 In “Reduction of Mind” (1994b), David Lewis separates his contributions to philosophy of mind into two broad categories. The first category is his reductionist metaphysics. From his first published philosophy paper, “An Argument for the Identity Theory” (1966a), Lewis defended a version of the mind-brain identity theory (see the entry on the  identity theory of mind).  As he makes clear in “Reduction of Mind”, this became an important part of his global reductionism. We’ll look at his metaphysics of mind in sections 4.1–4.3.