ABSTRACT
Rene Descartes defines the self as the thinking thing. Whenever there is thought, there is something that thinks the thought. For Descartes, substance means a stratum—that is, a layer—of reality, like matter in general in which material things exist permanently. It might be difficult to fathom the implications of Descartes's original mind–body distinction, given how commonplace it is today. The mind–body distinction leads Descartes to the problem of the existence of the external world. He attempts to solve this through a series of arguments that aim to prove God's existence. First he argues for the existence of God using the notion of "clear and distinct" ideas. Descartes subsequently offers another argument for the existence of God. One of the most important notions introduced by Descartes in his theological arguments is that of "clear and distinct ideas".
