Cartesian Circle - Modern Commentators

Modern Commentators

Bernard Williams presents the memory defense as follows: "When one is actually intuiting a given proposition, no doubt can be entertained. So any doubt there can be must be entertained when one is not intuiting the proposition." (p. 206) He goes on to argue: "The trouble with Descartes's system is not that it is circular; nor that there is an illegitimate relation between the proofs of God and the clear and distinct perceptions The trouble is that the proofs of God are invalid and do not convince even when they are supposedly being intuited". (p. 210)

As Andrea Christofidou explains:

"The distinction appropriate here is that between cognitio and scientia; both are true and cannot be contradicted, but the latter is objectively true and certain (with the guarantee of God), while the former is subjectively true and certain, that is, time-bound, and objectively possible (and does not need the guarantee of God)." (pp 219–220)

A more interesting defense of Descartes against the charge of circularity is developed by Harry Frankfurt in his book Demons, Dreamers, and Madmen: the Defense of Reason in Descartes' Meditations (Bobbs–Merrill, 1970; reprinted by Princeton University Press, 2007). Frankfurt suggests that Descartes' arguments for the existence of God, and for the reliability of reason, are not intended to prove that their conclusions are absolutely true, but to show that reason can be compelled to accept them, even in the face of radical sceptical arguments. In fact, according to Frankfurt, the validation of reason is accomplished by the rejection of the main sceptical hypothesis, which is the first real (albeit negative) conclusion of the argument, whilst the proposition about God's existence is a merely preparatory step. It must be conceded that once reached the real conclusion of the argument, the cartesian method would forbid the sceptic to reply that perhaps the cartesian proof was suggested to the meditator by the evil genius itself, in the first place (thereby accusing Descartes of vicious circularity). This accusation fails, since it requires the evil genius' possible existence to be still deemed a possibility – an idea which precisely, after the expanded "God's proof" the meditator has acquired a specific reason to reject.

However, according to Frankfurt the proof presupposes the validity of the principle of non-contradiction, since otherwise an argument leading to the (provisional) conclusion that a benevolent God exists, wouldn't force Descartes to reject the possible existence of the demon. Thus the proof might, after all, beg the question against a kind of scepticism radical enough to put in doubt the rule of non-contradiction.

Moreover, according to Frankfurt's Descartes, the meditator feels forced to accept his conclusion merely because of the evidence of the supporting argument, while Frankfurt himself started by explaining that the radical doubt is meant to be a criticism of evidence as a criterion of truth (even subjective truth, if you want). As Frankfurt pointed out, it seems hard to deny that the general proposition "evident statements can be false or misleading" can be thought without hindrance, and that Descartes seems to have countenanced this kind of doubt, when close to the end of the First Meditation he wrote that

"...as I sometimes think that others are in error respecting matters of which they believe themselves to possess a perfect knowledge, how do I know that I am not also deceived each time I add together two and three, or number the sides of a square, or form some judgment still more simple, if more simple indeed can be imagined?"

The outcome seems to be that a doubt aimed at evident ideas is supposed by Frankfurt to be overcome by means of a further evident idea, thereby begging the question. Frankfurt's ideas about the cartesian circle are further developed by Edwin Curley and Jose de Teresa.