Full Idea
A theory of non-spatiotemporal parts of things, whether recurring universals or non-recurring tropes, makes good sense of some abstractions. Unit negative charge is a universal common to particles, and an abstraction by being part of them.
Gist of Idea
If universals or tropes are parts of things, then abstraction picks out those parts
Source
David Lewis (On the Plurality of Worlds [1986], 1.7)
Book Reference
Lewis,David: 'On the Plurality of Worlds' [Blackwell 2001], p.85
A Reaction
He cautiously refers to 'some' abstractions. It is one of Donald Williams's proud boasts concerning his trope theory that it will handle this problem well. I'm not sure that we should be saying that abstractions are actually concrete bits of things.
Related Idea
Idea 8906 If we can abstract the extrinsic relations and features of objects, abstraction isn't universals or tropes [Lewis]