Abstract

Leibniz says that descartes maintains that a human soul brings about voluntary acts by changing the direction of motion of parts of its body without changing the total quantity of motion. Most subsequent commentators have endorsed this interpretation. But descartes does not say this anywhere, And says things inconsistent with this interpretation. The present paper attributes to descartes a complementarity doctrine, According to which the cartesian laws of motion do not apply to the behaviour of animated bodies, And argues that this doctrine is a natural outcome of his methodological practice of constructing theoretical models for particular classes of phenomena