Encyclopedia of Philosophy: The Doubt and the Cogito - DESCARTES

« Descartes insisted that the first task in philosophy is to rid oneself of all prejudice by calling in doubt all that can be doubted.

The second task of the philosopher, having raised these doubts, is to prevent them leading to scepticism. This strategy comes out clearly in Descartes' Meditations.

As the title suggests, the work is not intended to be read as an academic treatise.

It is meant to be followed in the frame of mind of a religious retreat, such as St Ignatius Loyola's Spiritual Exer¬cises.

It is to provide a form of thought therapy, detaching the mind from false approaches to the truth in the way that religious meditation detaches the soul from the world and the flesh. In this intellectual discipline, the deliverances of the senses are called in ques¬tion, first by considerations drawn from sense-deception, and then by an argument from dreaming. What I have so far accepted as true par excellence, I have got either from the senses or by means of the senses. Now I have sometimes caught the senses deceiving me; and a wise man never entirely trusts those who have once cheated him. But although the senses may sometimes deceive us about some minute or remote objects, yet there are many other facts as to which doubt is plainly impossible, although these are gathered from the same source; e.g.

that I am here, sitting by the fire, wearing a winter cloak, holding this paper in my hands, and so on. A fine argument! As though I were not a man who habitually sleeps at night and has the same impressions (or even wilder ones) in sleep as these men do when awake! How often in the still of the night, I have the familiar conviction that I am here, wearing a cloak, sitting by the fire – when really I am undressed and lying in bed! But even if the senses are deceptive, and waking life is as illusory as a dream, surely reason can be relied on, and the knowledge of a science such as mathe¬matics is secure! Whether I am awake or asleep, two and three add up to five, and a square has only four sides; and it seems impossible for such obvious truths to fall under a suspicion of being false. But there has been implanted in my mind the old opinion that there is a God who can do everything, and who made me such as I am.

How do I know he has not brought it about that, while in fact there is no earth, no sky, no extended objects, no shape, no size, no place, yet all these things should appear to exist as they do now? Moreover, I judge that other men sometimes go wrong over what they think they know perfectly well; may not God likewise make me go wrong, whenever I add two and three, or count the sides of a square, or do any simpler thing that might be imagined? But perhaps it was not God's will to deceive me so; he is after all called supremely good. But even if God is no deceiver, how do I know that there is not some evil spirit, supremely powerful and intelligent, who does his utmost to deceive me? If I am to avoid the possibility of assenting to falsehood, I must consider that all external objects are delusive dreams, and that I have no body but only a false belief in one. These doubts are brought to an end by Descartes' famous argument for his own existence.

However much the evil genius may deceive him, it can never deceive him into thinking that he exists when he does not.

‘Undoubtedly I exist if he deceives me; let him deceive me as much as he can, he will never bring it about that I am nothing while I am thinking that I am something.' ‘I exist' cannot but be true when thought of; but it has to be thought of to be doubted.

Once this is seen ‘I exist' is indubitable, because whenever I try to doubt it I automatically see that it is true. Descartes' argument is usually presented in the terser form he used in the Discourse: Cogito, ergo sum: ‘I am thinking, therefore I exist'.

From these few words Descartes not only derives a proof of his existence, but also seeks to dis¬cover his own essence, to demonstrate the existence of God, and to provide the criterion to guide the mind in its search for truth.

No wonder that every word of the cogito has been weighed a thousand times by philosophers. ‘I am thinking'.

What is ‘thinking' here? From what Descartes says elsewhere, it is clear that any form of inner conscious activity counts as thought; but of course the thought in question here is the self-reflexive thought that he is think¬ing.

How important is the ‘I' in ‘I am thinking'? In ordinary life the word ‘I' gets its meaning in connection with the body which gives it utterance; is someone who doubts whether he has a body entitled to use ‘I' in a soliloquy? Some critics have thought that he should really have said only ‘There is thinking going on'. ‘Therefore'.

This word makes the cogito look like an argument from a premiss to a conclusion.

Elsewhere Descartes speaks as if his own existence is something he intuits immediately.

Accordingly, there has been much discussion whether the cogito is an inference or an intuition.

Probably Descartes meant it to be an infer¬ence, but an inference that was immediate, rather than one which presupposed some more general principle such as ‘Whatever is thinking exists'. ‘I exist'.

If the premise should have been ‘thinking is going on', should the conclusion be only ‘existing is going on'? Critics have argued that the doubting Descartes has no right to draw the conclusion that there is an enduring, sub¬stantial self.

Perhaps he should have concluded rather to a fleeting subject for a transient thought; or perhaps, even, there can be thoughts with no owners.

Can Descartes assume that the ‘I' revealed by the methodical doubt is the same person who, unpurified by doubt, answered to the name of ‘René Descartes'? Once the link has been severed between body and mind, how can anyone be certain of the identity of the thinker of the Meditations? These questions have been pressed with great force in the philosophy of the last two centuries.

In Descartes' own time, it was asked how ‘I am thinking, therefore I exist' differs from ‘I am walking, therefore I exist'.

Descartes' answer is that as an argument the one is as good as the other; but the premiss of the first is indubitable, whereas the premiss of the second is vulnerable to doubt.

If I have no body, then I am not walking, even if I believe I am; but however much I doubt, then by the very fact of doubting, I am thinking.

But ‘I think I am walking, therefore I exist' is a perfectly valid form of the cogito.. »