RENE DESCART'BS
286
The second reading, by Anne Conway, takes the view that mind and body are not
radically distinct things as Descartes believed. Instead, there is a graded progression
from heavy body to light body to heavy spirit to light spirit, where each level impacts
those next to it. Thus, light spirit communicates with heavy body through this continuum.
Next, we look at a contemporary overview on the problem of dualism and materialism by Jerome Shaffer. In'our fourth ¡eading, Paul Churchland critiques this position.
Then, in our fifth reading, Churchland critiques functionalism and defefids materialism,
especially elíminative materialism,whichattempts to eliminate all talk of mental states
and claims that the language of mental events is an outmoded legacy of folk mythology, calledfolk psychology, which includes our concepts of belief, pain, desire, emotion andintention. As we learn firore about our brains and how they work, Churchland
argues, we will be able to replace this subjectivist language with more scientific
discourse.
Our sixth reading, Thomas Nagel's "What Is It Like to Be a Bat?" is a critique of
this kind of objectivism, the view that we can give a complete and accurate description
of the world by omitting the subjective point of view. Nagel argues that subjectivity, conscious awareness, is an integral part of both our experience and the world itself. In our
sixth reading David Chalmers argues in favor of naturalistic dualism and against reductive materialism.
Finally, we turn to the question of whether computers can think. The British genius
A. N. Tirring proposed a test, now called the Turing test, in which a sophisticated questioner could not tell the difference between the answers of a computer and a hlrman being.
In our final selection, "Minds, Brains, and Computers," John Searle uses a thought experiment called the "Chinese room" to argue that while it may be possible for a computer
to fool a sophisticated questioner, the computer will lack something a human possessesnamely, understanding of themeanings of the symbols that are being manipulated. Since
what we mean by thinking involves interpretation of symbols and understa¡dding, the computer, unlike us, cannot
think.
r
u
t'
RENÉ DeSCARTES
râ
INTERACTIVE DUALISM
French philosopher René Descartes (1596-1650) is perhaps the leading defender of the
position known as interoctiueå,ualístn.In this view, my body is composed of physical stuff, while
my mind is a nonphysical spiritual entity. While metaphysically distinct entities, my spirit'
mind and physical body nonetheless interact with each other. My body sends sensory information to my mind, and my mind issues commands to my body that make it move. Descartes
INTERACTIVE DUALISM
287
lays out hi, porition in two works, selections from which are presented here. First, in his
Discourse ontheMethoà (1631), he describes his mental self as a thinking thing that is distinct
from-and can even exist apart from-his physical body. He then describes the functioning
of the body as a machine that is guided by the mind. In the process of describing the relationships between mind and body, he argues that animals are mere machines. Second, inThe
Passíowsof thesout (1.649),Descartes argues that the interactive gateway between these realms
of the spirit-mind and physical body is the pineal gland in the brain.
_-
THE MIND DISTINCT
FROM THE BODY
The Mínd. Is
a
I am, was so cèrtain and of such
ground
of doubt, however extravaevidence, that no
gant, could be maintained by the skeptics capable of
shaking it. I concluded that I might, without scruple,
accept it as the first principle of the philosophy of
which I was in search.
In the next place, I attentively examined what I
was. I observed that I could suppose that I had no
body, and that there was no world, nor any place in
which I might be. But I could not therefore suppose
that I was not. On the contrary, from the very circurnstance that I thought to doubt the truth of other
things, it most clearly and certainly followed that I
was. On the otherhand, if I had only ceased to think,
although all the other objects which I had ever
imagined had been in reality existent, I would have
had no reason to believe that I existed. I concluded
from this that was a substance whose whole
essence or nature consists only in thinking, and
which, that it may exist, haS need of no place, nor
is dependent on any material thing. Thus the "I"
(that is to say, the mind by which I am what I am)
is wholly distinct from the body. It is even more
easily known than the [body], and is such that even
I
Think íngThíng Dístinct
fromtheBod.y
I had long before remarked that from practical considerations it is sometimes necessary to adopt almost
beyond\ubt opinions that we observe to be highly
uncertain. But as I then desired to give my attention
solely to the search after truth, I thought that a procedure exactly the opposite was needed. I ought to
reject as absolutely false all opinions in regard to
which I còuld suppose the least ground for doubt, in
order to ascertain whether after that there remained
[anything] in my belief that was wholly indubitable.
Accordingly, seeing that our senses sometimes
deceive us, I was willing to suppose that there existed
nothing really such as they presented to us. And
because some people err in reasoning, . . . even on the
simplest matters of geometry, I, convinced that I was
as open to error as any other, rejected as false all the
reasonings that I had before taken for demonstrations. Finally, when I considered that the very same
thoughts that we experience when awake may also be
experienced when we are asleep, while there is at
that time not one of them true, I supposed that all the
objects that had ever entered into my mind when
awake, had in them no more truth than the illusions
of my dreams. But immediately I observed that,
while I thus wished to think that everything was false,
it was absolutely necessary that I, who thus thought,
should to some extent exist. I observed that this truth,
From René Descartes, Discourse on the Method (1637), Part
been added by the editor.
think, thereþre
I
if the lbody] did not exist, lmy mind] would still
continue to be all that it is.
T
he
M e chaní cal N øtur
e
of th e B o å.y
I had expounded all these maffers with sufficient detail
in the treatise which I formerþ thought of publishing.
And after these, I had shown what must be the fabric
of the nerves and muscles of the human body to give
4,
and
The Passions of the Soul (1649), Part 1. Section titles have
288
the animal spirits contained in it ttre power to move the
limbs. We see this, for example, when heads shortly
after they have been cut off still move and bite the
earth, although no longer animated. [We also see this]
in the changes that must take place in the brain to produce waking, sleep, and dreams. [Wg also see this]
with how light, sounds, odors, tastes, heat, and all the
other qualities of external objects impress it with different ideas by means of the senses, and similarly
with how hunger, thirst, and the other internal passions can likewise impress upon it divers ideas. [We
also see thisl in what must be understood by the
"common sense" in which these ideas are received by
the memory which retains them, by the imagination
which can change them in various ways and out of
them compose new ideas, and which, by the same
means, distributing the animal spirits through the
muscles, can cause the members of such a body to
move in as many different ways, and in a manner as
suited, whether to the objects that are presented to its
senses or to its internal passions, as can take place in
our own case apart from the guidance of the will.
Nor will this appear at all strange to those who are
acquainted with the variety of movements performed
by the different automata, or moving machines created by human engineering, and that with help of but
few pieces compared with the great multitude of
bones, muscles, nerves, arteries, veins, and other parts
that are found in the body of each animal. Such persons will look upon this bõdy as a machine made by
the hands of God, which is incomparably better
arranged, and adequate to movements more admirable
than is any machine of human invention. And here I
especially stopped to show that, were there such
machines exactly resembling in organs and outward
form an ape or any other irrational animal, we could
have no means of knowing that they were in any
respect of a different nature from these animals.
On the other hand, if there were machines resembling ourbodies, and capable of imitating our actions
as far as it is morally possible, there would still remain
two most certain tests whereby to know that they were
not really human. Of these the first is that they could
never use words or other signs arranged in such a
manner as is competent to us in order to declare our
thoughts to others. For, we may easily conceive a
RENÉ DESCARTES
machine to be so constructed that it utters words, and
even that it utters somÞ in response to the action upon
it of external objects which causd a change in its
organs. For example, if touched in a particular place
it may ask what we wish to say to it. If touched in
another it may cry out that it is hurt, and such like. But
it would not arrange them variously so as to reply
appropriately to what is said in its presence, as people
of the lowest level of intellect can do. The second test
is that, although such machines might execute many
things with equal or perhaps greater perfection than
any of us, they would, without doubt, fail in certain
others from which it could be discovered that they did
not act from knowledge, but solely from the construction of their organs. For, while reason is a universal
instrument that is available for every contingency,
these organs, on the contrary, need
a
particular
affangement for each particular action. Accordingly, it
must be morally impossible that there should exist in
any machine a diversity of organs sufflcient to enable
it to act in all the occurrences of life, in the way in
which our reason enables us to act.
Anima.I s Høv e Bo d,í es wt th N o Minds or Reason
Again, by means of these trvvo tests wetmay likewise
know the difference between humans\and animals.
For it is highly noteworthy that there are no people so
dull and stupid, not even idiots, as to be incapable of
joining together different words, and thereby constructing a declaration by which to make their
thoughts understood; and that on the other hand, there
is no other animal, however perfect or happily circumstanced, which can do the like. Nor does this
inability arise from the lack of organs: for we observe
that magpies and parrots can utter words like ourselves, and are yet unable to speak as we do, that is,
so as to show that they understand what they say. Yet
there are people who are born deaf and dumb (and
thus not less, but rather more than the brutes) and
thus destitute of the organs which others use in speaking. Yet, they are in the habit of spontaneously inventing certain signs by which they express their thoughts
to those who, being usually in their company, have
time to learn their laiiguage. And this proves not only
that animals have less reason than humans, but that
289
INTERACTIVE DUALISM
they have none at all. For we see that very little is
required to enable a person to speak. And since a certain inequality of capacity is observable among animals of the same species, as well as among people,
and since some are more capable of being instructed
than others, it is incredible that the most perfect ape
or parrot of its species, should not in this be equal to
the most stupid infant of its kind, or at least to one that
was partly insane, unless the soul of animals were of
a nature wholly different from ours.
V/e should alsg not confuse speech with the natural
movements that display the passions, and can be imitated by machines as well as manifested by animals.
Nor must it be thought, as some ancient writers did,
that animals speak although we /o not understand
thdir hnguage. For if such were the case, since they
are en{owed with many organs analogous to ours,
thqy þould as easily communicate their thoughts to us
\their fellows. It is also very worthy of remark
as to
that, though there are many animals that display more
skill than we do in certain of their actions, the same
animals are yet observed to show none at all in many
other actions. Thus, just because they do better than
we do,.this does not prove that they are possessed with
minds. For it would then follow that they possessed
greatet reason than any of us, and could surpass us in
all things. On the contrary: it rather proves that they
are destitute of reason, and that it is nature which acts
in them according to the disposition of their organs.
Thus it is seen that aclock composed only of wheels
and weights can number the hours and measure time
more exactlj'than we with all our skill.
After this I described the rational soul, and showed
that it could by no means be deduced from the power
of matter, as the other things of which I had spoken.
Instead, it must be expressly created. Further, it is not
sufficient for it to be todged in the human body
exactly like a pilot in a ship, unless perhaps to move
its members; rather, it is necessary for it to be joined
and united more clos.ely to the body, in order to have
sensations and appedtes similar to ours, and thus constitute a real person.
In conclusion, I have elaborated on the sgbject of
the soul since it is a topic of considerable importance.
For after the error of those who deny the existence of
God (an error which I think I have already sufficiently
refuted), there is none that is more powerful in leading
feeble minds astray from the straight path of virtue
than the supposition that the soul of the brutes is of the
same nature as our own (and, consequently, that after
this life we have nothing to hope for or fear any more
than flies and ants). Instead, when we know how far
animals differ from us, we much better understand the
reasons which establish that the soul is of a nature
entirely independent of the body, and that consequently it is not liable to die with the latter. Finally,
because we observe no other causes that are capable
of destroying the soul, we are naturally led to judge
that it is immortal.
MIND AND BODY CONNECTED
IN THE BRAIN
31. That there is a small gland ìn the brain in
which the soul exercises its function more'particuIarly than in the other parts. It is likewise necessary
to know that although the soul is joined to the whole
body, there is yet in that a certain part in which it
exercises its functions more particularly than in all
the others. And it is usually believed that this part is
the brain, or possibly the heart. It is believed to be the
brain because it is with it that the organs of sense are
connected. And it is believed to be the heart because
it is apparently in it that we experience the passions.
But, in examining the matter with cate, it seems as
though I had clearly ascefained that the part of the
body in which the soul exercises its functions immediately is in nowise the heart, nor the whole of the
brain. Instead, it is merely the most inward of all its
parts, namely, a certain very small gland which is situated in the middle of its substance and so suspended
above the duct whereby the animal spirits in its anterior
cavities have communication with those in the posterior. It is such that the slightest movements which
take place in it may alter very greatly the course of
these spirits. And, reciprocally, the smallest changes
which occur in the course of the spirits may do much
to change the movements of this gland.
32. How we know that this gland is the mnin seat
of the soul.The reason which persuades me that the
soul cannot have any other seat in all the body than this
RENE DESCARTES
290
gland wherein to exercise its functions immediately, is
that I reflect that the other parts of our brain are all of
them double, just as we have two eyes two hands,
two ears, and finally all the organs of our outside
senses are double. And inasmuch as we have but one
solitary and simple thought of one particular thing at
one and the same moment, it must necessarily be the
case that there must somewhere be a place where the
two images which come to us by the two eyes, where
the two other impressions which proceed from a
single object by means of the double organs of the
other senses, can unite before arriving at the soul, in
order that they may not represent to it two objects
instead of one. And it is easy to see how these images
or other impressions might unite in this gland by the
intermission of the spirits which fill the cavities of the
brain. But there is no other place in the body where
they can be thus united unless they are so in this
gland.
34. How the soul and the body act on one another.
Let us then conceive here that the soul has its principal seat in the little gland which exists in the middle
pf
it
radiates forth
through all the remainder of the body by means of the
animal spirits, nerves, and even the blood, which, participating in the impressions of the spirits, can caÍry
them by the arteries into all the members. Recall what
has been said above about the machine of our body,
that is, that the little filaments of our nerves are so
distributed in all its parts, that on the occasion of the
diverse movements which are there excited by sensible objects, they open in different ways the pores of
the brain. This, in turn, causes the animal spirit contained in these cavities to enter in different ways into
the muscles, by which means they can move the members in all the different ways in which they are capable of being moved. And also, recall all the other
causes which are capable of moving the spirits in different ways and which suffice to conduct them into
different muscles. Let us here add that the small gland
which is the main seat of the soul is so suspended
between the cavities which contain the spirits"tþat it
the brain. For, from this spot
can be moved by them in as many different ways as
there are sensible differences in the object. Further, it
may also be moved in different ways by the soul,
whose nature is such that it receives in itself as many
different impressions, that is to say, that it possesses
as many different perceptions as there are different
movements in this gland. Reciprocally, likewise, the
machine of the body is so formed that from the simple
fact that this gland is differently moved by the soul (or
by such other cause, whatever it is) it thrusts the spirits which surround it towards the pores of the brain,
which conduct them by the nerves into the muscles,
by which means it causes them to move the limbs.
FOR FURTHER REFLECTION
argues that our minds are nonphysical spirits, since I can imagine existing without
1. Descartes
body, but I cannot imagine that I do not think.
Leibniz criticized Descartes as follows: "Someone who thinks that the soul is corporeal . . . will
admit that you can doubt (as long as you are
ignorant of the nature"of the soul) whether anything corporeal exists or does not exist. And as
you nevertheless see clearly that your soul
exists, he will admit that this one thing follows:
that you can still doubt whether the soul is corporeal. But no amount of torture can extort any'What is
thing more from this argument."
a
Leibniz's point, and is he correct?
2. What is Descartes' argument for why even
sophisticated machines will never have the
capacity to reason? Do you agree?
3. What is Descartes' argument for why animals
are incapable of reasoning and have no soul?
Do you agree?
4. Explain why Descartes
says the pineal gland
in
the center of the brain is the gateway between
our physical bodies and mental spirits. Is there
a problem with his theory?