In Three Dialogues Between Hylas and Philonous, Berkeley attempts to show that believing in mind-independent matter leads to absurdity and skepticism. Berkeley invites us to accept instead the doctrine of idealism, where the only things that exist are minds and ideas. Philonous - the spokesperson for Berkeley's considered view - uses several different kinds of argument to convince Hylas of idealism. In this paper I will investigate one type of argument that Philonous offers. Philonous claims that we cannot form abstract ideas, and suggests that the impossibility of abstract ideas deprives Hylas of an otherwise promising conception of mind-independent matter (pp. 28-30). I will show that, contrary to Philonous' claims, abstract ideas are possible. This will not by itself prove that matter exists. If I am right, however, then Hylas can argue that our idea of matter is an abstract idea.…
