What is the method of doubt?

René Descartes, answered from the texts and cited to the page.

René Descartes answers

The doubts that alarmed you at the outset are like phantoms and vain images appearing in the night by the uncertain glimmer of a feeble light — fear pursues you if you flee, but if you approach and touch them, you will find nothing but wind and shadow.¹ The method proceeds by rejecting everything that can possibly be doubted, treating the doubtful not as merely uncertain but as though it were false, so that only what survives this most severe scrutiny can serve as a foundation for knowledge.²

We begin with the senses, which sometimes deceive us; we consider that we dream, that the deluded believe themselves to reason excellently while wanting any sense or judgment — and so we cannot with certainty distinguish sleep from the waking state.³ Even the demonstrations of mathematics fall under suspicion, for an omnipotent creator could perhaps have made us so that we are deceived even in what we believe ourselves to know best.⁴

Yet this universal doubt is not an end but a beginning — it is, as I put it in The Search after Truth, a fixed and unchangeable point from which I resolved to derive the knowledge of God, of the self, and of all that the world contains.⁵ The doubt turns on itself the moment it is pressed to its limit: you can doubt all things whose knowledge comes by the senses alone, but can you doubt your doubt?

There is a contradiction in conceiving that what thinks does not, at the same time as it thinks, exist.⁶ Hence the first and most certain of all conclusions for one who philosophises in an orderly way: I think, therefore I am. Now, my critic Bourdin charged in the Seventh Objections that the method is either nothing sound or nothing new — that if it means only the metaphysical abstraction by which the doubtful is set aside during an inquiry into what is certain, this is old and common to all philosophers; but if it means treating the doubtful as positively false, it is novel but erroneous.⁷

The charge misses the structure entirely.⁸ The method does not assert the falsehood of what is suspended; it suspends assent, which is a different act entirely — and our free will is precisely the faculty by which we may abstain from accepting as true and indisputable those things of which we have not certain knowledge, thus preventing us from ever being deceived.⁹ The nose is not removed to prevent the catarrh; the catarrh is prevented by learning, first, what a nose is.

Sources

1. those doubts which alarmed you to begin with, are like those phantoms and vain images which appear in the night by the uncertain glimmer of a feeble light. Fear pursues you if you flee, but if you approach and touch them, you will find nought but wind and shadow

   The Philosophical Works of Descartes Vol I

2. I desire then to set before myself all these difficulties in the strongest manner possible, and to apply myself to doubt whether I have not been dreaming all my life

   The Philosophical Works of Descartes Vol I

3. Do not delirious people, children, and madmen believe that they reason excellently, though wanting anything like sense and judgment?

   The Philosophical Works of Descartes Vol II - Objections and Replies

4. we have been told that God who created us can do all that He desires. For we are still ignorant of whether He may not have desired to create us in such a way that we shall always be deceived, even in the things that we believe ourselves to know best

   The Philosophical Works of Descartes Vol I

5. it is really from this universal doubt which is like a fixed and unchangeable point, that I have resolved to derive the knowledge of God, of yourself, and of all that the world contains

   The Philosophical Works of Descartes Vol I

6. we cannot in the same way conceive that we who doubt these things are not; for there is a contradiction in conceiving that what thinks does not at the same time as it thinks, exist

   The Philosophical Works of Descartes Vol I

7. And hence this conclusion I think, therefore I am, is the first and most certain of all that occurs to one who philosophises in an orderly way

   The Philosophical Works of Descartes Vol I

8. The Method contains either nothing sound, or nothing new; at most it contains what is superfluous. For if it alleges that by its renunciation of the doubtful it means what is called that Metaphysical abstraction by which what is doubtful is considered only as doubtful... what it says will be sound, but not at all new

   The Philosophical Works of Descartes Vol II - Objections and Replies

9. whoever turns out to have created us, and even should he prove to be all-powerful and deceitful, we still experience a freedom through which we may abstain from accepting as true and indisputable those things of which we have not certain knowledge, and thus obviate our ever being deceived

   The Philosophical Works of Descartes Vol I