Abstract

The leading idea of this chapter is that, for Descartes, intellectual ideas make it obvious what metaphysical category the properties they disclose to the mind fall into but not whether they are actually exemplified; sensations make it obvious whether the properties they disclose to the mind are exemplified but not what their metaphysical category is. This idea is worked out through a discussion of three stages in the development of Descartes's doctrine of the material falsity of sensory ideas, the core concept of his error explanation of the senses. Material falsity is a set of three defects that sensations have in comparison with intellectual ideas, ideas that fully discharge the role, which Descartes assigns to ideas in his philosophical system. The first stage, reflected in Meditation III, identifies material falsity with two defects: nonrepresentation and misrepresentation ; the second stage, reflected in the Reply to Arnauld, identifies material falsity with obscure ideas ; the third stage, reflected in the Principles of Philosophy I, sees the terminology of material falsity disappear and the terminology of clear but not distinct ideas appear. Other topics discussed include a special application of the rule of truth and skepticism.