Abstract

The claim that Descartes could have derived the certainty of his existence from the infallibility of the self?referential use of T is rejected because it fails to take account of the hyperbolical hypothesis. Recognizing the constraints which the latter involved, Descartes tried to secure Sum by an argument in modus ponens, which requires an incorrigible statement about experience as a minor premiss. Because he had an incorrect conception of the nature of statements, Descartes failed to realize that the circumstances described in the hypothesis exclude the conditions necessary for any statements or thoughts whatsoever. This, in turn, led to a systematic conflation of statements with sentences. The incoherence of the argument follows from the fact that Cogito could at best be a sentence and not a statement and, as such, could not provide the required minor premiss. It is a further consequence of Descartes's conflation of statements with sentences that the subject of the hypothesis cannot be identical with the subject responsible for the hypothesis and that Descartes's hypothesis cannot therefore be about himself