Descarte

Descarte -“I think, therefore I exist”

Descarte persuades himself "that there is nothing in the world" by self-examining what he can and cannot doubt. He does this by investigating three principles of belief. First, he inquires if he can trust all the evidence of his senses.

The conclusion is of course an obvious no as the following example demonstrates: suppose one sees a small brown thing on a wall from some distance and concludes that it is a stain, where in fact upon closer inspection it turns out to be a dormant spider. In this case the individual's senses deceived him into thinking it was a stain rather than a spider; if our senses deceived us even once how can we be certain it has not deceived us before? Therefore by this one counterexample, Descarte argues that we can doubt all our senses. That is not to say that all our senses are false, rather, we have sufficient reasoning to be able to doubt them all.

The following objection can then be raised: we can still trust most of our senses, except those of small and distant objects, surely the existence of tables, trees, and persons cannot be doubted.

Descarte considers the objection by posing it as a weaker principle of belief, namely, can one trust all the evidence except those concerning small and distant objects? Descarte is still able to cast this belief into doubt by arguing for dream skepticism. Descarte argues that one can never be sure if one is dreaming or awake. It then follows that if one perceives objects such as tables, trees, or persons, it could be the case that they are dreaming and so it follows that the existence of those objects come into question. In other words, at any point of time, how can somehow be absolutely sure that they perceive real objects where in fact they could be dreaming.

The fact that someone can be deceived even once by their dreams is sufficient to cast all objects, regardless of their size or distance, into doubt. When making this conclusion, Descarte is assuming that people have been deceived by their dreams at least once, seeing as it is implausible that someone is able to know every single time with objective clarity whether or not they are dreaming. However, as we shall see, this point is irrelevant to Descarte’ further argument.

There are still some things that dream skepticism cannot cast into doubt, namely, one can trust simple and general beliefs whose truth does not depend on existing things. Shape, size, extension, number, place, time, are few examples that are real regardless of whether one is dreaming or awake.

The argument goes as follows: suppose I am dreaming at this very moment, even though I may be mistaken of the existence of such things as tables, trees, or persons, I cannot doubt the fact that they possess spatial-temporal properties, have a certain size, have some sort of continuing properties (time), or that simple mathematical properties such as 2 + 3 = 5 or that a square has four sides, must truly exist.

This objection points out that regardless of one’s dream state, to be able to even conceive such objects as tables, trees, or persons, in one’s dreams, it must be the case that certain universal properties such as time and extension exist since these properties are induced intrinsically into the objects just mentioned.

Further extrapolating this weak principle of belief, Descarte discusses the painter analogy. The analogy goes as follows: suppose a painter creates something that is non-existent, such as a 5-eyed hairy monster that has a head of a zebra, legs of a mule, and a tail of a lizard. Though such a thing does not exist, Descarte would argue that parts of it must exist, such as the fact that it has a head of a zebra or eyes, for the painter to even be able to conceive such a thing.

Furthermore, suppose one creates something utterly distinct from any worldly objects, still the colors that the painter instills must truly exist regardless if the object in question exists. The response of appealing to properties such as shape, time, extension, and the painter analogy both avoid the dream skepticism argument- in that they assert the existence of such things regardless of one's dreaming or waking state.

Descarte is still able to cast this weak principle into doubt by positing the existence of an evil genius that goes out of his way into deceiving everything one perceives. Even properties such as time, shape, and mathematical properties are non-existent, for the evil genius deceives us into believing such things as well. At this point it seems as if everything thing can be doubted by positing the existence of an evil genius, as Descarte concludes, “…I have persuaded myself that there is nothing in the world: no sky, no earth, no minds, no bodies…”

Descarte’ original intention for undergoing this type of self-examination, among other things, is to find out if there is something that he cannot doubt. The evil genius argument seems indemonstrable in that it casts a shadow of doubt in everything that we have taken granted thus far- even our own existence.

Descarte argues that there is something he cannot doubt in light of the evil genius argument: the fact that he can doubt implies that he must be a thinking thing, regardless of any attempt by the evil genius to deceive him into thinking that he is doubting, he is still a thinking thing. As discussed in section, one cannot doubt that one is doubting while one is doubting, it follows that just by virtue of being a thinking thing one exists necessarily: for every time I conceive of the following statement, “I am, I exist”, it must be the case that I exist, Descarte argues.

There are several objections that can be made in regards to Descarte’ conclusion, namely, “I am, I exist”. Descarte argues that so long as he pronounces the phrase “I am, I exist” it must be the case that he exists by virtue of being a thinking thing. An objection can be posed as follows: through the course of time, how can Descarte be absolutely sure that every time he exclaims- “I am, I exist”- the “I” is numerically the same “I” pronounced at some other time. This of course is the objection posed by Kant that appeals to the problem of personal identity over time.

Descarte would then be committed to saying that at least something existed at some time, which in some sense is a weaker claim than the original one. Another objection, authored by me, can be raised as follows: modern science has shown that a neurologist can stimulate the brain in such a way as to make the person blurt out a set of incoherent words or cause the person to move its arm without the individual’s own consent. When asked why he blurted out the words or raised his hand, he states that the actions were not of his own accord, though he acknowledges that such events did occur. Linking this point with Descarte’ notion of doubt, how can he be absolutely sure that it is not some ingenious neurologist, or evil genius, that is experimenting with his brain in such a way as to deceive him into thinking that his ‘doubt’ is of his own will, where in fact it is not, it just seems to be the case.

The analogy goes as follows: the man blurting out words is similar to Descarte’ notion of doubt, in both cases they are doing such things against their own will, however the man knows that his actions are that of the neurologist’s experimentation, whereas Descarte’ does not.

So in Descarte’ model, he perceives the doubting as that of his own will, which could not be further from the truth. It follows that Descarte’ original claim of being certain that he doubts is not so certain after all. To be precise, Descarte can only say that he seems to doubt, since he can never be sure if the doubting is in accordance of his own will or that of the neurologist, or evil genius. Consequently, Descarte is forced to make even a weaker claim, that is - “I seem to think therefore something exists”.

Bibliography:
Descarte, Rene. The Meditations.