Abstract

I contend that in the "meditations" descartes expresses both certainty and doubt that he exists. He is certain that he exists when he views himself in terms of occurrent acts of thinking; his certainty stems from his "observing" such acts. When he views himself in terms of an "unobservable" thinking substance, The belief that acts are in a thinking substance is central. Thinking substances can be known to exist only by demonstrating that this belief is true, And the demonstration can only be accomplished by showing that a good God exists. Thus prior to such proofs, Descartes can doubt that he, Qua particular thinking substance, Exists. He does exhibit self-Doubt in the third meditation