ABSTRACT
Having obtained, in his Meditations, the certainty of his existence of a thing that thinks, and having decided that the mark of this primitive certainty (concerning things that exist, at least) is clear and distinct perception, Descartes looked to his own consciousness for clues to other existing things. His epistemological problem about the external world thus began with the here-andnow certainty of his mental existence and the here-and-now uncertainty of anything else - in particular, of anything external to his "inner" domain. The basic problem was how, starting from the here-and-now certainty of his current existence and state of mind, he could gain certain knowledge of an ambient world.
