I argue that descartes' doubting of the external world does not rest on doubting the truth of clear and distinct ideas. in fact, he denies that we clearly and distinctly perceive the "existence" of material things. thus, their existence is not established through the validation of such ideas and we can understand why descartes' argument for their existence takes the form it does. i suggest that dreams lead him to conclude that the existence of material things is not clearly perceived (...) and to doubt their existence. (shrink)