Reality Consists of Mind and Matter
Classic Philosophical Questions Part 6 - Metaphysics
René Descartes, from the Meditations
Kem Stone - 16 January 2008
One of the most fascinating questions in all of philosophy is the mind-body problem, or more fundamentally: of
what does reality ultimately consist?  In our experience, we are presented both with a world of corporeal objects
and an awareness of that world, the latter of which seems to have no substance at all and yet is the only thing we
can be certain exists.  It is Descartes who showed us that mind
must exist, and further in his Meditations he
argues for the metaphysical position of substance dualism, insisting that reality consists of two basic entities: mind
and matter.  Though I believe that dualism is actually the most plausible of all metaphysical theories, I do not
believe Descartes’ arguments in this case are very strong.

He begins by stating the facts—what he has observed in his experience.  This includes the fact that he has a body,
that this body is placed among many others which are capable of affecting it in different ways, that feelings of
pleasure or pain accompany the effects of other bodies depending on whether they are helpful or harmful, that
certain appetites such as hunger and thirst are frequently experienced as well as joy, sadness, and anger.  In other
bodies he has observed the properties of extension, figure, and motion as well as certain tactile qualities including
hardness and heat, and even more dubious qualities such as light and colour, scents and sounds.

From what he is given, Descartes adds the proposition that what he experiences through the senses is much
clearer than what he perceives in his imagination, and leaps to the conclusion that the objects of his perception
therefore must exist in reality.  “I could not perceive any object, however desirous I might be, unless it were
present to the organs of sense; and it was not in my power not to perceive it, when it was present.  And because
the ideas which I received through the senses were much more lively, more clear, and even, in their own way,
more distinct than any of those which I could of myself frame in meditation, or than those I found impressed on my
memory, it appeared as though they could not have proceeded from my mind, so that they must necessarily have
been produced in me by some other things” (352).

After hastily concluding that corporeal objects could not have arisen from his own mind, Descartes goes on to
prove a distinction between these objects and the mind that perceives them, a far more persuasive portion of his
argument.  He first concludes based on the fact that all of his ideas are actually composed of previously received
sensations, that there is no idea in the mind that has not come through the senses.  He then brings in the
proposition that he came to conclude earlier in his Meditations, that the only necessary quality of his existence is
thought, and that therefore his essence lies solely in the fact that he is a thinking thing.  Having now established that
all of his ideas come to him through his senses, and that these senses are a part of a body to which he is intimately
conjoined, because this body is an extended and unthinking this while he is essentially an un-extended and thinking
thing, he must be absolutely distinct from his body and separate from it.

Having established an absolute distinction between mind and matter, Descartes then turns around and offers
another argument for why corporeal objects must exist which is even weaker than the first.  He begins by drawing
another distinction between mind and matter: that he can conceive of himself as a complete being without certain
mental faculties such as imagination and feeling, but he cannot conceive of these mental faculties existing without an
intelligent substance doing the imagining or feeling.  On the other hand, he cannot conceive of corporeal objects
without certain of their faculties such as figure and motion just as he cannot conceive of figure and motion without
the objects they pertain to.  If these faculties exist, they must be attached to something other than an intelligent

The problem then is how do perceptions of corporeal things come into his mind if they do not exist?  “There is
certainly further in me a certain passive faculty of perception, that is, of receiving and recognising the ideas of
sensible things, but this would be useless to me…if there were not either in me or in some other thing another
active faculty capable of forming and producing these ideas.  But this active faculty cannot exist in me…seeing that
it does not presuppose thought, and also that those ideas are often produced in me without my contributing in any
way to the same, and often even against my will” (353).  This other thing that is responsible for the perception of
objects, Descartes concludes, is either a body of corporeal nature or else God Himself, the latter hypothesis being
the idea that Berkeley would come to adopt.

So far, Descartes’ argument is strong, and it would seem as though our perceptions must either come from one of
these two sources.  Either we perceive objects because our minds have an active faculty of perception upon
which the power of these objects impresses representations of themselves onto our minds, in which case we have
dualism and a world that really exists.  Or we have God or some divine entity that through a power of thought far
superior to our own, holds all of these ideas of reality in place and provides our awareness directly with ideas of
these objects, in which case reality consists of
ideas only and there is no material world.  Descartes must only
show why the latter option cannot be the case, and he will have proven the existence of material reality!  
Unfortunately, the argument rests on the totally unfounded premises that God is not a deceiver, and that all of his
clear and distinct ideas come from God.  “Since He has given me…a very great inclination to believe…that they
are conveyed to me by corporeal objects, I do not see how He could be defended from the accusation of deceit if
these ideas were produced by causes other than corporeal objects.  Hence we must allow that corporeal things
exist” (354).  Descartes’ justification can be reduced to nothing more than a very strong feeling that his opinion is
the truth, and it therefore has no real justification at all.

The possible objection he responds to is not the one I would level at him—that he can not prove that God is not a
deceiver or that all of his clear and distinct ideas come from God—but rather that some of his ideas which are not
so clear and distinct are subject to doubt because of their dubious nature.  Things like light and sound, which were
not so well understood in Descartes’ time, might be presented as evidence that not all of his ideas are clear and
distinct and that therefore he can not be certain he is not mistaken regarding their existence as properties within
corporeal things.  Yet Descartes once again appeals to the sole premise that God is not a deceiver, and that
although he lacks as much knowledge regarding these qualities as he does to those more concrete qualities such as
extension and figure, he can still at least hope to arrive at the truth.  “And first of all there is no doubt that in all
things which nature teaches me there is some truth contained; for by nature, considered in general, I now
understand no other thing than either God Himself or else the order and disposition which God has established in
created things; and by my nature in particular I understand no other thing than the complexus of all the things
which God has given me” (354).  By Descartes’ reasoning, both mind and matter exist, both come from God, and
the distinct idea of a direct connection between mind and matter proves that this connection exists, and rules out
the possibility that matter does not exist and that all such ideas are placed directly in the mind by God.

The remainder of the text consists not of arguments, but of statements concerning the nature of metaphysical
reality as Descartes imagines it, specifically in regards to the connection between mind and body.  He returns to
one of the facts presented at the beginning of the text—that he experiences hunger, pain, and thirst in a very direct
way—and that this is evidence that the mind does not control the body as though lodged in a vessel, but that mind
and body together compose one whole.  He could perceive pain as a captain in a ship would perceive a hull
breach, disconnected yet aware of it, but this is not the case.  “For all these sensations of hunger, thirst, pain, etc.
are in truth none other than certain confused modes of thought which are produced by the union and apparent
intermingling of mind and body” (354).

Having given more support to the idea that mind and body are intertwined, Descartes then offers another
distinction to separate them.  The body, by nature, is always divisible, while the mind is entirely indivisible.  When
considering the “I” it is always perceived as a singular entity, without distinguishable parts.  The body, on the other
hand, can easily be divided into parts.  This in itself, Descartes suggests, would be sufficient argument that mind
and body are separate entities.

Further support for this idea lies in physics, when we consider that “the mind does not receive the impressions
from all parts of the body immediately, but only from the brain, or perhaps even from one of its smallest parts, to
wit, from that in which common sense is said to reside” (355).  From the fact that a sensation of a pain in the foot
must be communicated by the nerves in the foot through the body and into the brain for interpretation, Descartes
concludes that the mind and body are separate, but here we have the much more interesting (and objectionable)
idea that the mind and
brain are separate as well.  Descartes does not identify the mind with the brain, which he
sees as just another organ of the body, but of a small part of the brain in which common sense is said to reside.

Descartes concludes by switching gears from a metaphysical argument to a teleological argument, foreshadowing
Paley by using the mind-body connection as evidence of design by an omnipotent, benevolent God.  The fact that
the mind receives impressions such as pain and thirst as direct sensations, and not merely through the
understanding, is a far better scheme for the conservation of a healthy body.  When considering a wound in the
foot, we are far more likely to attend to the wound if we experience it as a direct sensation of pain, than merely by
understanding that our foot is wounded and must be tended to.  “Similarly, when we desire to drink, a certain
dryness of the throat is produced which moves its nerves, and by their means the internal portions of the brain;
and this movement causes in the mind the sensation of thirst, because in this case there is nothing more useful to us
than to become aware that we have need to drink for the conservation of our health” (356).

Curiously, Descartes then weakens his own argument by admitting that the nature of the connection between mind
and body may sometimes be a source of deception.  He may be defending against the possible objection that if a
perfect God really is the designer of this system, why might we experience a pain in the foot when at times the
wound is elsewhere?  Why might we experience parchedness of the throat when we are in fact not in need of
drink, as might be the case when we have taken certain medicines?  Descartes’ answer is that God is not to blame
for these imperfections but it is simply the nature of man which allows for certain confusion among the nerves
which may indicate a pain where there is no wound, or a parchedness of throat when there is no thirst.  Yet it is
far better to be occasionally deceived by false pain or thirst than to be always deceived by our sensations.  The
question of why a perfect God would even admit of the possibility of such obvious flaws is not addressed by

Before offering my objections to Descartes’ main arguments, I should say that I find dualism to be the most
persuasive metaphysical scheme in philosophy.  Though Descartes’ defence of this position is extremely weak, he
points to the reason why it is the most logical with his argument that “I am a thinking substance while my body is
not” and thus that these two phenomena are separate and distinguishable.  The phenomenon of awareness, I
believe, is so far removed from the phenomenon of a body and the world of corporeal objects that a separation
between the two seems much more reasonable than the idea that one arises from the other.  I completely reject
the view that thought arises from matter, as it seems absurd that unthinking substance can somehow give rise to
the property of awareness where no such thing existed before.  Yet the opposite view is not as easily dismissed.  
Berkeley’s claim that reality consists only of mind and that matter arises from the mind of God is, I think, much
more plausible, and this is the idea that Descartes fails to defeat.

Descartes’ first argument for the existence of corporeal objects is that the sensations we receive from them are
much more lively and clear than the idea of corporeal objects that we can conjure with our imagination.  But
qualities such as “lively” and “clear” do not constitute any sort of proof for actual existence.  The un-stated
premise here is that “If
x is lively and clear, x exists as a corporeal object.”  Any number of examples can be
given to prove this false, the most obvious being that of dreams.  In my dreams I am often presented with images
that I would certainly describe as lively and clear, even vivid and detailed, and yet almost nobody would deny that
the source of such images
is the mind and not the sensation of actual objects.  Contemporary neuroscience even
tells us that the same activity takes place in the brain whether one is experiencing something in the real world or in
a dream.

Descartes’ second argument is even weaker than the first: that he has a clear and distinct idea that he receives his
impressions from corporeal objects and not directly from God, and since God is the source of his clear and
distinct ideas and God is no deceiver, this assumption
must be correct and corporeal objects must exist.  It is one
thing to have faith in the existence of God, but to have faith that any clear and distinct idea must be correct
because it comes from God is not nearly as defensible.  Not only must you grant that God exists and that He is the
source of all your clear and distinct ideas, but you must also trust the highly dubious claim that God can not
deceive.  Descartes does not give any reasons in this particular text as to why he believes that God can not be a
deceiver, but elsewhere he argues that deception is inherently evil, and since God is incapable of evil, He is
therefore incapable of deception.  Even if we overlook the gross logical error of claiming that an omnipotent being
incapable of anything, we are still left with the objectionable idea that deception is inherently evil.  Deception
itself is neither good nor evil—it is how deception is
used that renders it ethically sound or not.  Should deception
be used to start a war, it can be said to be evil.  Should it be used to prevent a war, in this case it is good.  So we
have here an argument for the existence of corporeal objects in which
every premise is extremely dubious and
uncertain, and so Descartes fails to prove dualism.

Finally, moving from Descartes’ metaphysical argument to the teleological claim that the mind-body connection
has been designed in the best possible way for the conservation of human health and therefore by God, anyone
familiar with contemporary biology knows the flaw in this reasoning.  To be fair, Descartes lived before Darwin,
and thus was never forced to consider that natural selection, and not an intelligent designer, could be responsible
for the configuration of the mind-body connection.  Towards the very beginning of the evolutionary process, any
creature which did not experience pain, hunger, or thirst directly yet merely through the understanding would be
far less likely to care for itself and thus live long enough to pass on its genes to the next generation.

In spite of the many flaws in his arguments, I would still credit Descartes with taking the correct metaphysical
position through the basic understanding that mind and body must be separate entities.  His argument for the
existence of mind, “I think, therefore I am,” is ingenious and holds up quite well even to this day.  Yet his
arguments for the existence of bodies fall tragically short of any real persuasiveness.  But in Descartes’ defence,
our current understanding of God, the brain, and the nature of good and evil is much different than the time in
which he lived, and had he existed today he may have come to very different conclusions.  Also, one cannot call
the failure to prove the existence of the material world much of a shortcoming, as no philosopher who has ever
lived, and probably no philosopher who will ever come, can prove such a thing.  To prove to the understanding
the concrete, actual existence of
anything (other than the understanding itself) is probably an impossible task, and
Descartes’ failure to do so is like failing to reach the moon by trying to jump high enough.