieve it? The problem is not that I lack
knowledge of some things; that only means that I am limited. Rather, the
question is why I so often make mistakes, believing what is false despite my
possession of god-given mental abilities. Descartes's answer derives from an
analysis of the nature of human cognition generally.
Every mental act of
judgment, Descartes held, is the product of two distinct faculties: the understanding, which
merely observes or perceives, and the will, which assents to
the belief in question. Considered separately, the understanding (although
limited in scope) is adequate for human needs, since it comprehends completely
everything for which it has clear and distinct ideas. Similarly, the will as an
independent faculty is perfect, since it (like the will of god) is perfectly
free in every respect. Thus, god has benevolently provided me with two
faculties, neither of which is designed to produce error instead of true
belief. Yet I do make mistakes, by misusing my free will to assent on occasions
for which my understanding does not have clear and distinct ideas. (Med.
IV) For Descartes, error is virtually a moral failing, the willful exercise
of my powers of believing in excess of my ability to perceive the truth.
Since the truths of
reason have been restored by the demonstration of god's veracity, Descartes
employed mathematical reasoning to discover the essence of bodies in the Fifth
Meditation. We do not yet know whether there are any material objects,
because the dream
problem remains in force, but Descartes supposed that we can determine what
they would be like if there were any by relying upon reason alone, since
mathematics achieves certainty without supposing the reality of its objects.
According to
Descartes, the essence of material substance is simply extension, the property
of filling up space. (Med. V)
So solid geometry, which describes the possibility of dividing an otherwise
uniform space into distinct parts, is a complete guide to the essence of body.
It follows that there can be in reality only one extended substance, comprising
all matter in a
single spatial whole. From this, Descartes concluded that individual bodies are
merely modes of the one extended being, that there can be no space void of
extension, and that all motion must proceed by circular vortex. Thus, again,
the true nature of bodies is understood by pure thought, without any information
from the senses.
By the way, this
explanation of essences suggested to Descartes another proof of god's
existence, a modern variation on the Ontological Argument.
Just as the essence of a triangle includes its having interior angles that add
up to a straight line, Descartes argued, so the essence of god, understood as a
being in whom all perfections are united, includes necessary existence in
reality. (Med. V) As Descartes himself noted, this argument is no more
certain than the truths of mathematics, so it also rests on the reliability of
clear and distinct ideas, secured in turn by the proofs of god's existence and
veracity in the Third and Fourth Meditations.
In the Sixth
Meditation, Descartes finally tried to eliminate the dream problem by
proving that there is a material world and that bodies do really exist. His
argument derives from the supposition that divinely-bestowed human faculties of
cognition must always be regarded as adequately designed for some specific
purpose. Since three of our faculties involve representation of physical
things, the argument proceeds in three distinct stages. (Med.
VI)
First, since the
understanding conceives of extended things through its comprehension of
geometrical form, it must at least be possible for things of this sort to
exist. Second, since the imagination is directed exclusively toward the ideas
of bodies and of the ways in which they might be purposefully altered, it is
probable that there really are such things. Finally, since the faculty of sense
perception is an entirely passive ability to receive ideas of physical objects
produced in me by some external source outside my control, it is certain that
such objects must truly exist.
The only alternative
explanation for perception, Descartes noted, is that god directly puts the
ideas of bodies into my mind without there acutally being anything real that
corresponds to them. (This is precisely the possibility that Malebranche would later
accept as the correct account of the material world.) But Descartes supposed
that a non-deceiving god would never maliciously give me so complete a set of
ideas without also causing their natural objects to exist in fact. Hence, the
bodies I perceive do really exist.
Among the physical
objects I perceive are the organic bodies of animals, other human beings, and
myself. So it is finally appropriate to consider human nature as a whole: how
am I, considered as a thinking thing, concerned with the organism I see in the
mirror? What is the true relation between the mind and the body of any human
being? According to Descartes, the two are utterly distinct.
The Sixth Meditation
contains two arguments in defence of Cartesian dualism: First, since
the mind and the body can each be conceived clearly and distinctly apart from
each other, it follows that god could cause either to exist independently of
the other, and this satisfies the traditional criteria for a metaphysical real
distinction. (Med. VI) Second, the essence of body as a geometrically defined
region of space includes the possibility of its infinite divisibility, but the
mind, despite the variety of its many faculties and operations, must be
conceived as a single, unitary, indivisible being; since incompatible
properties cannot inhere in any one substance, the mind and body are perfectly
distinct. (Med. VI)
This radical
separation of mind and body makes it difficult to account for the apparent interaction
of the two in my own case. In ordinary experience, it surely seems that the
volitions of my mind can cause physical movements in my body and that the
physical states of my body can produce effects on my mental operations. But on
Descartes's view, there can be no substantial connection between the two, nor
did he believe it appropriate to think of the mind as residing in the body as a
pilot resides within a ship. Although he offered several tenatative suggestions
in his correspondence with Princess Elizabeth,
Descartes largely left for future generations the task of developing some
reasonable account of volition and sensation, either by securing the
possibility of mind-body interaction
or by proposing some alternative explanation of the appearances.
On the other hand,
Cartesian dualism offers some clear advantages: For one thing, it provides an
easy proof of the natural immortality of the human mind or soul, which cannot
be substantially affected by death, understood as an alteration of the states
of the physical organism. In addition, the distinction of mind from body
establishes the absolute independence of the material realm from the spiritual,
securing the freedom of scientists to rely exclusively on observation for their
development of mechanistic
explanations of physical events.
Descartes worked out
his own detailed theories about the physical operation of the material world in
Le Monde (The World), but uncertainty about ecclesiastical
reactions prevented him from publishing it. The final sections of the Discourse,
however, include several significant hints about the positions he was prepared
to defend. Their explanations of the activities of living organisms make the mechanistic
implications of the Cartesian view more evident.
Since, as everyone
acknowledges, non-human animals do not have souls, Descartes concluded that animals must be merely
complex machines. Since they lack any immaterial thinking substance, animals
cannot think, and all of the movements of their bodies can, in principle, be
explained in purely mechanical terms. (Descartes himself incorrectly supposed
that the nervous system functions as a complex hydraulic machine.) But since
the structure of the human body and the behavior of human beings are similar to
the structure and behavior of some animals, it is obvious that many human
actions can also be given a mechanistic explanation. La Mettrie later
followed this line of reasoning to its ultimate conclusion, supposing human
beings to be nothing more than Cartesian machines.
The philosophy of
Descartes won ready acceptance in the second half of the
seventeenth century, expecially in France and Holland. Although few of his
followers, known collectively as Cartesians, employed
his methods, they showed great diligence and ingenuity in their efforts to
explain, defend, and advance his central doctrines.
In the physical
sciences, for example, Cavendish,
Rohault, and Régis were happy to
abandon all efforts to employ final causes in
their pursuit of mechanistic accounts of physical phenomena and animal
behavior. On this basis, however, such philosophers were able to progress
beyond a simple affirmation of the mysterious reality of mind-body interaction.
Metaphysicians like Cordemoy and Geulincx fared little
better in their efforts to deal with this crucial problem with dualism. If
there is no genuine causal interaction between independent substances, we seem
driven to suppose that the actions of mind and body are merely parallel or
divinely synchronized.
Not everyone was entirely
satisfied by the epistemological foundations of the Cartesian scheme, either.
Critics like Arnauld,
Nicole, and Foucher drew attention
to the inherent difficulty of explaining in representationalist
terms how our ideas of things can be known to resemble the things themselves
and the implausibility of reliance upon innate ideas. Conway went even
further, rejecting the dualistic foundations of Descartes's substance-ontology
along with his approach to human knowledge.
One
seventeenth-century thinker of greater independent significance was Blaise Pascal, with
his unusual blend of religious piety, scientific curiosity, and mathematical
genius. Led by his deep religious feelings to participate fully in the
pietistic Jansenism
of the Port-Royal community,
Pascal maintained that formal reasoning about god can never provide an adequate
substitute for genuine personal concern for the faith: "The heart has its
reasons that reason cannot know."
Pascal's mathematical
acumen was no less remarkable than that of Descartes; his work anticipated the
development of game theory and the modern methods of calculating probability. In fact,
his famous "Wager" applies these mathematical techniques to the
prudence of religious conviction in the absence of adequate evidence: since the
consequences of believing are infinitely beneficial if there is a god and only
slightly inconvenient if there is not, while the outcome of atheism is only
somewhat more pleasant if there is no god and eternally costly if there is, the
expected value of
theism is much greater than that of atheism, and it is reasonable to stake
one's life on the possibility that god does exist.
The most original
and influential philosopher of the Cartesian tradition was Nicolas Malebranche.
Noting the steady progress of efforts to provide mechanistic accounts of the
behavior of the human body, Malebranche concluded that the mind and body are
not only substantially distinct but causally independent of each other. The
appearance of genuine interaction arises from what is in fact merely the
perfect parallelism of events in the mental and physical realms.
According to
Malebranche, then, our ideas of bodies do not result from any causal influence
that physical objects have on our senses; rather, they are produced in our
minds directly by god. Thus, he supposed, in sense perception what literally
happens is that we "see all things in god." Similarly, our wills have
no causal influence on the material world, but god provides for the
coordination of our volitions with the movement of bodies. In general, since
there is no causal interaction, it is the power of god alone that secures a
perpetual, happy coincidence of the states and operations of minds and bodies.
Since only god's activity
is efficacious in either mental or physical things, apparent causes in either
realm are merely the occasions for the appearance of their supposed effects in
the other. Thus, the views of Malebranche are often referred to collectively as
occasionalism.
Although the entire theory found few enthusiastic adherents, Malebranche's
analysis of the regularities exhibited in nature by causally independent beings
and events was greatly influential on later philosophers, including Berkeley
and Hume.
Descartes
regarded mathematical reasoning as the paradigm for progress in human
knowledge, but Baruch Spinoza took this rationalistic appreciation
even further, developing and expressing his mature philosophical views "in
the geometrical manner." Thus, in the posthumously-published Ethica
Ordine Geometrico Demonstrata (Ethics)
(1677), Spinoza claimed to deduce the entire system of thought from a
restricted set of definitions and self-evident axioms.
Drawing specific doctrines
from Cartesian thought, medieval scholasticism,
and the Jewish
tradition, Spinoza blended everything together into a comprehensive vision
of the universe as a coherent whole governed solely by the immutable laws of
logical necessity. Rigorous thought reveals that there can be only a single
substance, of which we (and everything else) are merely insignificant parts.
Although we may find it difficult to take any comfort in Spinoza's account of
our place in the world, we are bound to admire the logical consistency with
which he works out all the details.
The definitions and
axioms with which Book I of the Ethics begins are critical to Spinoza's
enterprise, since they are intended to carry his central doctrines as deductive
consequences. Although they generally follow the usages of the scholastic tradition,
many of them also include special features of great significance to the thought
of Spinoza.
Substance, for example,
he defined not only as existing in itself but also as "conceived through
itself." (I Def. iii) This places a severe limit on the possibility of
interaction between things, since Spinoza delared that causation is a relation
of logical necessity, such that knowledge of the effect requires knowledge of
its cause. (I Ax. iii-iv) Few will disagree that god is a substance with
infinite attributes, but this definition carries some surprising implications
in Spinoza's view of the world; notice also that freedom, according to Spinoza,
just means that a thing exists and acts by its own nature rather than by
external compulsion. (I Def. vi-vii)
The numbered propositions
that follow make it clear what Spinoza is getting at. Since causal interaction
is impossible between two substances that differ essentially, and no two substances
can share a common attribute or essence, it follows
that no substance can produce genuine change in any another substance. Each
must be the cause of its own existence and, since it cannot be subject to
limitations imposed from outside itself, must also be absolutely infinite.
Things that appear to be finite individuals interacting with each other, then,
cannot themselves be substances; in reality, they can be nothing more than the
modifications of a self-caused, infinite substance. (I Prop. v-viii) And that, of course, is god.
Spinoza supposed it
easy to demonstrate that such a being does really exist. As the ontological argument
makes clear, god's very essence includes existence. Moreover, nothing else
could possible prevent the existence of that substance which has infinite
attributes in itself. Finally, although it depends on a posteriori
grounds to which Spinoza would rather not appeal, the cosmological argument
helps us to understand that since we ourselves exist, so must an infinite cause
of the universe. Thus, god exists. (I Prop. xi)
What is more, god is
a being with infinitely many attributes, each of which is itself infinite, upon
which no limits of any kind can be imposed. So Spinoza argued that infinite
substance must be indivisible, eternal, and unitary. There can be only one such
substance, "god or nature," in which everything else is wholly
contained. Thus, Spinoza is an extreme monist, for whom
"Whatever is, is in god." Every mind and every body, every thought
and every movement, all are nothing more than aspects of the one true being.
Thus, god is an extended as well as a thinking substance.
Finally, god is perfectly free on Spinoza's definition.
Of course it would be incorrect to suppose that god has any choices about what
to do. Everything that happens is not only causally determined but actually
flows by logical necessity from immutable laws. But since everything is merely
a part of god, those laws themselves, and cause and effect alike, are simply
aspects of the divine essence, which is wholly self-contained and therefore
free. (I Prop. xvii) Because there is no other substance, god's actions
can never be influenced by anything else.
God is the only
genuine cause. From the essence of god, Spinoza held, infinitely many things
flow in infinitely many different ways. The entire universe emanates inexorably
from the immutable core of infinite substance. Though we often find it natural
to think of the world from the outside looking in, as natura naturata
(nature natured), its internal structure can be more accurately conceived from
the inside looking out, as natura naturans (nature naturing). (I Prop. xxix) Since all that happens radiates from the common
core, everything hangs together as part of the coherent whole which just is god
or nature in itself.
The infinite substance and
each of its infinitely many distinct attributes (among which only thought and
extension are familiar to us) are eternal expressions of the immutable essence of
god. From each attribute flow the infinite immediate modes (infinite intellect
and motion or rest), and out of these in turn come the infinite mediate modes
(truth and the face of the universe). Thus, every mode of substance (each
individual mind or body) is determined to be as it is because of the divine
essence. Even the finite modes (particular thoughts and actions) are inevitably
and wholly determined by the nature of god. Hence, everything in the world is
as it must be; nothing could be other than it is. (I Prop. xxxiii)
In the same
deductive geometrical form, Book II of the Ethics offers an extensive
account of human beings: our existence, our nature, and our activities.
Remember that we are aware of only two of the infinitely many attributes of
god, extension and thought, and that each of them independently expresses the
entire essence of the one infinite substance.
That is, in the
natural world (god's body), the attribute of extension, modified by varying
degrees of motion and rest, produces the face of the universe, which includes
all of the particular physical events which are the modes of extension. (This
is almost exactly like Descartes's
account of the material world.) Similarly, in the mental realm (god's
idea), the attribute of thought—modified by infinite intellect—produces the
truth, which includes all of the particular mental events which are the modes
of thought. Since they arise from distinct attributes, each of these realms is
causally independent of the other and wholly self-contained: the natural world
and the mental realm are separate closed systems.
Despite the
impossibility of any causal interaction between the two, Spinoza supposed that
the inevitable unfolding of each these two independent attributes must proceed
in perfect parallel with that of the other. "The order and connection of
ideas is the same as the order and connection of things." (II Prop. vii) (And so, of course, must be the order and
connection of each of the infinitely many other attributes of god.) Since the
development of each aspect of the divine nature follows with logical necessity
from its own fundamental attribute, and since all of the attributes, in turn,
derive from the central essential being of one and the same infinite substance,
each exhibits the same characteristic pattern of organization even though they
have no influence on each other.
Thus, for every object of
the natural world that exists as a mode of the attribute of extension, there is
a corresponding idea in the mind of god that exists as a mode of the attribute
of thought. For every physical event that takes place in the material realm as
the result of exclusively physical causes, a corresponding mental event must
occur in the infinite intellect as a result of purely mental causes. Since
everything flows from the same infinite being, we may suppose that the
structure of thought in infinite intellect comprises an accurate representation
of the structure of every other attribute.
Consider what all of
this implies for each of us as a living human being. We are not substances,
according to Spinoza, for only god or Nature is truly substantial; we can exist
only as modes, depending for our existence upon the reality of the one real
being. Since the one infinite substance is the cause of everything, each of us
can only be regarded as a tiny cross-section of the whole.
Of course, that
cross-section does include elements from each of the infinitely many attributes
of that substance. In particular, we know that in each case it involves both a
human body, the movements of whose organic parts are all physical events that
flow from god via the attribute of extension, and a human mind, the formation
of whose ideas are all mental events that flow from god via the attribute of
thought. Although there can be no causal interaction between the mind and the
body, the order and connection of their internal elements are perfectly
correlated.
Thus, in principle, the
human mind contains ideas that perfectly represent the parts of the human body.
But since many of these ideas are inadequate in the sense that they do not
carry with them internal signs of their accuracy, we do not necessarily know
our own bodies. (II Prop. xxviii) If, for example, there must be in my mind an
idea that corresponds to each particular organic state of my spleen; but since
I am unaware of its bodily correlate, it provides me with no clear awareness of
that representational object.
Spinoza maintained
that human beings do have particular faculties whose functions are to provide
some degree of knowledge. I typically assume, for example, that there may be
some correlation between thought and extension with regard to sensations
produced by the action of other bodies upon my eyes, ears, and fingertips. Even
my memory may occasionally harbor some evidence of the order and connection
common to things and ideas. And in self-conscious awareness, I seem to achieve
genuine knowledge of myself by representing my mind to itself, using ideas to
signify other ideas.
Near the end of Book
II, then, Spinoza distinguished three kinds of knowledge of which we may be
capable: First, opinion,
derived either from vague sensory experience or from the signification of words
in the memory or imagination, provides only inadequate ideas and cannot be
relied upon as a source of truth. Second, reason, which
begins with simple adequate ideas and by analyzing causal or logical necessity
proceeds toward awareness of their more general causes, does provide us with
truth. But intuition,
in which the mind deduces the structure of reality from the very essence or
idea of god, is the great source of adequate ideas, the highest form of
knowledge, and the ultimate guarantor of truth. (II Prop. xl)
Spinoza therefore
recommends a three-step process for the achievement of human knowledge: First,
disregard the misleading testimony of the senses and conventional learning.
Second, starting from the adequate idea of any one existing thing, reason back
to the eternal attribute of god from which it derives. Finally, use this
knowledge of the divine essence to intuit everything else that ever was, is, and
will be. Indeed, he supposed that the Ethics itself is an exercise in
this ultimate pursuit of indubitable
knowledge.
The last three Books
of the Ethics collectively describe how to live consistently on
Spinozistic principles. All human behavior results from desire or the
perception of pain, so (like events of any sort) it flows necessarily from the
eternal attributes of thought and extension. But Spinoza pointed out a crucial
distinction between two kinds of cases: Sometimes I am wholly unaware of the
causes that underlie what I do and am simply overwhelmed by the strength of my
momentary passions. But at other times I have adequate knowledge of the motives
for what I do and can engage in deliberate action because I recognize my place
within the grander scheme of reality as a whole.
It is in this
fashion that moral value enters Spinoza's system. Good (or evil) just is what
serves (or hinders) the long-term interests of life. Since my actions
invariably follow from emotion or desire, I always do what I believe to be the
good, which will truly be so if I have adequate ideas of everything involved.
The greatest good of human life, then, is to understand one's place in the
structure of the universe as a natural expression of the essence of god.
But how can we speak of
moral responsibility when every human action is determined with rigid
necessity? Remember that, for Spinoza, freedom is
self-determination, so when I acquire adequate knowledge of the emotions and
desires that are the internal causes of all my actions, when I understand why I
do what I do, then I am truly free. Although I can neither change the way
things are nor hope that I will be rewarded, I must continue to live and act
with the calm confidence that I am a necessary component of an infinitely
greater and more important whole. This way of life may not be easy, Spinoza
declared, "But all noble things are as difficult as they are rare."
The last of the
great Continental
Rationalists was Gottfried Wilhelm Leibniz. Known in his own time as a
legal advisor to the Court of Hanover and as a practicing mathematician who
co-invented the calculus, Leibniz applied the rigorous standards of formal reasoning in an
effort to comprehend everything. A suitably sophisticated logical scheme, he
believed, can serve as a reliable guide to the ultimate structure of reality.
But Leibniz published
little of his philosophical work during his own lifetime. For an understanding
of the technical logical foundations of his system, we must rely upon letters
and notebooks which became available only centuries later and upon the
aphoristic summary of its results in La Monadologie
(Monadology)
(1714). His Discours de Metaphysique (Discourse on
Metaphysics) (1686) and Théodicée
(Theodicy) (1710) present to the general public more popular
expositions of Leibniz's central themes. Our strategy will be to begin with the
logical theories and work outward to the more accessible doctrines.
The basis for
Leibniz's philosophy is pure logical analysis. Every
proposition, he believed, can be expressed in subject-predicate form. What is
more, every true proposition is a statement of identity whose predicate is
wholly contained in its subject, like "2 + 3 = 5." In this sense, all
propositions are analytic
for Leibniz. But since the required analysis may be difficult, he distinguished
two kinds of true propositions: (Monadology 33)
Truths of Reason are explicit statements of identity, or reducible to
explicit identities by a substitution of the definitions of their terms. Since
a finite analysis always reveals the identity-structure of such truths, they
cannot be denied without contradiction and are perfectly necessary.
Truths of Fact, on the other hand, are implicit statements of identity,
the grounds for whose truth may not be evident to us. These truths are merely contingent and may be
subject to dispute, since only an infinite analysis could show them to be
identities.
Anything that human beings
can believe or know, Leibniz held, must be expressed in one or the other of
these two basic forms. The central insight of Leibniz's system is that all existential propositions
are truths of fact, not truths of reason. This simple doctrine has many
significant consequences.
Consider next how
this logic of propositions applies to the structure of reality itself. The
subject of any proposition signifies a complete individual substance, a simple,
indivisible, dimensionless being or monad, while the
predicate signifies some quality,
property, or power. Thus, each true proposition represents the fact that some
feature is actually contained in this substance.
Each monad is a complete
individual substance in the sense that it contains all of its features—past,
present, and future. Because statements of identity are timeless, the facts
they express perpetually obtain. (Thus, for example, I am the person whose
daughter was born in 1982 and the person who now develops this web site and the
person who will vacation in Manitoba next summer; since each of these
predicates can be truly affirmed of me, each of these features is contained in
me.) Everything that was, is, or will ever be true of any substance is already
contained in it. (Monadology 22)
Moreover, each monad
is a complete individual substance in the sense that its being is
utterly independent of everything else. Because statements of identity are
self-contained, any apparent relation between substances must actually be a
matching pair of features that each possesses alone. (Thus, for example, I
happen to have the property of being Aaron's father, and Aaron happens to have
the property of being my son, but these are two facts, not one.) Hence, on
Leibniz's view, there can be no interaction between substances, each of which
is purely active. Monads are "windowless." (Monadology 7)
Where Spinoza saw the world
as a single comprehensive substance like Descartes's extended matter, then,
Leibniz supposed that the world is composed of many discrete particles, each of
which is simple, active, and independent of every other, like Descartes's minds
or souls. The rationalists' common reliance upon mathematical models of
reasoning led to startlingly different conceptions of the universe. Yet the
rationality, consistency, and necessity within each system is clear.
Another way of
summing up the structure of the universe on Leibniz's view is by reviewing the
great logical principles from which all truths are said to flow:
The Principle of
Contradiction generates the truths of reason, each of which states the
connection between an individual substance and one of its finite number of
essential features. (Monadology 31) It would be a contradiction to deny any of
these propositions, since the substance would not be what it is unless it had
all of these features. Truths of reason, then, are not influenced by any
contingent fact about the world; they are true "in all possible
worlds." Thus, for example, "Garth Kemerling is a human being"
would be necessarily true even if my parents had been childless.
The Principle of
Sufficient Reason generates the truths of fact, each of which states the
connection between an existing individual substance and one of its infinitely
many accidental features or relations. (Monadology 32) The sufficient reason for the truth of
each of these propositions is that this substance does exist as a member of the
consistent set of monads which constitutes the actual world. Truths of fact,
then, depend upon the reciprocal mirroring of each existing substance by every
other. Thus, for example, "Garth Kemerling is an oldest child" is
contingently true only because my parents had no children before I was born.
The Principle of the
Identity of Indiscernibles establishes the fact that, within the set of monads
that constitutes any possible world, no two can be exactly alike. (Monadology 9) If, on the contrary, there were two
distinct but perfectly identical
substances, Leibniz argued, then there could be no sufficient reason for each
to occupy its own location rather than that of the other. More positively,
since each monad mirrors the entire structure of the world, each must reflect a
unique set of relations to every other.
Finally, the Principle of
the Plenum (or principle
of plenitude) affirms that the actual world, considered as a set of monads,
is as full as it can possibly be. Since there is no genuine interaction among
distinct substances, there would be no sufficient reason for the non-existence
of any monad that would be consistent with the others within a possible world.
Hence, anything that can happen will; every possibility within this world must
be actualized. The world in which we live, then, is but one among the
infinitely many possible worlds that might have existed. What makes this one
special?
Since we experience
the actual world as full of physical objects, Leibniz provided a detailed
account of the nature of bodies. As Descartes had correctly noted, the essence
of matter is that
it is spatially extended. But since every extended thing, no matter how small,
is in principle divisible into even smaller parts, it is apparent that all
material objects are compound beings made up of simple elements. But from this
Leibniz concluded that the ultimate constitutents of the world must be simple,
indivisible, and therefore unextended, particles—dimensionless mathematical
points. So the entire world of extended matter is in reality constructed from
simple immaterial substances, monads, or entelechies.
In fact, Leibniz
held that neither space nor time is a fundamental feature of reality. Of course
individual substances stand in spatial relation to each other, but relations of
this sort are reducible in logic to the non-relational features of windowless
monads. In exactly the same way, temporal relations can be logically analyzed
as the timeless properties of individual monads. Space and time are unreal, but
references to spatial location and temporal duration provide a convenient
short-hand for keeping track of the relations among the consistent set of
monads which is the actual world.
What is at work here again
is Leibniz's notion of complete individual substances, each of which mirrors
every other. A monad not only contains all of its own past, present, and future
features but also, by virtue of a complex web of spatio-temporal references,
some representation of every other monad, each of which in turn
contains . . . . In a universe of windowless mirrors, each
reflects any other, along with its reflections of every other, and so on ad
infinitum. It is for this reason that an infinite analysis would be
required to reveal the otherwise implicit identity at the heart of every truth
of fact. In order fully to understand the simple fact that my eyes are brown,
one would have to consider the eye-color of all of my ancestors, the anatomical
structure of the iris, my personal opthalmological history, the
culturally-defined concept of color, the poetical associations of dark eyes,
etc., etc., etc.; the slightest difference in any one of these things would
undermine the truth of this matter of fact. Existential assertions presuppose the
reality of just this one among all possible worlds as the actual world.
Both in the Monadology
and at the more popular level of presentation that characterizes the Discourse
on Metaphysics, Leibniz (like Descartes) resolved some of the most thorny
philosophical problems by reference to god. God (alone) exists necessarily, and
everything else flows from the divine nature. Limited only by contradiction,
god first conceives of every possible world—the world with just one monad; the
worlds with exactly two monads; those with three, with seventeen, with five
billion, etc. Then god simply chooses which of them to create.
Of course even god
must have a sufficient reason for actualizing this world rather than any other.
The most direct advantage of this world is that (as the plenum principle
requires) it is the fullest. That is, more things exist and/or more events
actually take place in this world than in any other consistent set of
interrelated monads. In a more lofty tone, Leibniz declared that a benevolent
god would choose to create whatever possible world contained the smallest
amount of evil;
hence (in a phrase that would later be mocked by Voltaire) this is
"the best of all
possible worlds," according to Leibniz. Nothing about it could be
changed without making things worse rather than better on the whole.
Similarly, the
existence of a benevolent god can be used to account for the smooth operation
of a universe that consists of indefinitely many distinct individual
substances, none of which have any causal influence over any other. (Monadology 51) A crucial element of god's creative
activity, Leibniz held, is the establishment of a "pre-established
harmony" among all existing things. Like well-made clocks that have been
synchronized, wound, and set in motion together, the monads that make up our
world are independent, self-contained, purely active beings whose features
coincide without any genuine interaction among them.
One special case of this
pre-established harmony, of course, accounts for the apparent interaction of
mind and body in a human being as nothing more than the perfect parallelism of thier
functions. In fact, the human mind is just the dominant member of a local
cluster of monads which collectively constitute the associated human body. (Monadology 63) Neither has any real effect on the other,
but these monads are most clearly reflected in each others' foreground. Thus,
in both sensation
and volition, the
divinely-ordained coincidence of bodily movements and mental thoughts creates
an illusion of genuine causal influence.
The possibility
human knowledge emerges more clearly from a slightly more technical account of
Leibniz's position. All monads have the capacity for perception of the external
world in the sense that, as complete individual substances, each of them
contains as properties unconscious images of its spatio-temporal relations to
everything else. (Monadology 19) These innate ideas constitute the unique
point of view from which any monad may be said to represent the world as a
whole.
But Leibniz held
that some monads—namely, the souls of animals and human beings—also have
conscious apperception
in the sense that they are capable of employing sensory ideas as
representations of physical things outside themselves. And a very few
monads—namely, spirits such as ourselves and god—possess the even greater
capacity of self-consciousness,
of which genuine knowledge is the finest example. Although Leibniz himself did
not draw the inference directly, notice that if a cluster of dimensionless
monads can make up an extended body, it might be equally possible for a cluster
of unconscious monads to constitute a thinking thing.
What Leibniz did claim is
that we have the free
will required for moral responsibility even though all of our future
actions are already contained in us (along with the future of the entire actual
world). Any awareness of those contingent future actions would follow from the
principle of sufficient reason only upon an infinite analysis of my nature.
Hence, since I lack knowledge of what I will do tomorrow, it will seem to me as
if I act freely when I do it. Like space and time, freedom is a benevolent
illusion that adequately provides for life in an uncertain world.
Descartes, Spinoza, and
Leibniz illustrate well the range of diverse outcomes that may result from an
effort to understand the world through a priori
knowledge. If their systems of thought seem implausibly remote from the world
of ordinary experience, it may help to remember that modern science leads to a
similar result. Once we grant that the reality of things may be quite different
from the way they appear to us, only the internal coherence of the scheme of
thought makes much difference. Next we'll look at modern philosophers who were
more determined to make sense out of the materials provided in everyday life.
We now leave the Continent for an extended look
at philosophy in Great Britain during the seventeenth and
eighteenth centuries. Here the favored model for achieving human knowledge
was not the abstract mathematical reasoning so admired by the rationalists but the
more concrete observations of natural science. Heeding the call of Francis Bacon, British
scientists had pursued a vigorous program of observation and experiment with
great success. Isaac
Newton showed that both celestial and terrestial motion could be explained
by reference to a simple set of laws of motion and gravitation; Robert Boyle
investigated the behavior of gasses and proposed a general theory of matter as a collection
of corpuscles; and Thomas Sydenham began to use observational methods for the
diagnosis and treatment of disease.
Philosopher
John Locke greatly admired the achievements that these
scientists (his friends in the Royal Society) had made in physics, chemistry,
and medicine, and he sought to clear the ground for future developments by
providing a theory of
knowledge compatible with such carefully-conducted study of nature.
The goal of Locke's An Essay Concerning Human Understanding (1690), then, is
to establish epistemological foundations for the new science by examining the
reliability, scope, and limitations of human knowledge in contrast with with
the pretensions of uncritical belief, borrowed opinion, and mere superstition.
Since the sciences had already demonstrated their practical success, Locke
tried to apply their Baconian methods to the pursuit of his own philosophical
aims. In order to discover how the human understanding achieves knowledge, we must
trace that knowledge to its origins in our experience.
Locke's
investigation into human knowledge began by asking how we acquire the basic
materials out of which that knowledge is composed, our ideas. For
Locke, an idea is whatever is directly before the mind in an act of thinking. (Essay I i 8) (Note that this is an extremely broad
definition: it includes concrete sensory images, abstract intellectual
concepts, and everything in between. The colors and shapes I see before me
right now are ideas, and so are my hunger, my memories of the ocean, my hopes
for my children, the multiplication tables, and the principles of democratic
government.) Ideas, then, are the immediate objects of all thought, the meaning
or signification of all words, and the mental representatives of all things.
Locke's question was, where do we get all of these ideas which are the content
of our knowedge?
First, Locke eliminated one bad answer to the
question. Most of Book I of the Essay is devoted to a detailed
refutation of the belief that any of our knowledge is innate. Against the
claims of the Cambridge
Platonists and Herbert
of Cherbury, Locke insisted that neither the speculative principles of
logic and metaphysics nor the practical principles of morality are inscribed on
our minds from birth. Such propositions do not in fact have the universal
consent of all human beings, Locke argued, since children and the mentally
defective do not assent to them. Moreover, even if everyone did accept these
principles, their universality could be better explained in terms of
self-evidence or shared experience than by reference to a presumed innate
origin. (Essay I ii 3-5) Innatism is the refuge of lazy
intellectual dictators who wish thereby to impose their provincial notions upon
others. Besides, Locke held, our knowledge cannot be innate because none of the
ideas of which it is composed are innate.
As the correct answer to the question, Locke
proposed the fundamental principle of empiricism: all of our
knowledge and ideas arise from experience. (Essay II i 2) The initially empty room of the mind is
furnished with ideas of two sorts: first, by sensation we obtain ideas
of things we suppose to exist outside us in the physical world; second, by reflection
we come to have ideas of our own mental operations. Thus, for example,
"hard," "red," "loud," "cold,"
"sweet," and "aromatic" are all ideas of sensation, while
"perceiving," "remembering," "abstracting," and
"thinking" are all ideas of reflection. ("Pleasure,"
"unity," and "existence," Locke held, are ideas that come
to us from both sensation and reflection.) Everything we know, everything we
believe, every thought we can entertain is made up of ideas of sensation and
reflection and nothing else.
But
wait. It isn't true that I can think only about what I myself have experienced;
I can certainly think about dinosaurs (or unicorns) even though I have never
seen one for myself. So Locke's claim must be about the ultimate origin of our
ideas, the source of their content. He distinguished between simple and complex
ideas and acknowledged that we often employ our mental capacities in order
manufacture complex ideas by conjoining simpler components. My idea of
"unicorn," for example, may be compounded from the ideas of
"horse" and "single spiral horn," and these ideas in turn
are compounded from less complex elements. What Locke held was that every
complex idea can be analyzed into component parts and that the final elements
of any complete analysis must be simple ideas, each of which is derived
directly from experience. Even so, the empiricist program is an ambitious one,
and Locke devoted Book II of the Essay to a lengthy effort to show that
every idea could, in principle, be derived from experience.
Locke began his survey of our mental contents
with the simple ideas of sensation, including those of colors, sounds, tastes,
smells, shapes, size, and solidity. With just a little thought about specific
examples of such ideas, we notice a significant difference among them: the
color of the wall in front of me seems to vary widely from time to time,
depending on the light in the room and the condition of my eyes, while its
solidity persists independently of such factors. Following the lead of Galileo and Boyle, Locke explained
this difference in corpuscularian
fashion, by reference to the different ways in which the qualities of things
produce our ideas of them.
The primary qualities of an object are
its intrinsic
features, those it really has, including the "Bulk, Figure, Texture, and
Motion" of its parts. (Essay II viii 9) Since these features are inseparable
from the thing even when it is divided into parts too small for us to perceive,
the primary qualities are independent of our perception of them. When we do
perceive the primary qualities of larger objects, Locke believed, our ideas
exactly resemble the qualities as they are in things.
The secondary qualities of an object, on
the other hand, are nothing in the thing itself but the power to produce in us
the ideas of "Colors, Sounds, Smells, Tastes, etc." (Essay II viii 10) In these cases, our ideas do not
resemble their causes, which are in fact nothing other than the primary
qualities of the insensible parts of things. The powers, or tertiary
qualities, of an object are just its capacities to cause perceptible changes in
other things.
Thus, for example, the primary qualities of this
rose include all of its quantifiable features, its mass and momentum, its
chemical composition and microscopic structure; these are the features of the
thing itself. The secondary qualities of the rose, on the other hand, include
the ideas it produces in me, its yellow color, its delicate fragrance; these
are the merely the effects of the primary qualities of its corpuscles on my
eyes and nose. Like the pain I feel when I stick my finger on a thorn, the
color and smell are not features of the rose itself.
Some
distinction of this sort is important for any representative realist.
Many instances of perceptual
illusion can be explained by reference to the way secondary qualities
depend upon our sensory organs, but the possibility of accurate information
about the primary qualities is preserved, at least in principle. The botanical
expert may be able to achieve detailed knowledge of the nature of roses, but
that knowledge is not necessary for my appreciation of their beauty.
Even if the simple ideas of sensation provide us
with ample material for thinking, what we make of them is largely up to us. In
his survey of ideas of reflection, Locke listed a variety of mental operations
that we perform upon our ideas.
Notice that in each of these sections (Essay
II ix-xii), Locke defined the relevant mental operations as we experience them
in ourselves, but then went on to consider carefully the extent to which other animals seem capable
of performing the same activities. This procedure has different results from Descartes's doctrinal
rejection of animal thinking: according to Locke, only abstraction (the
operation most crucial in forming the ideas of mixed modes, on which morality
depends) is utterly beyond the capacity of any animal. (Essay II xi 10)
Perception of ideas through the senses and
retention of ideas in memory, Locke held, are passive powers of the mind,
beyond our direct voluntary control and heavily dependent on the material
conditions of the human body. The active powers of the mind include
distinguishing, comparing, compounding, and abstracting. It is by employing
these powers, Locke supposed, that we manufacture new, complex ideas from the
simple elements provided by experience. The resulting complex ideas are of
three sorts: (Essay II xii 4-7)
Modes are complex ideas
that combine simpler elements to form a new whole that is assumed to be
incapable of existing except as a part or feature of something else. The ideas
of "three," "seventy-five," and even "infinity,"
for example, are all modes derived from the simple idea of "unity."
We can understand these ideas and know their mathematical functions, whether or
not there actually exist numbers of things to which they would apply in
reality. "Mixed modes" similarly combine simple components without
any presumption about their conformity to existing patterns, yielding all of
our complex ideas of human actions and their value.
Substances are the complex
ideas of real particular things that are supposed to exist on their own and to
account for the unity and persistence of the features they exhibit. The ideas
of "my only son," "the largest planet in the solar system,"
and "tulips," for example, are compounded from simpler ideas of
sensation and reflection. Each is the idea of a thing (or kind of thing) that
could really exist on its own. Since we don't understand all of the inner
workings of natural objects, Locke supposed, our complex ideas of substances
usually rely heavily on their secondary qualities and powers—the effects they
are observed to have on ourselves and other things.
Relations are complex ideas of
the ways in which other ideas may be connected with each other, in fact or in
thought. The ideas of "younger," "stronger," and
"cause and effect," for example, all involve some reference to the
comparison of two or more other ideas.
Locke
obviously could not analyze the content of every particular idea that any
individual has ever had. But his defence of the empiricist principle did
require him to show in principle that any complex idea can be derived from the
simple ideas of sensation and reflection. The clarity, reality, adequacy, and
truth of all of our ideas, Locke supposed, depend upon the success with which
they fulfill their representative function. Here, we'll consider one of the
most significant and difficult examples from each category:
Among our modal ideas, Locke believed that those
of mixed modes, which combine both sensory and reflective elements, are
especially important, since they include the ideas of human actions and provide
for their moral evaluation. Among the mixed modes, the ideas of power,
volition, and liberty are the most crucial and difficult. To them Locke devoted
a chapter (II xxi) that grew, with alterations in later editions, to become the
longest in the Essay.
The idea of power is illustrated every time we
do something. Whether we think or move, the feeling that our mental preference
leads to action provides a simple instance of power. The exercise of that power
is volition or will, and the action taken as a result is a voluntary one.
Liberty or freedom,
on Locke's view, is the power to act on our volition, whatever it may be,
without any external compulsion or restraint. (Essay II xxi 7-12)
Under
these definitions, the question of whether we have free will does not arise for
Locke, since it involves what would later come to be called a category mistake. In
particular, it does not matter whether we have control over our own
preferences, whether we are free to will whatever we wish. (Essay II xxi 23-25) In fact, Locke offered a strictly hedonistic account of
human motivation, according to which our preferences are invariably determined
by the desire to seek pleasure and avoid pain. (Essay II vii 3) What does matter for freedom and moral
responsibility is that we can act on our preferences, whatever their source,
without any outside interference. If I could have done otherwise (given a
different preference), then I act freely and am responsible for my action.
The idea of a
particular substance
is the complex idea of a set of coexisting qualities and powers, together with
the supposition that there is some unknown substrate upon which they all
depend. Locke is derisive about the confused idea of this something, "we
know not what," that is supposed by scholastic philosophers. (Essay II xxiii 2) But he cannot eliminate the concept of
substance altogether, since he, too, must account for the existence and
coherence of just this group of features.
About species or
kinds of substances, Locke offers a more sophisticated explanation. Our complex
idea of a specific kind of substance—"gold" or "horse," for
example—is the collection of features by reference to which we classify
individual substances as belonging to that kind. (Essay II xxiii 6-8) These nominal essences,
developed for our convenience in sorting things into kinds, rely heavily upon
the secondary qualities and powers that are the most obvious features of such
things in our experience—the color, weight, and malleability of gold, for
example, and the shape, noises, and movements of horses.
As a corpuscularian, Locke
supposed that individual substances must also have real essences, the
primary qualities of their insensible parts, which cause all of their
qualities. But since we cannot observe the "real inner constitutions"
of things, we cannot use them for purposes of classification, nor can we even
understand their causal influence on our perception. (Essay III vi 6) Since Locke doubted that real essences
could ever be discovered, he was thrown back on the supposition of an
underlying reality which we cannot know.
This account imposes a
severe limitation on the possibilities of our knowledge of substances.
According to Locke, the mechanical operations of nature remain hidden to us.
Careful observation and experimentation may support a reliable set of
generalizations about the appearances of the kinds of things we commonly
encounter, but we cannot even conceive of their true natures.
Among our ideas of relations,
the strongest is that of identity.
Locke held that the criteria for identity depend upon the kind of thing we are
considering. Substantial identity requires the unique spatio-temporal history
that is just the existence of each substance, but this is not the only
consideration in all cases.
The identity of the
tree outside my window, for example, does not depend on the substantial
identity of its parts (in fact, they change from day to day and season to
season); what matters in this case is the organization of those parts into a
common life. A similar explanation, Locke held, accounts for the identity of
animals and human beings. (Essay II xxvii 4-6) We recognize living bodies at
different times by the organization of their material parts rather than by
their substantial composition.
In analogous
fashion, Locke explained personal identity independently of identity of
substance. The idea of the person is that of a
moral agent who can be held responsible for his or her actions. (Essay II xxvii 9) But Locke used a series of hypothetical
examples to show that the identity of an underlying immaterial substance or
soul is neither necessary
nor sufficient for personal identity in this sense. Even the identity of
the same human body (though we may rely upon that for third-person attributions
of identity) is not truly relevant. The only thing that does matter, on Locke's
view, is that the person self-consciously appropriates actions as its own.
This is, as Locke says, a
"forensic" notion of personal identity; its aim is to secure the
justice and effectiveness of moral sanctions. (Essay II xxvii 26) If, and only if, I now remember having
committed a particular act in the past can I be justly punished for having done
so. If, and only if, I project myself into the future can the prospect of
punishment or reward influence my deliberations about how to act now. Locke's
way of thinking about personal identity has shaped discussions of the issue
ever since.
Locke devoted Book
III of the Essay to a discussion of language. His basic notion is clear:
words signify ideas. Thus, the meaning of a word is always the idea it
signifies in the minds of those who use it. (Essay III ii 2) Of course, those ideas are presumed in
turn to represent things, but the accuracy of that representation does not
directly affect the meaning of the word. The names of substances, for example,
signify the complex ideas Locke called their nominal essences, not the real nature
of the substances themselves. Thus, common names for substances are sortal
terms by means of which we classify things as we observe them to be; we can
agree upon the meaning of such terms even though we remain ignorant of the real
essences of the things themselves.
The chief point of Locke's
theory of language was to eliminate the verbal disputes that arise when words
are used without clear signification. It is always reasonable to ask for the
meaning of a word, that is, to know what idea it signifies. If a speaker cannot
supply the idea behind the word, then it has no meaning. Many of the academic
squabbles that obstruct advancement in human knowledge, Locke believed, could
be dissolved by careful attention to the meaning of words.
Having provided a
thorough account of the origins of our ideas in experience, Locke opens Book IV
of the Essay with a deceptively simple definition of knowledge. Knowledge
is just perception of the agreement or disagreement of our ideas. (Essay IV i 2) We know the truth of a proposition when we
become aware of the relation between the ideas it conjoins. This can occur in
three ways, each with its characteristic degree of certainty.
Intuitive knowledge involves direct and immediate recognition of the
agreement or disagreement of two ideas. (Essay IV ii 1) It yields perfect certainty, but is only
rarely available to us. I know intuitively that three is not the same as seven.
In demonstrative
knowledge we perceive the agreement or disagreement only indirectly, by
means of a series of intermediate ideas. (Essay IV ii 2) Since demonstration is a chain of
reasoning, its certainty is no greater than its weakest link; only if each step
is itself intuitively known will the demonstration as a whole be certain. If I
know that A is greater than B and that B is greater than C, then I know
demonstratively that A is greater than C.
Although intuition and
demonstration alone satisfy the definition of knowledge, Locke held that the
belief that our sensory ideas are caused by existing things deserves the name
of sensitive knowledge. (Essay IV ii 14) In the presence of a powerful, present
idea of sensation, we cannot doubt that it has some real cause outside us, even
though we do not know what that cause may be or how it produces the idea in us.
I have only sensitive knowledge that there is something producing the odor I
now smell.
Locke distinguished
four sorts of agreement or disagreement between ideas, perception of which
gives us four distinct types of knowledge: (Essay IV i 3-7)
Since knowledge of identity
and diversity requires only a direct comparison of the ideas involved, it
is intuitive whenever the ideas being compared are clear.
Knowledge of coexistence
would provide detailed information about features of the natural world that
occur together in our experience, but this scientific knowledge is restricted
by our ignorance of the real essences of substances; the best we can do is to
rely upon careful observations of the coincidental appearance of their
secondary qualities and powers.
Mathematics and
morality rest upon knowledge of relation, which Locke held to be
demonstrative whenever we form clear ideas and discover the links between them.
The degree of certainty in
our knowledge of real existence depends wholly upon the content of our
ideas in each case. Locke agreed with Descartes that we have intuitive knowledge of our
own existence, and he supposed it possible to achieve demonstrative
knowledge of god as the thinking creator of everything. But we have only
sensitive knowledge of the existence of other things presently before our
senses.
The result of all of
this is that our knowledge is severely limited in its extent. On Locke's
definition, we can achieve genuine knowledge only when we have clear ideas and
can trace the connection between them enough to perceive their agreement or
disagreement. (Essay IV iii 1-6) That doesn't happen very often,
especially where substances are at issue. The truths of mathematics are
demonstrable precisely because they are abstract: since my ideas of lines,
angles, and triangles are formed without any necessary reference to existing
things, I can prove that the interior angles of any triangle add up to a
straight line.
But any effort to
achieve genuine knowledge of the natural world must founder on our ignorance of
substances. We have "sensitive knowledge" of the existence of
something that causes our present sensory ideas. But we do not have adequate
ideas of the real essence of any substance, and even if we did, we would be
unable to discover any demonstrative link between that real essence and the
ideas it produces in us. The most careful observation can establish at best
only the secondary qualities and powers that appear to coexist in our
experience often enough to warrant our use of them as the nominal essence of a
kind of substance. (Essay IV xi 1-7)
Locke's efforts have
therefore led to a sobering conclusion. Certainty is rarely within our reach;
we must often be content with probable knowledge or mere opinion. Locke
ultimately recommends that we adopt significantly reduced epistemological
expectations.
Despite all of these
limitations, Locke believed that human knowledge is well-suited for the conduct
of human life. We have all the knowledge we need to secure our "great
concernments:" convenience in this life and the means for attaining a
better life hereafter. (Essay IV xii 11)
Survival and comfort
in daily life are attainable in spite of our ignorance of the hidden operations
of nature. We don't need to know the real essences of substances in order to
make use of them productively. (Indeed, Locke suggests, additional information
might actually make daily life more difficult.) Surely demonstrative knowledge
of the true nature of fire or food is unnecessary for my survival; my natural
aversion to the pain of being burned and desire for the pleasures of eating
provide ample practical guidance.
Doing the right
thing is also possible, since our action is properly guided by a demonstrable
morality. The truths of morality
are demonstrable for the same reason that the truths of mathematics are: the
mixed modes that describe possible human actions, of the moral rules that
govern them, and even of the possible agents that might perform them, are all
complex ideas manufactured by the mind without reference to the real existence
of substantial beings, so I can prove that murder is wrong.
Finally, we have all
the knowledge we need to enter into a proper relation to our creator. God's existence is
demonstrable, and the scriptures provide us with detailed information about the
divine will for our lives. (The precise boundary between reason and revelation,
Locke held, is itself known only as a matter of probable knowledge or opinion.)
In the end, then, Locke
believed that we have no reason to complain. Although restricted in extent, our
knowledge is sufficient for our needs. (Essay IV xiv 1-2) Respecting its limits will prevent us
from wasting effort on pointless wrangling. Since our experience is itself
limited, an empiricist epistemology can only advise caution and modesty in our
claims to know.
Locke's influence
extended through several
generations of British moral philosophers, who not only developed and
criticized his notion of a demonstrable morality but also worked within the
general framework of his empiricist epistemology.
Samuel Clarke followed
up on Locke's sketchy hints about the demonstrability of morals by proposing
extended proofs of the golden rule as a purely rational statement of the
natural distinction between good and evil.
In a series of
anonymous publications, Catherine
Cockburn supported this rationalistic account of moral obligation in
opposition to the emerging emphasis on self-interest moderated by external
sanctions as the sole sources of moral motivation.
John Toland
extrapolated from Locke's discussion of god to arrive at the notion of matural
religion as a legitimate product of human reason. Toland's Christianity not
Mysterious (1696) became a significant source for the later development of
English Deism.
Richard Cumberland and
Ralph Cudworth had
already attempted to show that morality can be grounded as a natural and
immutable system arising from our innate, universal feeling of benevolence
toward all human beings.
But this position
earned the scorn of Bernard
Mandeville, who regarded morality as the merely conventional rules of a
social group and supposed that all human action is inevitably guided only by
self-interest.
The third Earl of Shaftesbury opposed
ethical egoism by appealing to what he argued were the natural inclinations of
human agents to act rightly.
Francis Hutcheson
responded to these challenges by supplementing Locke's account of human
faculties. According to Hutcheson, we acquire the ideas of moral and aesthetic
value from an separate "moral sense," whose information guides us
appropriately toward virtuous action.
In the sermons of Joseph Butler, this
concept of a distinct capacity for perceiving good and evil became the more
theological notion of a divinely-provided
<../dy/c7.htm#consc">conscience that serves as the infallible guide
of human conduct.
The drift of this entire
tradition provided a background against which David Hume
was able to employ the notion of a moral sense to propose a purely naturalistic
account of human morality.
Locke's Dutch friend
Pierre Bayle stirred controversy by reviving interest in
Pyrrhonian skepticism
among French and British philosophers. His voluminous Dictionary
provided many opportunities for expostulation on contemporary philosophical
issues.
Bayle developed
serious questions about the success of modern philosophy. Cartesian
rationalism, he supposed, founders because the frailty of our faculties gives
us little reason for confidence in divine veracity. The fact that animals evidently do
think casts doubt upon the dualistic account of human nature, with its emphasis
on our immaterial souls.
Nor will empiricist
methods help. Locke's careful distinction between primary and secondary
qualities, Bayle argued, cannot be defended, since instances of perceptual illusion
arise with respect to both. When the critical arguments are fairly applied, we
will be seen to have no reliable information about qualities of either sort.
Thus, the use of representationalism
in defence of scientific knowledge inevitably drives us even further into
skepticism.
Religion and
morality may be secured even in the face of such skepticism, the Protestant
Bayle supposed, because they depend in no way on the achievements of reason.
Moral conduct, like all human behavior, results (in theist and atheist alike)
from the irrational influence of emotion, desire, and shame. True religion can
be based only on an entirely unreasoned faith.
Although direct influence
is difficult to prove, Bayle's skeptical arguments clearly anticipated the
direction in which empiricism would develop through the work of Berkeley and
Hume.
Irish philosopher George Berkeley
believed that Locke's Essay did not carry the principles of empiricism far enough.
While still an undergraduate, this future bishop of the Anglican church worked
out his trenchant criticism of Locke and proposed a simple but startling
alternative.
Philosophers like Descartes
and Locke tried to forestall problems of perceptual illusion
by distinguishing between material objects and
the ideas by means of which we perceive them.
·
(perceiver-----ideas-----material objects)
But the representationalist
approach can provide no reliable account of the connection between ideas and
the objects they are supposed to represent. The results of this failure,
Berkeley believed, are bound to be skepticism and atheism.
There is, however,
an obvious alternative. Common sense dictates that there are only two crucial
elements involved in perception: the perceiver and what is perceived. All we
need to do, Berkeley argued, is eliminate the absurd, philosophically-conceived
third element in the picture: that is, we must acknowledge that there are no
material objects. For Berkeley, only the ideas we directly perceive are real.
·
(perceiver----------ideas)
Immaterialism
is the only way to secure common sense, science, and religion against the
perils of skepticism.
Developing the basis
for an empiricist immaterialism requires unlearning significant portions of
what Locke taught us. Berkeley devoted the lengthy "Introduction" of
his Principles of Human Knowledge to a detailed refutation of
what he supposed to be one of Locke's most harmful mistakes, the belief that general terms signify
abstract ideas.
As Berkeley
correctly noticed, our experience is always of concrete particulars. When I
contemplate the idea of "triangle," the image that comes to mind is
that of some determinate shape; having the abstract image of a three-sided
figure that is neither equilateral nor isoceles nor scalene is simply
impossible. (Principles: Intoduction 10) It is unnecessary, too: for
purposes of geometrical reasoning, any particular image can be used as a
representative for all. (It is not at all clear that even Locke would have
disagreed with this position.)
But the consequence of
Berkeley's criticism is a theory of meaning entirely different from Locke's.
General terms (or words of any sort) need not signify ideas of their own, on
Berkeley's view. Instead, they acquire meaning by a process of association with
particular experiences, which are in turn associated with each other. But of
course mere association (as Locke himself had noted with respect to ideas) is
not a reliable guide to reality.
As the
self-proclaimed defender of common sense, Berkeley held that what we perceive
really is as we perceive it to be. But what we perceive are just sensible
objects, collections of sensible qualities, which are themselves nothing other
than ideas in the minds of their perceivers. In the Dialogues Berkeley used Lockean arguments about the
unreliability of secondary qualities in support of his own, more radical view.
Take heat, for
example: does it exist independently of our perception of it? When exposed to
great heat I feel a pain that everyone acknowledges to be in me, not in the
fire, Berkeley argued, so the warmth I feel when exposed to lesser heat must
surely be the same. What is more, if dip both of my hands into a bowl of tepid
water after chilling one and warming the other, the water will feel both warm
and cold at the same time. Clearly, then, heat as I perceive it is nothing
other than an idea in my mind.
Similar arguments
and experiments establish that other sensible qualities—colors that vary with
changes in ambient light, tastes and smells that change perceptibly when I have
a cold, and sounds that depend for their quality on the position of my ears and
conditions in the air—are, like heat, nothing but ideas in my mind. But the
same considerations apply to primary qualities as
well, Berkeley pointed out, since my perception of shape and size depend upon
the position of my eyes, my experience of solidity depends upon my sense of
touch, and my idea of motion is always relative to my own situation. Locke was
correct in his view of primary qualities but mistaken about primary qualities:
all sensible qualities are just ideas.
But sensible objects are
nothing more than collections of sensible qualities, so they are merely complex
ideas in the minds of those who perceive them. For such ideas, Berkeley held,
to be just is to be perceived (in Latin, esse est percipi).
There is no need to refer to the supposition of anything existing outside our
minds, which could never be shown to resemble our ideas, since "nothing
can be like an idea but an idea." Hence, there are no material objects.
Locke's reference to
an "unknown substratum" in which the features of material substances
inhere is a pointless assumption, according to Berkeley. Since it is the very
nature of sensible objects to be perceived, on his view, it would be absurd to
suppose that their reality depends in any way upon an imperceptible core. This
gives rise to a perfectly general argument against even the possibility of
material substance.
Putting aside all of
the forgoing lines of argument, Berkeley declared, the whole issue can be
allowed to rest on a single question: is it possible to conceive of a sensible
object existing independently of any perceiver? The challenge seems easy enough
at first. All I have to do is think of something so remote—a tree in the middle
of the forest, perhaps—that no one presently has it in mind. But if I conceive
of this thing, then it is present in my mind as I think of it, so it is not
truly independent of all perception.
According to Berkeley (and
such later idealists as Fichte
and Bradley) this
argument shows irrefutably that the very concept of material substance as a
sensible object existing independently of any perception is incoherent. No
wonder the representationalist philosophy leads to skepticism: it introduces as
a necessary element in our knowledge of the natural world a concept that is
literally inconceivable!
Although he
maintained that there can be no material substances, Berkeley did not reject the
notion of substance
altogether. The most crucial feature of substance is activity, he supposed, and
in our experience the most obvioius example activity is that of perceiving
itself. So thinking substances do exist, and for these spirits (or souls or
minds) to be is just to perceive (in Latin, esse est percipere).
Like Descartes
and Leibniz, Berkeley held that each spirit is a simple,
undivided, active being whose sole function is to think—that is, to have ideas
such as those of sensible objects. Although each spirit is directly aware of
its own existence and nature, it cannot be perceived. Since ideas are always of
sensible qualities or objects for Berkeley, we have no ideas (but only notions)
of spirits. This is a complete enumeration of what is real: active thinking
substances and their passive ideas.
Strange though Berkeley's
immaterialism may seem, it offers many clear advantages. It is a genuinely
empiricist philosophy, since it begins with what we actually experience and
claims to account for everything without making extravagant suppositions about
unknowable entities. Next, we will consider how well this doctrine provides for
common sense, science, and religion.
Is Berkeley's
immaterialism a reasonable view? He claimed to defend common sense against
skeptical challenges, yet he maintained that sensible objects exist only in the
minds of those who perceive them. Surely common sense includes the belief that
ordinary things continue to exist when I am not perceiving them. Although all
of my visual ideas disappear and reappear every time I blink my eyes, I do not
suppose that the everything I see pops out of existence and then back in. While
a strict phenomenalist
might point out that there is no practical consequence even if it does,
Berkeley disagreed.
The existence of
what I see does not depend exclusively on my seeing it. Berkeley's central
claim is that sensible objects cannot exist without being perceived, but he did
not suppose that I am the only perceiver. So long as some sentient being, some
thinking substance or spirit, has in mind the sensible qualities or objects at
issue, they do truly exist. Thus, even when I close my eyes, the tree I now see
will continue to exist, provided that someone else is seeing it.
This difference,
Berkeley held, precisely marks the distinction between real and imaginary
things. What I merely imagine exists in my mind alone and continues to exist
only so long as I think of it. But what is real exists in many minds, so it can
continue to exist whether I perceive it or not. (That's why, unsure of the
reality of what I seem to see, I may ask someone else, "Did you see
that?") The existence
of sensible objects requires that they be perceived, but it is not dependent
exclusively on my perception of them.
In fact, the
persistence and regularity of the sensible objects that constitute the natural
world is independent of all human perception, according to Berkeley. Even when
none of us is perceiving this tree, god is. The mind of god serves as a
permanent repository of the sensible objects that we perceive at some times and
not at others. (Although Berkeley took great pains to deny it, this view of the
divine role in perception is very similar to Malebranche's notion of
"seeing all things in god.")
So Berkeley's philosophy
can claim to defend common sense. It emphasizes that bodies or sensible objects
really are just the ideas we have of them, yet can also explain their apparent
independence of our perception. All he rejects is the mysterious philosophical
notion of the material
object as an extended substance capable of existing independently of any
perception. That suppostion, he argued, is both unnecessary and untenable.
Even if we accept it
as common sense, is Berkeley's immaterialism compatible with modern science?
Certainly Galileo's
astronomy, Newtonian
mechanics, and the chemistry of Boyle all took for
granted the existence and operation of physical objects. But Berkeley
maintained that natural science, if properly conceived, could proceed and even
thrive without assuming that bodies are material substances existing outside
the mind.
Astronomy and optics
seem to suppose that what we see exists at some distance from us. But Berkeley
argued in his New Theory of Vision that our apparent perception of
distance itself is a mental invention, easily explained in terms of the content
of visual ideas, without any reference to existing material objects. In fact,
Berkeley held, our visual and tactile perceptions are entirely independent.
What we see and what we touch have nothing to do with each other; we have
merely learned by experience to associate each with the other, just as we have
learned to associate the appearance, the taste, and the smell of an apple.
There is no reason to suppose that all of these qualities inhere in a common
material substratum.
It follows that Locke
was mistaken in supposing that our ideas of primary qualities have a special
status because they arise from more than one of our senses. Although the corpuscularian
hypothesis has yielded interesting results so far, Berkeley believed that
science will soon enough outgrow it, learning to rely more directly on what we
perceive for its hypotheses about what new experiences we rightly anticipate.
As we've already
seen, Berkeley accounted for the persistence of bodies in terms of god's
continuing perception of them. The causal regularities we observe in the
natural world rely upon the same source. God's mind is an orderly one, and the
apparent structures of space, time, and causality are nothing more than our
awareness of the divine provision for our welfare. Natural science has plenty
to do even in the absence of material objects, then: it is nothing less than a
systematic exploration of the mind of god. (Here Berkeley came very close to
the philosophy of Malebranche.)
More significantly for us,
he also correctly anticipated much of the physical science of the twentieth
century. Like Berkeley, we believe that the solidity of bodies is merely
apparent, that a proper cosmology depends upon our capacity to conceive it, and
that the role of science is to gather and correlate the independent observations
of human perceivers. It is not surprising that physicists like Mach expressed an
appreciation for the thought of Berkeley.
The affinity between
immaterialism and traditional religion is somewhat easier to understand. Materialism leads to atheism no less than
to skepticism,
Berkeley believed, since its belief that bodies exist outside the mind
encourages the notion that the physical realm may always have existed
independently of any spiritual influence. Immaterialism, by contrast, restores
god to a role of central importance, not only as the chief among active
thinking substances but also as the source of all sensible objects.
God's existence is made
evident by everyday instances of perception, according to Berkeley. Since
sensible objects are mind-dependent yet exhibit a persistence and regularity
that transcends our perception of them, it follows that there must be a
master-perceiver, god, in whose mind they always are. Thus, in the Dialogues,
Philonous extols the beauty and majesty of the natural world, attributing them
to the power and elegance of the divine mind. This leads to the traditional
conception of god as deserving of worship because of the benevolent creation of
all that we observe.
All in all, Berkeley developed a philosophical system worthy of no little
respect. Immaterialism rests on the simple premise that there are no physical
objects. Berkeley defended this notion with many clever arguments and worked
out its implications consistently. Allthough counter-intuitive, immaterialism
is difficult to refute.
Later in eighteenth century,
Scottish philosopher David Hume sought to develop more fully the consequences
of Locke's cautious empiricism by applying
the scientific methods of observation to a study of human nature itself. We
cannot rely on the common-sense pronouncements of popular superstition, which
illustrate human conduct without offering any illumination, Hume held, nor can
we achieve any genuine progress by means of abstract metaphysical
speculation, which imposes a spurious clarity upon profound issues. The
alternative is to reject all easy answers, employing the negative results of philosophical skepticism
as a legitimate place to start.
Stated more positively,
Hume's position is that since human beings do in fact live and function in the
world, we should try to observe how they do so. The key principle to be applied
to any investigation of our cognitive capacities is, then, an attempt to
discover the causes of human belief. This attempt is neither the popular
project of noticing and cataloging human beliefs nor the metaphysical effort to
provide them with an infallible rational justification. According to Hume, the
proper goal of philosophy is simply to explain why we believe what we
do. His own attempt to achieve that goal was the focus of Book I of the Treatise
of Human Nature and all of the first Enquiry.
Hume's analysis of
human belief begins with a careful distinction among our mental contents: impressions
are the direct, vivid, and forceful products of immediate experience; ideas
are merely feeble copies of these original impressions. (Enquiry
II) Thus, for example, the background color of the screen at which I am now
looking is an impression, while my memory of the color of my mother's hair is
merely an idea. Since every idea must be derived from an antecedent impression,
Hume supposed, it always makes sense to inquire into the origins of our ideas
by asking from which impressions they are derived.
To this beginning,
add the fact that each of our ideas and impressions is entirely separable from
every other, on Hume's view. The apparent connection of one idea to another is
invariably the result of an association that we manufacture ourselves. (Enquiry
III) We use our mental operations to link ideas to each other in one of
three ways: resemblance, contiguity, or cause and effect. (This animal looks
like that animal; this book is on that table; moving this switch turns off the
light, for example.) Experience provides us with both the ideas themselves and
our awareness of their association. All human beliefs (including those we
regard as cases of knowledge) result from repeated applications of these simple
associations.
Hume further distinguished
between two sorts of belief. (Enquiry
IV i) Relations of ideas are beliefs grounded wholly on associations
formed within the mind; they are capable of demonstration because they have no
external referent. Matters of fact are beliefs that claim to report the
nature of existing things; they are always contingent. (This is Hume's version
of the a priori
/ a posteriori distinction.) Mathematical and logical knowledge
relies upon relations of ideas; it is uncontroversial but uninformative. The
interesting but problematic propositions of natural science depend upon matters
of fact. Abstract metaphysics mistakenly (and fruitlessly) tries to achieve the
certainty of the former with the content of the latter.
Since genuine
information rests upon our belief in matters of fact, Hume was particularly
concerned to explain their origin. Such beliefs can reach beyond the content of
present sense-impressions and memory, Hume held, only by appealing to presumed
connections of cause and effect. But since each idea is distinct and separable
from every other, there is no self-evident relation; these connections can only
be derived from our experience of similar cases. So the crucial question in epistemology is to ask
exactly how it is possible for us to learn from experience. (Enquiry
IV ii)
Here, Hume supposed,
the most obvious point is a negative one: causal reasoning can never be
justified rationally. In order to learn, we must suppose that our past
experiences bear some relevance to present and future cases. But although we do
indeed believe that the future will be like the past, the truth of that belief
is not self-evident. In fact, it is always possible for nature to change, so
inferences from past to future are never rationally certain. Thus, on Hume's
view, all beliefs in matters of fact are fundamentally non-rational. (Enquiry
V i)
Consider Hume's favorite
example: our belief that the sun will rise tomorrow. Clearly, this is a matter
of fact; it rests on our conviction that each sunrise is an effect caused by
the rotation of the earth. But our belief in that causal relation is based on
past observations, and our confidence that it will continue tomorrow cannot be
justified by reference to the past. So we have no rational basis for believing
that the sun will rise tomorrow. Yet we do believe it!
Skepticism quite
properly forbids us to speculate beyond the content of our present experience
and memory, yet we find it entirely natural to believe much more than that.
Hume held that these unjustifiable beliefs can be explained by reference to
custom or habit. That's how we learn from experience. When I observe the
constant conjunction of events in my experience, I grow accustomed to
associating them with each other. (Enquiry
V ii) Although many past cases of sunrise do not guarantee the future of
nature, my experience of them does get me used to the idea and produces in me
an expectation that the sun will rise again tomorrow. I cannot prove that it
will, but I feel that it must.
Remember that the
association of ideas is a powerful natural process in which separate ideas come
to be joined together in the mind. Of course they can be associated with each
other by rational means, as they are in the relations of ideas that constitute
mathematical knowledge. But even where this is possible, Hume argued, reason is
a slow and inefficient guide, while the habits acquired by much repetition can
produce a powerful conviction independently of reason. Although the truth of
"9 × 12 = 108" can be established rationally in principle, most of us
actually learned it by reciting our multiplication tables. In fact, what we
call relative probability is, on Hume's view, nothing more than a measure of
the strength of conviction produced in us by our experience of regularity.
Our beliefs in matters of
fact, then, arise from sentiment or feeling rather than from reason. For Hume,
imagination and belief differ only in the degree of conviction with which their
objects are anticipated. Although this positive answer may seem disappointing,
Hume maintained that custom or habit is the great guide of life and the
foundation of all natural science.
According to Hume,
our belief that events are causally related is a custom or habit acquired by
experience: having observed the regularity with which events of particular
sorts occur together, we form the association of ideas that produces the habit
of expecting the effect whenever we experience the cause. But something is
missing from this account: we also believe that the cause somehow produces
the effect. Even if this belief is unjustifiable, Hume must offer some
explanation for the fact that we do hold it. His technique was to search for
the original impression from which our idea of the necessary connection between
cause and effect is copied. (Enquiry
VII)
The idea does not
arise from our objective experience of the events themselves. All we observe is
that events of the "cause" type occur nearby and shortly before
events of the "effect" type, and that this recurs with a regularity
that can be described as a "constant conjunction." Although this
pattern of experience does encourage the formation of our habit of expecting
the effect to follow the cause, it includes no impression of a necessary
connection.
Nor do we acquire
this impression (as Locke had supposed) from our own capacity for voluntary
motion. Here the objective element of constant conjunction is rarely
experienced, since the actions of our minds and bodies do not invariably submit
to our voluntary control. And even if volition did always produce the intended
movement, Hume argued, that would yield no notion of the connection between
them. So there is no impression of causal power here, either.
Still, we do have the idea
of a necessary connection, and it must come from somewhere. For a
(non-justificatory) explanation, Hume refers us back to the formation of a
custom or habit. Our (non-rational) expectation that the effect will follow the
cause is accompanied by a strong feeling of conviction, and it is the
impression of this feeling that is copied by our concept of a necessary
connection between cause and effect. The force of causal necessity is just the
strength of our sentiment in anticipating efficacious outcomes.
In a notorious
passage of the Treatise, Hume offered a similar account of the belief in
the reality of the self. Here there is the ordinary human supposition that lies
behind our use of first-personal pronouns. Upon this relatively simple
foundation, philosophers have erected the notion of an immaterial substance, a
mind or soul that persists through time on its own. Hume's question is,
"From what antecedent impression does the idea of the self arise?"
Hume pointed out
that we do not have an impression of the self. No matter how closely I
attend to my own experience, no matter how fully I notice the mental operations
presently occurring "in my mind," I am never directly aware of
"I." What I do experience is a succession of separate and individual
ideas, associated with each other by relations of resemblance and causality.
Although these relations may be extended through time by memory, there is no
evidence of any substantial ground for their coherence. The persistent self and
the immortal soul are philosophical fictions.
To suppose otherwise, Hume
held, is to commit a category mistake: the self is just a bundle of
perceptions, like the railroad cars in a train; to look for a self beyond the
ideas would be like looking for a train beyond the cars. Our idea of a
persistent self is simply a result of the human habit of attributing continued
existence to any collection of associated parts. Like our idea of the necessary
connection of cause with effect, belief in our own reality as substantial
selves is natural, but unjustifiable.
Another perfectly
ordinary feature of human cognition is our belief in the reality of the
external world. As I write this lesson, I readily suppose that my fingers are
touching a keyboard, that the sun is shining outside and that the radio is
playing a Clapton song. In Hume's skeptical philosophy, what is the status of
these beliefs?
The primitive human
belief, Hume noted, is that we actually see (and hear, etc.) the physical
objects themselves. But modern philosophy and science have persuaded us that
this is not literally true. According to representationalists,
we are directly aware of ideas, which must in turn be causally produced in our
minds by external objects. The problem is that on this view we can never know
that there really are physical objects that produce our sensory ideas.
We cannot rely on
causal reasoning to convince us that there are external objects, Hume argued,
since (as we have just seen) such reasoning arises from our observation of a
constant conjunction between causes and effects. But according to the representationalist
philosophy, we have no direct experience of the presumed cause! If we know
objects only by means of ideas, then we cannot use those ideas to establish a
causal connection between the things and the objects they are supposed to
represent.
In fact, Hume supposed, our
belief in the reality of an external world is entirely non-rational. (Enquiry
XII i) It cannot be supported either as a relation of ideas or even as a
matter of fact. Although it is utterly unjustifiable, however, belief in the
external world is natural and unavoidable. We are in the habit of supposing
that our ideas have external referents, even though we can have no real evidence for doing so.
Representationalism thusly implodes: the ideas, originally introduced as
intermediaries between perceivers and things, end up absorbing both, rendering
everything but themselves superfluous.
Where does this
leave us? Hume believed himself to be carrying out the empiricist program with
rigorous consistency. Locke honestly proposed the possibility of deriving
knowledge from experience, but did not carry it far enough. Bayle
and Berkeley noticed further implications. Now Hume has shown
that empiricism inevitably leads to an utter and total skepticism.
According to Hume,
knowledge of pure mathematics is secure because it rests only on the relations
of ideas, without presuming anything about the world. Experimental observations
(conducted without any assumption of the existence of material objects)
permit us to use our experience in forming useful habits. Any other
epistemological effort, especially if it involves the pretense of achieving
useful abstract knowledge, is meaningless and unreliable.
The most reasonable
position, Hume held, is a "mitigated" skepticism that humbly accepts
the limitations of human knowledge while pursuing the legitimate aims of math
and science. (Enquiry XII 3) In our non-philosophical moments, of
course, we will be thrown back upon the natural beliefs of everyday life, no
matter how lacking in rational justification we know them to be.
Having examined the
epistemological basis for Hume's naturalism, we are ready to consider its
application to human conduct. In morality as in all else, Hume supposed, our
beliefs and actions are the products of custom or habit. Since all of our most
scientific beliefs have exactly the same foundation, this account preserves the
natural dignity of moral judgments.
Hume devoted the
second book of the Treatise to an account of the human passions and a
discussion of their role in the operation of the human will. It is our feelings
or sentiments, Hume claimed, that exert practical influence over human volition
and action. Observation does reveal a constant conjunction between having a
motive (not a reason) for acting and performing the action in question. Hence,
with the same reliability that characterizes our belief in any causal relation,
on Hume's view, we further believe that our feelings have the power to result
in actions.
At one level, of
course, this entails that we are determined to act as we do. Our feelings or
sentiments produce our actions with the same degree of causal necessity, the
same habitual expectation that the future will resemble the past, as that by
which the rotation of the earth causes the sun to rise. (Like Locke, Hume
denied that determination of this sort is relevant to our moral freedom; only when my
actions are observed to be the effects of some cause outside myself could I
decline to accept my own responsibility for them.) So a proper science of human
nature will account for human actions, as well as for human beliefs, by
reference to the natural formation of habitual associations with human
feelings.
Clearly, rationality had no
place in this account of morality. Although reason may judge relations of ideas
and matters of fact, its most vivid outcomes never compel us to act as even the
weakest of feelings may do. No compilation of facts, however complete or
reliable, ever entails a moral obligation or results in action. "Reason
is, and ought to be, only the slave of the passions," Hume held. All human
actions flow naturally from human feelings, without any interference from human
reason.
It does not follow
that all actions are of equal value. On Hume's view, the judgments and
recommendations of traditional morality arise not from reason, but from a moral sense. As a
straightforward matter of fact (discoverable by experience), virtue is always
accompanied by a feeling of pleasure, and vice by a feeling of pain. Thus, we
praise an instance of virtuous action precisely because it arouses in us a
pleasant feeling, and we avoid committing a vicious action because we
anticipate that doing so would produce pain. Our feelings provide a natural
guide for moral conduct.
Hume worked out the
details of this account in Book III of the Treatise. The ideas of
benevolence, utility, and justice arouse our deepest and most pervasive
feelings, he maintained, and these feelings in turn motivate us toward actions
of moral worth. I offer assistance to those in need because it makes me feel
good to do so, and I am fair in my dealings with others because it would make me
feel bad if I were not. All of morality rests firmly upon the natural human
inclination to seek pleasure and avoid pain.
This noncognitive
derivation of morality from emotion rather than from reason may seem hopelessly
subjective at first glance, but remember that on Hume's view our confidence in
causal efficacy has a similar source. I do what is morally right in the same
way that I believe there is an external world—by following my natural
inclinations in the absence of rational evidence. Thus, Hume regarded himself
as having provided morality with a status no less significant in human life
than that of natural science.
Finally, we pause
for a quick look at Hume's views on religion. In his own time, he was often
regarded as a great enemy of organized religion. The posthumously published Dialogues
offer an extended treatment of the intellectual interchanges among facile
orthodoxy, natural theology, and philosophical skepticism. There Hume took
great care to expose what he believed to be the great mistake of trying to
prove that god exists.
The newly-popular argument from design
supposes that the order and beauty of the universe reflect the greatness and
demonstrate the reality of its ultimate cause. Hume noted that since this
analogical argument claims to infer a cause from presumed effects, it must be
grounded as a matter of fact on the experience of a constant conjunction. But
since in fact we have not observed repeated instances of gods creating
universes, we cannot have formed the habit of associating our experience of the
one with our inferences about the other. No causal relationship can ever be
established from the observation of a unique example.
What is more, Hume argued
that even if it were possible to engage in causal reasoning in this case, it
could not warrant the intended conclusion. The presumed cause must always be
supposed to be proportional to the observed effect, so the manifest
imperfections of this world could never support belief in the perfection of its
creator. The argument from design is a two-edged sword, as likely to persuade
us of the frailty or malevolence as of the power and benevolence of the
presumed cause of the world as we know it.
Nor did Hume suppose
that references to the miraculous would provide a rational basis for religion.
In this case, we do have the experience of constant conjunction to establish
the "laws of nature" of which any purported miracle is a violation,
and we have only the testimony of witnesses to establish the fact of the
miracle itself. Since this testimony and the motives of the witnesses who offer
it are always open to question, Hume argued, we will believe that the miracle
occurred only when the possibility of false testimony seems an even greater
violation of the natural order.
Some scholars suppose that
the final paragraph of the essay "On Miracles" (Inquiry
Section X) and the closing words of the Dialogues reflect Hume's
acceptance of religious fideism,
the notion that religion is properly a matter of faith, not reason. On this
view, a fideistic Hume could hold that belief in the existence of god or the
immortality of the soul is no less natural than belief in the existence of
bodies or the persistence of the self. An alternative interpretation, however,
accepts the lengthy rejection of religious orthodoxy as sincere while
attributing the brief, moderate endings as a half-hearted effort to take the
edge off. Certainly Hume's influence on the philosophy of religion has been
primarily of the latter sort.
The major philosophers
with whose work we are primarily occupied represent only a portion of the eighteenth century's
great cultural upheaval, often known as the Enlightenment. A
host of other figures throughout Europe responded to the challenges of life and
thought in ways that are independently interesting, even though they proved to
be somewhat less influential on the philosophical tradition. Among the British,
we continue to see an intense concern with the practical affairs of morality
and politics.
As a professor of moral
science, Adam Smith
defended Hutcheson's
notion of a moral sense
and proposed the application of Hume's
naturalism to the emerging discipline of political economy. His results are
often regarded as the classic statement of the theoretical foundations for
modern capitalism. Richard
Price expressed many similar concerns. But William Paley, on the
other hand, rejected the intuitionistic approach
of his contemporaries. Paley grounded morality as a rational consequence of
natural theology based on the teleological argument
for the existence of god.
Mary
Wollstonecraft defended the principles of the French revolution
and argued that women were no less rational and therefore as deserving of
educational and economic opportunity as men.
Scottish professor Thomas Reid believed
that Hume's skepticism
demonstrated the abject failure of its representationalist origins. On Reid's
view, we should reject the entire "way of ideas" and adopt the
straightforward realism
of common sense. Sense perception, then, is a direct relation between the
perceiver and an existing external object; apparent cases of illusion must be
resolved by appeal to the distinction between primary and secondary
qualities. Although it is now little remembered, Reid's thought was greatly
influential in Britain and the United States for more than a century.
Among Germans, the
Enlightenment was studiously academic. Development of the German universities
fostered a preference for synoptic philosophizing: the goal of German
philosophers was often to combine rational and empirical elements in a single
comprehensive system. Both Leibniz and Christian Wolff had
tried to develop complete metaphysical systems that could explain the phenomena
of nature in rationalistic
terms. Lessing
fondly recalled the metaphysical monism of Spinoza,
and Moses Mendelssohn
mounted a lofty defense of the immortality of the human soul. But many of these
efforts ignored the force of Hume's
skeptical arguments, rather than responding to them constructively. The
greatest philosopher of the German Enlightenment, Immanuel Kant,
took a different approach.
In France, the skepticism promoted by
Bayle helped to promote opposition to the church and to
encourage political revolution. The Encyclopedists and
"free-thinkers" of the eighteenth-century sought to undermine
confidence in established social positions of every sort. Voltaire's, for
example, was a brilliantly mocking voice that aimed to deflate any and all
claims of certitude. If we agree that god exists, he supposed, we must then
face the severe difficulties presented by the existence of evil in the world.
(In Candide Voltaire savagely attacked the practical consequences of Leibniz's
claim that this is "the
best of all possible worlds.") If we suppose that morality is vital
for human life, we must somehow learn to deal with the evident determination of
the will. Above all, Voltaire bitterly rejected all claims of social or
religious authority.
Swiss philosopher Jean-Jacques
Rousseau also harbored a profound dislike for authority (or
even structure) of any sort and sought to restore a proper respect for the
creativity and worth of individual human beings. But Rousseau also explored the
political implications of these ideas: his notion of individual liberty and his
convictions about political unity helped to fuel the romantic spirit of the
French Revolution.
In the second of his
essays for the Dijon competition, the Discours sur
l'origine et les fondements de l'inégalité parmi les hommes (Discourse on the
Origin of Inequality) (1755), Rousseau emphasized that the natural
condition of humanity is disguised by the corruptive influence of civilization.
Reliance on the feeling of compassion and on native respect for sentience, he
believed, was an adequate guide for human life.
Although some few
natural inequalities among individual human beings are inevitable, Rousseau
argued that the far more significant moral and political inequalities are
purely conventional in origin. Savage human beings, like animals of any
species, are well-adapted by nature to their surroundings in the natural world.
In the absence of any discursive reasoning about themselves, such beings have
no need for morality or a concept of duty. Their lives are wholly guided by
their feelings of pity and love for each other, and conventional inequalities
do not arise.
It is concern for private
property, according to Rousseau, that gives rise to civil society. Everyone's
well-being is served by reliance on each other in the basic cooperation that
characterizes the family as a primitive social unit, designed to secure the
necessities of human life. But the very success of this cooperative effort
produces time for leisure, which in turn leads to the production of agriculture
and industry. These developments require ownership of land and promote
acquisition of wealth, both of which entail the protection of a stable
government. Thus, Rousseau held, a body politic must be established by means of
a contract that unites many wills into one.
The details of this
process Rousseau described in Du contrat
social (On the Social
Contract) (1762). At the outset, Rousseau notes that since perfect
freedom is the natural condition of human beings, it is the existence of social
restrictions that requires explanation. Only the family is truly a natural
association, and its features are commonly extended far beyond the basic needs
from which it arises. Military conquest and slavery in its usual forms cannot
establish any genuine right for one person to rule over another. So, Rousseau
concluded, society must devolve from a social contract in
which individual citizens voluntarily participate.
Each citizen chooses to
trade the natural liberty of independent life for the civil liberty secured by
the state, allowing social rights over property to outweigh individual rights.
But according to Rousseau, this surrender of each to the good of the whole must
take place in a way that also secures the unity of all in a desire for what
will most benefit the whole. "Trouver
une forme d'association qui défende et protège de toute la force commune la
personne et les biens de chaque associé, et par laquelle chacun s'unissant à
tous n'obéisse pourtant qu'à lui-même et reste aussi libre qu'auparavant." This is the fundamental problem of all social
organization: to secure the participation of every individual in the general
will.
As Rousseau envisioned
it, the general will
[Fr. volonté
générale] is not merely the cancelled-out sum of all the individual
wills of those who participate in the social contract, the will of all [Fr. volonté
de tous]. Indeed, he warned that the influence of parties representing
special interests is directly inimical to the sort of sound public deliberation
that can arrive at a consensus regarding the welfare of all. So thoroughly must
each individual surrender to the whole as to acknowledge that "sa vie n'est plus seulement un bienfait de la
nature, mais un don conditionnel de l'Etat". By entering into the original agreement, I have sworn
to seek only the welfare of the community, no matter what the consequences may
be for me. The general will must be concerned solely with the general interest,
which is the inalienable responsibility of the sovereign body, expressed
through legislation.
Although the general
will must be arrived at through reasoned deliberation in the state as a whole,
its execution depends upon an embodiment in the structure of government. Thus,
for Rousseau, distinct forms of government have to do only with the execution of
the sovereign laws: democracy is dangerous in application to particular cases,
where the general will can easily be lost in the pressure of private interests;
aristocracy is acceptable so long as it executes the general will rather than
serving the welfare of the ruling elite; and monarchy clearly raises the
temptation to serve private welfare at the expense of the common good. The
appropriate form of government for any state depends upon the character of its
people and even its physical climate, Rousseau supposed, and its success can be
measured easily by the extent to which its population thrives.
Abuses of power can,
of course, threaten the very life of the state. When the government—properly
responsible only for carrying out the general will—takes upon itself the
sovereign responsibility of establishing legal requirements for the people, the
social contract has been broken. For Rousseau, then, the establishment of a
government is always provisional and temporary, subject to the continual review
by its citizens. Since the legitimacy of the social contract depends upon the
unanimous consent of all the governed, the sovereign general will is fully
expressed only in an assembly of the entire population. Even the effort to
establish a representative legislative body is an illusion, according to
Rousseau, since the general will can be determined only by each for all.
The general will,
abstractly considered as a commitment to the welfare of the whole, is
indestructible in principle, Rousseau held, even though it may be overridden by
undesirable motives in practice. The original contract requires perfect
unanimity, and major issues should be decided by a major portion of the
population, but simple matters requiring quick action may be determined by a
simple majority. In each case, Rousseau supposed that open inquiry and debate
will converge on an awareness by each individual of what is truly in the best
interest of the community as a whole; and that is the general will. Positions
of leadership that require skill should be decided by election, while those
that demand only good sense should be chosen by lot.
In a final reminder of the
nature of the general will, Rousseau noted that it is distinct from the social
customs that may be endorsed or expressed as public opinion. These are not
determinations of what is best for all, but merely codifications of the
conventional mores of the people, and should occupy a correspondingly lesser
status. Even when incorporated into the civil religion, with an appeal to the
full force of divine as well as human approval, he insisted, social customs are
merely that.
Next we turn to the
philosophy of Immanuel Kant, a watershed figure who forever altered the
course of philosophical thinking in the Western tradition. Long after his
thorough indoctrination into the quasi-scholastic German appreciation of the
metaphysical systems of Leibniz and Wolff, Kant said, it
was a careful reading of David Hume that "interrupted my dogmatic slumbers
and gave my investigations in the field of speculative philosophy a quite new
direction." Having appreciated the full force of such skeptical arguments,
Kant supposed that the only adequate response would be a "Copernican
Revolution" in philosophy, a recognition that the appearance of the
external world depends in some measure upon the position and movement of its
observers. This central idea became the basis for his life-long project of
developing a critical philosophy that could withstand them.
Kant's aim was to
move beyond the traditional dichotomy between rationalism and empiricism. The rationalists had tried
to show that we can understand the world by careful use of reason; this
guarantees the indubitability of our knowledge but leaves serious questions
about its practical content. The empiricists, on the
other hand, had argued that all of our knowledge must be firmly grounded in
experience; practical content is thus secured, but it turns out that we can be
certain of very little. Both approaches have failed, Kant supposed, because
both are premised on the same mistaken assumption.
Progress in philosophy,
according to Kant, requires that we frame the epistemological problem in an
entirely different way. The crucial question is not how we can bring ourselves
to understand the world, but how the world comes to be understood by us.
Instead of trying, by reason or experience, to make our concepts match the
nature of objects, Kant held, we must allow the structure of our concepts shape
our experience of objects. This is the purpose of Kant's Critique of Pure
Reason (1781, 1787): to show how reason determines the conditions under
which experience and knowledge are possible.
In the Prolegomena
to any Future Metaphysic (1783) Kant presented the central themes of the
first Critique in a somewhat different manner, starting from instances
in which we do appear to have achieved knowledge and asking under what
conditions each case becomes possible. So he began by carefully drawing a pair
of crucial distinctions among the judgments we do actually make.
The first
distinction separates a
priori from a posteriori judgments by reference to the origin of
our knowledge of them. A priori judgments are based upon reason
alone, independently of all sensory experience, and therefore apply with strict
universality. A posteriori judgments, on the other hand, must be
grounded upon experience and are consequently limited and uncertain in their
application to specific cases. Thus, this distinction also marks the difference
traditionally noted in logic between necessary and contingent
truths.
But Kant also made a
less familiar distinction between analytic and synthetic
judgments, according to the information conveyed as their content. Analytic
judgments are those whose predicates are wholly contained in their subjects;
since they add nothing to our concept of the subject, such judgments are purely
explicative and can be deduced from the principle of non-contradiction. Synthetic
judgments, on the other hand, are those whose predicates are wholly distinct
from their subjects, to which they must be shown to relate because of some real
connection external to the concepts themselves. Hence, synthetic judgments are
genuinely informative but require justification by reference to some outside
principle.
Kant supposed that previous
philosophers had failed to differentiate properly between these two
distinctions. Both Leibniz
and Hume had made just
one distinction, between matters of fact based on sensory experience and the
uninformative truths of pure reason. In fact, Kant held, the two distinctions
are not entirely coextensive; we need at least to consider all four of their
logically possible combinations:
·
Analytic a posteriori judgments cannot
arise, since there is never any need to appeal to experience in support of a
purely explicative assertion.
·
Synthetic a posteriori judgments are the
relatively uncontroversial matters of fact we come to know by means of our
sensory experience (though Wolff had tried to
derive even these from the principle of contradiction).
·
Analytic a priori judgments, everyone
agrees, include all merely logical truths and straightforward matters of
definition; they are necessarily true.
·
Synthetic a priori
judgments are the crucial case, since only they could provide new information
that is necessarily true. But neither Leibniz nor Hume considered the possibility
of any such case.
Unlike his predecessors,
Kant maintained that synthetic a priori judgments not only are possible
but actually provide the basis for significant portions of human knowledge. In
fact, he supposed (pace Hume) that arithmetic and geometry comprise such
judgments and that natural science depends on them for its power to explain and
predict events. What is more, metaphysics—if it turns out to be possible at
all—must rest upon synthetic a priori judgments, since anything else
would be either uninformative or unjustifiable. But how are synthetic a
priori judgments possible at all? This is the central question Kant sought
to answer.
Consider, for
example, our knowledge that two plus three is equal to five and that the
interior angles of any triangle add up to a straight line. These (and similar)
truths of mathematics are synthetic judgments, Kant held, since they contribute
significantly to our knowledge of the world; the sum of the interior angles is
not contained in the concept of a triangle. Yet, clearly, such truths are known
a priori, since they apply with strict and universal necessity to all of
the objects of our experience, without having been derived from that experience
itself. In these instances, Kant supposed, no one will ask whether or not we
have synthetic a priori knowledge; plainly, we do. The question is, how
do we come to have such knowledge? If experience does not supply the required
connection between the concepts involved, what does?
Kant's answer is
that we do it ourselves. Conformity with the truths of mathematics is a
precondition that we impose upon every possible object of our experience. Just
as Descartes had noted in the Fifth Meditation, the essence
of bodies is manifested to us in Euclidean solid geometry, which determines a
priori the structure of the spatial world we experience. In order to be
perceived by us, any object must be regarded as being uniquely located in space
and time, so it is the spatio-temporal framework itself that provides the
missing connection between the concept of the triangle and that of the sum of
its angles. Space and time, Kant argued in the "Transcendental
Aesthetic" of the first Critique, are the "pure forms of sensible
intuition" under which we perceive what we do.
Understanding
mathematics in this way makes it possible to rise above an old controversy
between rationalists and empiricists regarding the very nature of space and
time. Leibniz had maintained that space and time are not
intrinsic features of the world itself, but merely a product of our minds. Newton, on the other
hand, had insisted that space and time are absolute, not merely a set of
spatial and temporal relations. Kant now declares that both of them were
correct! Space and time are absolute, and they do derive from our minds. As
synthetic a priori judgments, the truths of mathematics are both
informative and necessary.
This is our first instance
of a transcendental
argument, Kant's method of reasoning from the fact that we have knowledge
of a particular sort to the conclusion that all of the logical presuppositions
of such knowledge must be satisfied. We will see additional examples in later
lessons, and can defer our assessment of them until then. But notice that there
is a price to be paid for the certainty we achieve in this manner. Since
mathematics derives from our own sensible intuition, we can be absolutely sure
that it must apply to everything we perceive, but for the same reason we can
have no assurance that it has anything to do with the way things are apart from
our perception of them. Next time, we'll look at Kant's very similar treatment
of the synthetic a priori principles upon which our knowledge of natural
science depends.
In natural science
no less than in mathematics, Kant held, synthetic a priori judgments
provide the necessary foundations for human knowledge. The most general laws of
nature, like the truths of mathematics, cannot be justified by experience, yet
must apply to it universally. In this case, the negative portion of Hume's
analysis—his demonstration that matters of fact rest upon
an unjustifiable belief that there is a necessary connection between causes
and their effects—was entirely correct. But of course Kant's more constructive
approach is to offer a transcendental argument from the fact that we do have
knowledge of the natural world to the truth of synthetic a priori
propositions about the structure of our experience of it.
As we saw last time,
applying the concepts of space and time as forms of sensible intuition is
necessary condition for any perception. But the possibility of scientific
knowledge requires that our experience of the world be not only perceivable but
thinkable as well, and Kant held that the general intelligibility of experience
entails the satisfaction of two further conditions:
First, it must be
possible in principle to arrange and organize the chaos of our many individual
sensory images by tracing the connections that hold among them. This Kant
called the synthetic unity of the sensory manifold.
Second, it must be possible
in principle for a single subject to perform this organization by discovering
the connections among perceived images. This is satisfied by what Kant called
the transcendental unity of apperception.
Experiential knowledge is thinkable only if there is some regularity in what is
known and there is some knower in whom that regularity can be represented.
Since we do actually have knowledge of the world as we experience it, Kant
held, both of these conditions must in fact obtain.
Since (as Hume had
noted) individual images are perfectly separable as they occur within the
sensory manifold, connections between them can be drawn only by the knowing
subject, in which the principles of connection are to be found. As in
mathematics, so in science the synthetic a priori judgments must derive
from the structure of the understanding itself.
Consider, then, the
sorts of judgments distinguished by logicians (in Kant's day): each of them has
some quantity (applying to all things, some, or only one); some quality
(affirmative, negative, or complementary); some relation (absolute,
conditional, or alternative); and some modality (problematic, assertoric,
or apodeictic). Kant supposed that any intelligible thought can be
expressed in judgments of these sorts. But then it follows that any thinkable
experience must be understood in these ways, and we are justified in projecting
this entire way of thinking outside ourselves, as the inevitable structure of
any possible experience.
The result of this
"Transcendental Logic" is the schematized table of categories, Kant's
summary of the central concepts we employ in thinking about the world, each of
which is discussed in a separate section of the Critique:
|
Quantity |
Quality |
|
Unity |
Reality |
|
Plurality |
Negation |
|
Totality |
Limitation |
|
Axioms of Intuition |
Anticipations of Perception
|
|
|
|
|
Relation |
Modality |
|
Substance |
Possibility |
|
Cause |
Existence |
|
Community |
Necessity |
|
Analogies of Experience |
Postulates of Empirical
Thought |
Our most fundamental convictions about the natural world derive from these
concepts, according to Kant. The most general principles of natural science are
not empirical generalizations from what we have experienced, but synthetic a
priori judgments about what we could experience, in which these concepts
provide the crucial connectives.
So Kant maintained
that we are justified in applying the concepts of the understanding to the
world as we know it by making a priori determinations of the nature of
any possible experience. In order to see how this works in greater detail,
let's concentrate on the concepts of relation, which govern how we understand
the world in time. As applied in the Analogies of Experience, each concept of
relation establishes one of the preconditions of experience under one of the modes
of time: duration, succession, and simultaneity.
1. Substance:
The experience of any change requires not only the perception of the altered
qualities that constitute the change but also the concept of an underlying
substance which persists through this alteration. (E.g., in order to know by
experience that the classroom wall has changed in color from blue to yellow, I
must not only perceive the different colors—blue then, yellow now—but also
suppose that the wall itself has endured from then until now.) Thus, Kant
supposed that the philosophical concept of substance (reflected in the
scientific assumption of an external world of material objects) is
an a priori condition for our experience.
2. Cause:
What is more, the experience of events requires not only awareness of their
intrinsic features but also that they be regarded as occurring one after
another, in an invariable regularity determined by the concept of causality.
(E.g., in order to experience the flowering of this azalea as an event, I must
not only perceive the blossoms as they now appear but must also regard them as
merely the present consequence of a succession of prior organic developments.)
Thus, Kant responded to Hume's skepticism by maintaining that the concept of
cause is one of the synthetic conditions we determine for ourselves prior to
all experience.
3. Community:
Finally, the experience of a world of coexisting things requires not only the
experiences of each individually but also the presumption of their mutual
interaction. (E.g., in order believe that the Sun, Earth, and Moon coexist in a
common solar system, I must not only make some estimate of the mass of each but
must also take into account the reciprocity of the gravitational forces between
them.) Thus, on Kant's view, the notion of the natural world as a closed system
of reciprocal forces is another a priori condition for the
intelligibility of experience.
Notice again that these features of nature are not generalized from anything we have already experienced; they are regulative principles that we impose in advance on everything we can experience. We are justified in doing so, Kant believed, because only the pure concepts of the understanding can provide the required connections to establish synthetic a priori judgments. Unless these concepts are systematically applied to the sensory manifold, the unity of apperception cannot be achieved, a