Doubting, Thinking, and Possible Worlds

Kripke has noted that possible worlds are stipulated, not discovered, and that the stipulation of these worlds allows us to separate accidental from essential properties. In this paper I argue that possible worlds theory gives us an important tool for analyzing what Descartes is doing in the Meditations. The first Meditation becomes a thought experiment in which possible realities are stipulated in a search for one or more essential properties. Viewing the doubt in this manner sheds new light on the cogito and sum res cogitans and shows the limitations of some contemporary discussion of the cogito, namely, the positions taken by Ayer and Hintikka