All Alone in the Universe: Individuals in Descartes and Newton

In this paper we argue that the primary issue in Descartes' Principles of Philosophy, Part II, articles 1-40, is the problem of individuating bodies. We demonstrate that Descartes departs from the traditional quest for a principle of individuation, moving to a different strategy with the more modest aim of constructing bodies adequate to the needs of his cosmology. In doing this he meets with a series of difficulties, and this is precisely the challenge that Newton took up. We show that Descartes' questions and his strategy influenced not only Newton's account of physical bodies, but also the structure of his mechanics