Theo Todman's Web Page - Paper Abstracts

Author’s Abstract

1. In his book "Lewis (David) - Parts of Classes" (1991), David Lewis discusses the idea that composition is identity, alongside the idea that mereological overlap is a form of partial identity¹. But this notion of partial identity² does nothing to help Lewis achieve his goals in that book. So why does he mention it?
2. I explore and resolve this puzzle, by comparing Parts of Classes with Lewis’s invocation of partial identity³ in his 1993 paper "Lewis (David) - Many, But Almost One", where he uses it to address Peter Unger’s problem of the many⁴.
3. I raise some concerns about this way of thinking of partial identity⁵, but conclude that, for Lewis, it is an important defence against accusations of ontological profligacy.