BODIES, LAWS AND THE PROBLEM OF SECONDARY CAUSATION IN DESCARTES' NATURAL PHILOSOPHY

One of the main problems of Descartes's natural philosophy is the reconstruction of bodies in interactions and of the forces associated with them. It is a problem bearing on various important philosophical issues, from the interaction between God and matter, to the famous problem of secondary causation. The main problem of such attempt is that in Descartes' system, bodies are no more than extended geometrical shapes. There have been several recent debates in the literature bearing on various interpretations of Descartes' problem and the possible reconstruction of forces. My paper discusses some of them, while pointing to the significant difference between those interpretations focusing on associated metaphysical issues, and the specific questions connected with the physics of interactions. Then, I try to reconstruct Descartes' famous problems of collisions, pointing to the specific definition of physical bodies associated with the second part of the Principes. The paper demonstrates that in the attempt to reconstruct a new physics, Descartes gave a definition of physical bodies that leads to a very peculiar way of dealing with secondary causes and interactions.