Routledge History of Philosophy Volume IV

192 RENAISSANCE AND SEVENTEENTH-CENTURY RATIONALISM
as physics) whose truth depends on the actual existence of objects is potentially
doubtful; and that we may rely with certainty only on subjects like arithmetic and
geometry, which deal ‘with the simplest and most general things, regardless of
whether they exist in nature or not’. 32
At this stage in the First Meditation Descartes launches into a far more
disturbing and extreme doubt, which takes us into the heart of his metaphysics—
the possibility of error even concerning the simplest and apparently most selfevident
truths of mathematics. This possibility is initially introduced by invoking
an idea which was much misunderstood by Descartes’s contemporaries, that of
divine deception. Some found the suggestion impious; others saw the thrust of
the argument as leading to atheism. 33 But in fact the project of the First
Meditation, which is essentially one of suspension of belief, does not permit any
assumptions to be made, one way or another, about the existence of God.
Instead, we are presented with a simple dilemma: if there is an all-powerful
creator, then he could ‘bring it about that I go wrong every time I add two and
three or count the sides of a square’; if, on the other hand, there is no God, then I
owe my existence not to a divine creator but to chance, or some other chain of
imperfect causes, and in this case there is even less reason to believe that my
intuitions about mathematics are reliable. 34 What the argument appears to do, in
effect, is to cast doubt on the most basic perceptions of our intellect —on what
Descartes had earlier, in the Regulae, called our intuition of the ‘simple natures’.
But if the basic building-blocks of our knowledge are called into question, if the
very framework of human cognition is suspect, then how could any cognitive
process conceivably be validated?
Descartes’s strategy in dealing with the dilemma he has raised is to show that
even the most extreme doubt is self-defeating. ‘I immediately noticed’, he writes
in the Discourse, ‘that while I was trying in this way to think everything false, it
was necessary that I, who was thinking this, was something’. 35 In the
Meditations, essentially the same point is made, but in a rather more vivid way:
having dramatized the extreme level of doubt by deliberately imagining a
‘malicious demon of the utmost power and cunning who employs all his energies
in order to deceive me’, Descartes triumphantly exclaims:
In that case I too undoubtedly exist, if he is deceiving me; and let him
deceive me as much as he can, he will never bring it about that I am
nothing so long as I think that I am something. So… I must finally conclude
that this proposition, I am, I exist, is necessarily true whenever it is put
forward by me or conceived in my mind. 36
Elsewhere expressed in the famous dictum Cogito ergo sum (‘I am thinking,
therefore I exist’), this is the ‘Archimedean point’—the first indubitable certainty
which the meditator encounters; it is, says Descartes, ‘so firm and sure that all
the most extravagant suppositions of the sceptics are incapable of shaking it’, and