Will, Doubt, Logic

With his doubt of Mathematics, Descartes' investigation surpasses the sphere of sensory information. However, he leaves unquestioned at least some of the principles of Logic. The thesis that he cannot doubt that he is doubting presupposes the validity of the Law of Contradiction, as does his reliance throughout on inferences, including those involved in his proofs of the existence of God. Without such presuppositions, his method illustrates the Logic of Will--indefinite diversification.