Descartes on Representation, Presentation, and the Real Natures

This dissertation concerns two controversial aspects of Descartes’ philosophy. The first is the meaning of the distinction between the material and objective senses of the word “idea.” The second is an alleged tension between the Fifth Meditation’s claim that the real natures are mind-independent and the claim of the Principles that universals are mind-dependent.

In the first chapter, I take up the material sense, and argue against those interpretations which see it as a category for the contentless ontology of ideas. I argue that the textual evidence points to the material sense being Descartes’ category for phenomenological description of how things seem to be to a given mind when it has a given idea. In particular, I argue that he deploys the material sense in his discussions of abstractions and that this points to the material sense being a category for content that lacks existential implication for the extramental world.

In the second chapter, I take up the ontology of the real natures, and suggest that there is no tension between the Fifth Meditation and the Principles because Descartes accepts two things under the term “nature,” namely, universals and individual essences. I suggest Descartes is committed to Platonism about individual essences in the Fifth Meditation, and that in the Principles he is concerned only with universals, about which he is a conceptualist. I further suggest that individual essences play key roles in both singular and universal thought.

In the third chapter, I take up the objective sense, and the widespread interpretation of this sense of ideas as concerning current presentational or phenomenological content. I suggest that this account struggles with cases where there is stability in the object of thought paired with changes in the associated phenomenology. I propose that we ought to reject a straightforward equation of the objective sense with current presentational content, and instead adopt a scheme according to which what has objective being in an idea is the sum total of thinkable, essential features of the object, and that when an idea is clear and distinct, what we perceive has objective being in the idea.