Full Idea
In the face of the conflict between mereology and set theory, Lewis has advocated giving up the existence of singletons rather than sums.
Gist of Idea
Lewis prefers giving up singletons to giving up sums
Source
report of David Lewis (Parts of Classes [1991]) by Kit Fine - Replies on 'Limits of Abstraction' 1
Book Reference
-: 'Philosophical Studies' [-], p.372