Descartes Method of Doubt Rene

Descartes Method of Doubt

Rene Descartes' method of doubt first appeared in the Discourse and the First Meditations. Descartes' "method" was grounded in doubt. His program of systematic doubt sought to chip away all apparent knowledge, leaving only a clear and distinct residue that was certain. Applying this program, he arrived at the one affirmation about which he could have no doubt: Cogito, ergo sum (I think, therefore I am). In fact, the Discourse on Method is best known as the source of the famous quotation "Je pense, donc je suis" ("I think, therefore I am") (Hatfield, 12). He could not doubt his own existence, for the very act of doubting required his existence. Further, this experience of thinking did not necessitate a body that thought. Thus Descartes crystallized the distinction between body and mind (or soul) in the human as but one manifestation of a fundamental metaphysical dualism that pervaded his cosmological vision. Within the cosmos there were two distinct substances: material substance (matter) and mental (or spiritual) substance. The former was extension; the latter was thinking. The behavior of the former could be fully described in the terms of mathematical physics, while the latter could be understood only in philosophical or, ultimately, religious terms. Though Descartes made this dualism of substances central to his thought, he recognized it as problematic because the two presumably separate substances, mind and body, apparently interact as the human mind animates the body. At a fundamental level, this problem remained unsolved for Descartes. He did propose a physiological point at which the union of body and soul occurred: namely, the pineal gland.

The process begins with Inquiry that the Pure Enquirer seeks. It starts from a situation in which he has beliefs: beliefs which have been acquired in ways which he knows are not error-proof, so he knows with virtual certainty that some of his beliefs are false. Seeking, from his present perspective, to raise the truth-ratio to the absolute maximum, the first step is to preserve, out of his present beliefs, any that are genuinely certain, and the way to do that is to set aside the ones that are not. After doing that, the Pure Enquirer can then see how much and what he is left with, and judge from that how the pure project of truth-gathering is proceeding. This is the Method of Doubt, and exactly as Descartes claims in the Discourse, it is a rational consequence of adopting the perspective of one who wants to devote himself solely to the search for truth.(Broughton: p. 27)

But it is easier to introduce the notion of certainty at this point than to be clear about what it is. How exactly is 'certainty' to be taken? One line of approach here is to assume that in looking for beliefs that will be certain, one is looking for a kind of proposition - a kind which, when believed, must constitute true beliefs. The simplest definition of such a kind of proposition would be this: a proposition which is such that if someone believes it, then it logically follows that his belief is true. Lets call such a proposition incorrigible. 4 Acquiring beliefs which are incorrigible in this sense must be a sufficient condition of the Pure Enquirer's getting what he basically wants, truth, since anything incorrigible which he believes will be true. Moreover, the notion of incorrigibility is, unlike the bare concept of truth, a cognitive concept (it essentially involves a reference to belief), and in this respect shares an important feature with the notion of certainty. It is tempting to think that incorrigibility is a species of the certainty which the Pure Enquirer wants. However, we should be cautious about this, since it is not altogether obvious that 'collect incorrigible beliefs' is an epistemically effective maxim - perhaps the Enquirer could be deceived about which beliefs are incorrigible. This is a kind of difficulty which cannot be resolved here.

Another point - a more encouraging one, perhaps - is that incorrigibility might be only one species of certainty. There may be beliefs which are certain without being in this way incorrigible, and in that case it will not of course be a condition of the Enquirer's gaining certainty that he accept only propositions which are incorrigible. We shall come to a suggestion of this kind very soon. But however that may be, at least this seems not an unreasonable way for the Method of Doubt to start off: by rejecting what is not incorrigible. It may be too harsh, but if it can be carried out, it cannot be too lax.

If the Method does start off in that way, it follows at once that large classes of propositions ordinarily accepted will have to be rejected. Take propositions such as 'I can see a table', 'I heard a clap of thunder'; add to them propositions such as 'a table is over there' or 'that was a clap of thunder', which do not themselves mention perception, but which we believe on the strength of perception and which claim the existence of publicly perceptible objects or states of affairs: call all of these 'perceptual propositions'. Then no perceptual proposition is in the defined sense incorrigible, since, where 'p' is any such proposition, 'A believes that p but "p" is false' does not express a contradiction. If we are rejecting everything but the incorrigible, all perceptual propositions must go.

But this immediately reopens the question whether we should be rejecting everything but the incorrigible. Perhaps that program places the standards of certainty in the wrong place even for the demanding purposes of the Pure Enquirer? Take any perceptual proposition, such as 'I can see a table'. It is not incorrigible: but that says something only about a class of circumstances - all it means is that there could be some circumstances in which I believed that I was seeing a table, and that belief was false. But it does not follow that on any given occasion when I believe that proposition, it might on that occasion be false. The fact that the proposition is not incorrigible merely means that there are some occasions - for example, in a bad light, in an unfamiliar room, without my glasses - when I could believe wrongly that there was a table in front of me; but that undoubted fact does not mean that now, in good light, my wits about me and my glasses on, amid my familiar furniture, I can for all that properly think 'it is possible that there is no table there' or 'I might be wrong'.

In this respect, corrigibility is like contingency. The fact that a proposition is contingent - i.e. that it might (logically) have been false - does not entail that it might now be false. Descartes is sometimes accused of having mounted the Method of Doubt, or at least its application to perceptual and similar matters, on a confusion in that respect about contingency; but this is a mistake about Descartes. He is dealing with corrigibility, not contingency (his first important incorrigible truths will in fact be contingent). Moreover, he does not suppose that there is an immediate move even from the corrigibility of a proposition to its uncertainty in each given case. The Pure Enquirer needs further thoughts to arrive at that, and they occur in a transition which Descartes makes very clearly in both the Discourse Part iv and in the First Meditation. The transition is from the occasional errors of the senses, to the question of dreaming. The sort of error that consists in mistaking the shape of a distant tower - to take one of Descartes's examples - does not convey the possibility of error to each case of seeing a tower, still less to each case of perceiving anything; the 'errors of my dreams' may do so.