“Suppose you are Hume.  Suppose that you have been asked to write a six-page essay critically assessing Descartes’ philosophical project as he describes it in the Discourse and Meditations, and his treatment of his own nature, the God question, and human knowledge.  Write it.”

Hello, my name is David Hume.  I’ve recently been asked to write a short essay critiquing some of Rene Descartes’ ideas and presenting my own ideas in contrast, and this essay is the result.  Our ideas differ quite a bit, and I hope to convince you in this essay that Descartes doesn’t have all the “answers,” and that without empirical evidence all of his theories are just that—theories—and nothing more.

Rene Descartes, simply put, believes he’s right—about everything.  He truly believes that by starting literally “from scratch” (as he puts it, “I rejected as false all the reasonings that I had previously taken for demonstrations” (Discourse 18)) he can discover who and what he is—human nature—as well as everything about God, the laws of nature, and virtually everything else…in short, life, the universe, and everything.

His first step is to prove that he himself exists.  His simple argument: “I think, therefore I am.” (Discourse 18)  Soon after, he shows a belief in the substance of man—that our “soul,” the part of us that thinks and interprets information, is a separate entity from our corporeal bodies.

First of all, I emphatically disagree with the notion that all of the universe can be explained by philosophy—Descartes can postulate and conjecture all he wants, but there will always be things that will be beyond our comprehension.  As I’ve stated in my writings, “All the objects of human reason or inquiry may naturally be divided into two kinds, to wit, Relations of Ideas, and Matters of Fact.” (Packet 59)  Thus, Descartes is flawed in believing he can explain everything by starting at nothing because he cannot start at nothing—if he throws out all his relations ideas and matters of fact that he has discovered or experienced throughout his life, he would be unable to reason effectively.  Cutting down the weed by the roots:  Proclaiming “I think, therefore I am” solely on the grounds that he knows he’s thinking can’t stand because if he truly is starting at zero, he doesn’t know what thinking is.

Now, onto Descartes’ assertion that the mind is separate from the body: Descartes claims that “in order to exist, one has no need of any place nor depends on any material thing” (Discourse 19).  To this I say, “Prove it!”  Is there anyone out there existing without a body?  Descartes claims that the soul is neither born nor destroyed along with the body, but can he remember anything of the period before he was born?  Has his (or any other) spirit come back to the world after the death of its body to show that the soul is, indeed, immortal?  Of course not, or at the very least no instances of such events have occurred that have proved to be more than a hoax or urban legend.   With regards to this notion of the transplantation of the soul, “Judging by the usual analogy of nature, no form can continue, when transferred to a condition of life very different from the original one, in which it was placed.”  (Packet 95)  Why then, should we assume the same shouldn’t be true for the soul, if there is such a thing as a soul at all?

Myself, I believe that the “self” Descartes perceived to be a soul is simply the bundle or aggregate of experiences one has acquired since birth.    This establishes our personal identity—my sum total of experiences is different from the readers, and thus we have different thought processes and can come to different conclusions on the same matters.  As I succinctly state in my Treatise of Human Nature, “the objects in the bundle, which are variable or interrupted, and yet are suppos’d to continue the same, are such only as consist of a succession of parts, connected together by resemblance, contiguity, or causation.” (Packet 81)  Consciousness can thus simply be thought of as the “theatre” upon which our experiences and passions collide.  We therefore conclude that “the identity, which we ascribe to the mind of a man is only a fictitious one, and of a like kind with that which we ascribe to vegetables and animal bodies.  It cannot, therefore, have a different origin, but must proceed from a like operation of the imagination upon like objects.” (Packet 83)  I do admit that there is a line where the brain ends and consciousness (or soul, for that matter) begins, but as I say in Of the Immortality of the Soul, “Matter, therefore, and spirit, are at bottom equally unknown, and we cannot determine what qualities may inhere in the one or the other.” (Packet 93)

Returning to Descartes’ arguments, he next attempts to prove that there is a supreme being—God.  He uses three separate arguments (ideotheological, egological, ontotheological) to do this.  For the sake of brevity, I shall just restate the ideotheological argument here: We have the concept of God, and it’s impossible that we came up with the idea ourselves.  As Descartes states, “I decided to search for the source from which I had learned to think of something more perfect than I was, and I plainly knew that this had to be from some nature that was in fact more perfect.” (Discourse 19)

Consider the definition of a circle: the set of points equidistant from a single point in space.  We can conceive of a perfect circle in our minds simply by closing our eyes and imagining it.  However, no such circle exists in the world!  Any circle drawn by a man will have its flaws, no matter how steady the hand.  The paper the circle is drawn on has its flaws as well, with microscopic bumps and ridges to further contaminate our perfect circle.  The pen or stylus with which the circle was drawn also has its own defects.  A clever sort might argue that a computer can display a perfect circle on the screen, but, alas, even a computer is limited by the resolution of the monitor—if we were to examine a computerized circle on a pixel level, we would see that the circle has rough edges caused by a series of finite points (pixels, in this case) being necessarily unable to produce a perfect curved line.  Only a computer monitor with infinite pixels would be able to depict a true perfect circle, not to mention the infinite processing time needed to render such an object.  Both infinities are impossible in our universe—or at the very least, well beyond the capacity of anything that has existed or currently exists to create.

Now comes the philosophical part of the argument: Descartes freely admits that man is an imperfect being.  Man errs, man stumbles, and man makes mistakes.  How, then, is man able to conceive of a perfect circle?  No man has ever seen one, drawn one, or stumbled upon one in any place other than in his or her own mind.

Descartes argues that man could not conceive of perfection unless there was such a thing.  Since man is flawed, this means that there must be something more perfect than man in order to place the notion of perfection into man’s mind.

Another clever sort might point out that perhaps an entity more perfect than man exists, but that this being is not all perfect. By the same logic he used earlier, Descartes postulates that some being more perfect than that less-flawed-but-still-flawed being would need to exist to put the idea of total perfection into its mind, and by recursively repeating that idea, Descartes arrives at the hypothesis that there must therefore be a supreme, perfect being: God.

Responding to this ideotheological argument for God…chipping away first at the claim that God must be utterly perfect (merely the thought that this was not so would reduce Descartes to confusion, as he states himself when theorizing that God might not be omnibenevolent: “…as if I had suddenly fallen into a deep whirlpool, I am so disturbed that I can neither touch my foot to the bottom nor swim up to the top.” (Note Packet, 54)), I wonder first how God could possibly be omnibenevolent after seeing all the horrors and atrocities of the world we occupy!  After all, “we must acknowledge the reality of that evil and disorder with which the world so much abounds.” (Packet 70)  Descartes asserts that God must be all-powerful and all-intelligent simply because we have notions of such things, and to this I reply that assuming that God did in fact create the universe, and basing our conclusions as to what God must be like solely on the product of God’s work (the universe), “it follows that they possess that precise degree of power, intelligence, and benevolence which appears in their workmanship, but nothing further can ever be proved, except we call in the assistance of exaggeration and flattery to supply the defects of argument and reasoning.” (Packet 69)  And, since God has never shown up to provide empirical proof of his existence, that’s the best we can do—“The experienced train of events is the great standard by which we all regulate our conduct.  Nothing else can be appealed to in the field or in the senate.” (Packet 71)

Once Descartes has sufficiently proven (in his opinion) God to exist, he basically skims over the rest of his proofs for the laws of nature—basically, how and why the universe works in the fashion it does—by saying that those laws are what they are simply because God wanted an ordered universe and made it that way: “Moreover, I showed what the laws of nature were, and, without supporting my reasons on any other principle but the infinite perfections of God, I tried to demonstrate that concerning all those laws…even if God had created many worlds, there could not be any of them in which these laws failed to be observed.”  (Discourse, 24)

The main problem I see with this argument is that an imperfect God could have created our universe, and thus created the laws of nature as well.  As I stated previously when discussing God’s omnipotence, assuming that God is perfect rather than just supremely powerful simply for creating the universe is imagining a cause that is bigger than the effect, when the two must be irrevocably intertwined: “The knowledge of the cause being derived solely from the effect, they must be exactly adjusted to each other, and the one can never refer to anything further or be the foundation of any new inference and conclusion.” (Packet 69)  Thus, the only thing we can absolutely ascribe to God for creating the universe (assuming he did such a thing) is that he has just enough power to do exactly that, and not a drop more.  He might be omnipotent and all the other things that Descartes claims, but, again, “nothing further can ever be proved.” (Packet 69)

Things are meaningful to us only as insofar as we can point out experiences that give them meaning and content.  While Rene Descartes has some beautiful theories about human nature and the existence of a supreme being, he has little empirical proof to back him up.  While I cannot conclusively disprove Descartes’ philosophical theories themselves (after all, I can no more prove a negative to be true than Descartes could—especially in the field of philosophy, where full answers are few and far between), the reasonings he uses to explain those theories are suspect.  To paraphrase a famous saying of mine, do Descartes’ proofs contain any abstract reasoning concerning quantity or number?  No.  Do they contain any experimental reasoning concerning matter of fact and existence?  No.  Commit it then to the flames: For it can contain nothing but sophistry and illusion.  (Packet 65)


Descartes, Rene. (ed. Cress, Donald)  Discourse on Method and Meditations on First Philosophy.  Indianapolis: Hackett Publishing Company, 1998.

Philosophy 101 Note Packet (Schacht).  University of Illinois, Fall Semester 2000.

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