6. PHILOSOPHY AS DOUBT





    Imagine a tree.  Perhaps the drawing I've made here (see Figure 6.1)

will help you to do so (although it will also demonstrate that you don't

have to be an artist in order to be a philosopher!).  Just how is it that

philosophy is like a tree?  There are, in fact, many different possible

ways of applying this analogy.  One interesting way is suggested by the

philosopher whose ideas we shall be discussing today.  He worked out his

own version of the myth on which this course is based, by claiming

philosophy is like a tree in which metaphysics are the roots, physics is

the trunk, and the other sciences are the branches.  In such a case, which

may well have been an accurate reflection of how philosophy functioned in

Descartes' lifetime, the leaves of the tree would probably best be

correlated to knowledge, though Descartes himself did not carry his

analogy this far.  For our purposes here in the first part of this course,

we can accept his explanation, since metaphysics certainly does have a

function similar to the roots of a tree.  By the time we have finished the

first seven lectures, I hope the reasons for this will be clear enough.

Later on, however, I will suggest revisions of some of the other aspects

of Descartes' version of the myth, in order to bring it up to date.



    Rene Descartes (1596-1650) is a name some of you will already be

familiar with, because of the contribution he made to the field of

mathematics.  Not only did he contribute to the further development of

algebra, but he invented the system of coordinate geometry that we all

learned in school.  When he turned his attention towards philosophy, he

recognized an inherent problem in the tradition.  For two thousand years

the systems of Plato and Aristotle, in one form or another, had dominated

virtually all philosophical thinking in the west.  Nearly all philosophers

assumed either a kind of Platonic idealism or a kind of Aristotelian

realism as the starting point of their own philosophizing, though a few

attempted to synthesize these two schools of thought in one way or

another.  What was wrong with these two systems, which prevented further

progress in philosophy?



    Descartes believed the impasse was created by the lack of any

completely certain truth, which could serve as an indisputable starting

point upon which all knowledge (i.e., science) could be constructed.  But

how could such absolute certainty be established?  Neither Plato's method

of dialogue nor Aristotle's teleological method on their own had been able

to produce such a solid foundation for a truly rigorous science.  How then

could such a foundation be discovered?  Descartes hit upon an idea for a

new philosophical method, which he believed would enable us to reach such

certainty once and for all.  His new discovery was the method of doubt.

By systematically doubting everything we know about our world and our

selves, he hoped he might come across something that would be impossible

to doubt.  This could then serve as an absolutely certain starting point

for building a positive philosophical system.



    What then can we doubt?  How about our senses?  Can you trust your

senses? One day, not long after moving to Hong Kong, my wife and I were

shopping in a local mall.  It was getting quite late, so we started

looking for a place to eat.  As we walked into one of the supermarkets in

that mall I noticed at a distance a very nice display of Japanese food on

sale.  I was quite hungry, so my mouth began watering immediately.  We

agreed to try eating at this place, though it was rather crowded.  As we

came closer I was really impressed by the apparently high quality of the

meals they had on display.  Only when we reached the counter itself did I

realize that the food on display was not food at all, but plastic!  My

senses had been utterly fooled by the ingenuity of some marketing agent.

And by your laughter I can tell that many of you have made the same

mistake.



[Figure 6.1:  Descartes' Tree of Philosophy]



    In the first of the six "meditations" described in Meditations on

First Philosophy, Descartes began his quest for certainty by using the

virtually universal experience of being fooled in this way to cast doubt

on the reliability of our senses.  If we were fooled in that one instance,

how do we know we have not been fooled more often?  Indeed, if any given

impression our senses are now giving to us might be a false impression,

then there seems to be no possibility of discovering anything certain in

our senses.  This discredits Aristotelian realism, since it is based on

the assumption that substances, which we perceive primarily with our

senses, are ultimately real.



    What about our ideas?  Perhaps Plato was right after all, and our

ideas are the proper foundation for all knowledge.  But Descartes found it

just as easy to cast doubt in this realm as well.  Even ideas that seem to

us to be certain, ideas most people would never think of doubting, can be

doubted if we try.  For example, there would be many ways of casting doubt

on the spatial and temporal character of our everyday experience.  Most of

us have experienced dreams in which spatial laws such as gravity do not

apply in the usual way (e.g., when we fly in our dreams) or dreams in

which time seems to go slower or faster than when we are awake.  How do we

know our everyday experience is not just a dream, from which we will wake

up any minute now?  Perhaps there is an evil demon who is deceiving us all

into mistaking this long dream for our real world.  Even if there is no

such demon, we have all had the experience of suddenly realizing that some

idea we have held to be true for a long time is actually false.  Any

single idea might turn out to be an illusion of this kind, so what is to

prevent all our ideas from being illusory?  Hence, Plato's idealism is of

no more use than Aristotle's realism in our search for something

absolutely certain.



    What about mathematics?  Descartes himself was a mathematician, and

certainly believed that mathematics was true.  Indeed, many philosophers

in his day used a mathematical method in their philosophizing.  Is it

possible to doubt that, for example, 2+2=4?  I'll let you think this one

through on your own, as an encouragement to read Descartes' book for

yourself.  But suffice it to say that Descartes believed even mathematics

cannot provide an absolutely certain foundation for knowledge.



    What is it then that is impossible to doubt?  As Descartes lay on his

bed in a dark room doing this prolonged thought experiment, he suddenly

hit upon the answer he had been searching for.  He found he could not

doubt that at that moment he was doubting.  For this would be possible

only under the absurd conditions that a doubt could exist without anyone

doing the doubting!  Doubt is a form of thinking, Descartes reasoned in

his second meditation, so thinking must be the basis upon which the

certainty of his own existence could be proved.  Hence he came up with the

now famous maxim, "I think, therefore I am" (in Latin, Cogito ergo sum).

The existence of this "thinking being" is the absolute certainty upon

which all knowledge can be based.  This "I" or "ego" stands outside of

history and culture as a basic metaphysical given, which does not depend

on any kind of faith, since its nonexistence is impossible as long as I

know I am thinking.



    No sooner did Descartes reach this conclusion than he realized that it

presents a problem which requires some solution.  Descartes himself

refused to side with Plato by treating the body as an illusion, for as a

scientist he believed the body is just as real as the mind. Instead he

adopted a metaphysical viewpoint known as "dualism", according to which

the mind and body are both equally real.  Just as the former is a

"thinking substance" (res cogitans), the latter is an "extended substance"

(res extensa).  Yet he had now demonstrated that our knowledge of our

bodies, together with the whole of extended nature, can never be as

certain as our knowledge of our thinking nature.  So on what can such

confidence in the reality of the body be based? And just how is it that

the mind and body are related?



    Descartes answered the first question in his third meditation by

appealing to God. He began by constructing what is now referred to as an

"ontological argument" for the existence of God (i.e., an argument

appealing only to the proper understanding of the concept "God").  His

proof goes something like this:  we all have within us an idea of

"perfection"; no human being is perfect, so the perfect Being is not the

"I" of whose existence I am certain; yet this perfect Being must actually

exist, for otherwise it would be less than perfect (i.e., if our concept

of a most perfect Being refers to a Being who does not really exist, then

that Being would not be as perfect as a perfect Being who does exist).

Descartes then argues that, since we can in this way be certain that a

perfect Being ("God") exists, and since such a Being must be good in order

to be perfect, we can also be confident that such a Being would not

deceive us.  In response to critics who claimed such an argument is

circular, Descartes appealed to the notion of "innate ideas" (ideas that

are present in our mind at birth, and are therefore self-authenticating),

claiming that "God" is an innate idea just as much as is the idea of my

own "ego".



    Even if we accept Descartes' theological explanation for why we can

have confidence in the reality of the external world, the question remains

as to how our minds actually relate to our bodies, if indeed they are two

ultimately distinct substances.  Descartes' solution to this problem never

met with much approval from his fellow philosophers.  He surmised that a

small gland at the base of the brain, called the "pineal gland", is

responsible for ensuring a causal connection between the mind and body.

In Descartes' day the prevailing idea of the human body was that it is a

kind of living machine, so that any time one part moves, it must have been

caused to move by a mechanical process whereby some other part, as it

were, "bumped" into it.  So Descartes claimed that, when the mind wants

the body to do something, it somehow influences the pineal gland, where it

sets off a chain reaction which ends in the desired action being

performed.  So if my mind tells me to throw this piece of chalk up in the

air, that idea, as it were, spins round and round in my mind until it

gathers enough force to make a significant impact, then it bangs into my

pineal gland, sending a series of movements through my neck and down my

arm, until my arm actually obeys the command, like this!



    Having explained Descartes' two main ways of defending his

metaphysical dualism, we can now use the diagram in Figure 6.2 to

summarize his theory:



[Figure 6.2:  Descartes' Dualism]



There are several important consequences of this theory.  For one thing,

Aristotle's definition of man as the "rational animal" is now replaced by

a notion of man as a mind imbedded in a fleshly machine.  In the field of

natural science this had the significant effect of providing scientists

with a world view that enabled them to attain (or at least, to believe

they could attain) a totally objective perspective on the external world,

abstracting completely from any influence from the observer's own mind.

In this sense, Descartes' dualism can be regarded as paving the way for

Newtonian science.  The view that the human ego controls the material

world, though now called into question by many modern thinkers, is what

enabled technology to develop so rapidly over the past three hundred

years.



    But for our purposes the most significant consequence of Descartes'

dualism was that it sparked off a controversy, commonly known as "the

mind-body problem".  Since the mind and body apparently do influence each

other, and since Descartes' own explanation is highly implausible, what

other solution can be found?  The debate over the proper answer to this

question began almost immediately, and is, in fact, still alive in some

philosophical circles today. For example, one of the most influential

books written by an analytic philosopher in this century was Gilbert

Ryle's The Concept of Mind, which begins by arguing that Descartes'

dualism is based on a "category mistake", and that a proper understanding

of the way we use words like "mind" and "body" can resolve the whole

mind-body problem once and for all.



    The mind-body controversy was at its height in the century immediately

after the publication of Descartes' Meditations.  There is, of course, no

time to give an exhaustive account of the many arguments here.  However,

it might be helpful to give a brief summary of five of the most notable

alternatives to Descartes' own solution to the mind-body problem, as

represented in each case by their most influential proponents.  They are

as follows:



    (1) Materialism:  Thomas Hobbes (1588-1679) argued that only matter

truly exists.  The mind is just a special configuration of brain matter.

Therefore there is no problem of interaction, because the whole system is

physical.  This view is similar, though by no means identical, to

Aristotle's realism.



    (2) Immaterialism:  George Berkeley (1685-1753) argued that only

perceptions truly exist.  There is no reason to believe matter has any

independent existence outside of the perceiving mind.  Therefore there is

no problem of interaction, because the whole system is spiritual.  This

view is similar, though by no means identical, to Plato's idealism.



    (3) Parallelism:  Nicolas Malebranche (1638-1715) argued that the mind

and body are indeed separate substances, but they do not actually

interact.  They seem to interact whenever a mind's thoughts and a body's

actions happen to run parallel to each other; but in such cases the

correspondence is governed directly by God.



    (4) Double Aspect theory:  Benedictus de Spinoza (1632-1677) argued

that the mind and body (like all spirit and matter) are two aspects of one

underlying reality, which can be called either "God" or "Nature",

depending on how the subject views it.  Reality is like a coin with two

quite different faces, both of which are equally true as a description of

the coin.



    (5) Epiphenomenalism:  David Hume (1711-1776) argued that the mind is

nothing but a bundle of perceptions arising out of the body.  Later

philosophers refined this idea, arguing that the body is the primary

reality, but it creates out of itself a mind, which then has a reality of

its own.



    I'd like to conclude today's lecture by suggesting one very

significant difference between Descartes' metaphysics and that of Plato

and Aristotle.  For Plato and Aristotle, and for most philosophers over

the next two millennia, the answer to the basic question of epistemology

("What can I know?") was dependent upon a foregoing answer to the basic

question of metaphysics ("What is ultimately real?")  For Descartes,

however, the opposite was true.  As we have seen, he began his enquiries

by asking what we can know for certain, and only on the basis of the

answer to this question did he construct his metaphysical dualism.



    As we shall see in the following lecture, the next major metaphysician

whose ideas we shall be considering also gave priority to epistemology.

Anticipating that lecture just slightly, I would suggest that we can

therefore use the cross as a map of the relationship between the methods

employed by the four metaphysicians considered here in Part One, in the

following way:



[Figure 6.3:  Four Key Philosophical Methods]



    One of the chief dangers for beginning students of philosophy is that

they may be overwhelmed by the great diversity of viewpoints and arguments

which have been expressed on a given subject, such as metaphysics.

Although maps like the one above inevitably over-simplify the complex

relationships between such philosophers, they nevertheless can help us to

get a handle on their basic similarities and differences, as well as

suggesting further insights of various sorts.  For example, this diagram

suggests that the development of western philosophy can be regarded as a

process of slowly working backwards from, as it were, the highest and most

aloof insights, to the deepest groundings of human reasoning.  We shall

see in the next lecture the extent to which this suggestion gives us an

accurate description of the contribution Kant made to the roots of our

philosophical tree.







QUESTIONS FOR FURTHER THOUGHT



1. Is it possible to doubt that 2+2=4?



2. Are you certain of anything?



3. Can the mind exist without a body?



4. What would be the ideal philosophical method?







RECOMMENDED READINGS



1. Rene Descartes, Meditations on First Philosophy2, tr. Laurence J.

Lafleur (New York:  Bobbs-Merrill, 1960[1951]).



2. Gilbert Ryle, The Concept of Mind (New York:  Barnes & Noble, 1949),

especially Chapter I, "Descartes' Myth", pp.13-25.



3. George Berkeley, Principles of Human Knowledge (London:  Collins,

1962).



4. W.H. Walsh, Metaphysics (London:  Hutchinson, 1966).