### Single Idea 15517

#### [catalogued under 6. Mathematics / B. Foundations for Mathematics / 6. Mathematics as Set Theory / a. Mathematics is set theory]

Full Idea

Renouncing classes means rejecting mathematics. That will not do. Mathematics is an established, going concern. Philosophy is as shaky as can be.

Gist of Idea

Giving up classes means giving up successful mathematics because of dubious philosophy

Source

David Lewis (Parts of Classes [1991], 2.8)

Book Reference

Lewis,David: 'Parts of Classes' [Blackwell 1991], p.58

A Reaction

This culminates in his famous 'Who's going to tell the mathematicians? Not me!'. He has just given four examples of mathematics that seems to entirely depend on classes. This idea sounds like G.E. Moore's common sense against scepticism.