Abstract

How can a Cartesian idea represent ordinary physical objects? One possibility is that Descartes holds a theory of natural signs according to which ideas, including sensations, represent states of the external world that are correlated with them. I deny that Descartes has a theory of natural signs in this sense, arguing, instead, that our perception of ordinary physical objects is achieved not through ideas, properly speaking, but through a special act of the mind which projects its sensations onto objects in the external world, objects truly represented by ideas of primary qualities alone. This ”projection” comprises referral judgments that account for the characteristic phenomenology of experience of the physical world but in a way that misleads us to think that our ideas bear a resemblance to the underlying metaphysical reality of the physical world. Other issues discussed include Descartes's taxonomy of ideas.