Single Idea 18395

[catalogued under 4. Formal Logic / F. Set Theory ST / 1. Set Theory]

Full Idea

Lewis pointed out that many-membered classes are nothing more than the mereological wholes of the classes formed by taking the singleton of each member.

Gist of Idea

Sets are mereological sums of the singletons of their members


report of David Lewis (Parts of Classes [1991]) by David M. Armstrong - Truth and Truthmakers 09.4

Book Reference

Armstrong,D.M.: 'Truth and Truthmakers' [CUP 2004], p.118

A Reaction

You can't combine members to make the class, because the whole and the parts are of different type, but here the parts and whole are both sets, so they combine like waterdrops.