Single Idea 15502

[catalogued under 4. Formal Logic / F. Set Theory ST / 3. Types of Set / b. Empty (Null) Set]

Full Idea

The null set is a denotation of last resort for class-terms that fail to denote classes, an intersection of x and y where they have no members in common, the class of all self-members, and the real numbers such that x^2+1=0. This is all mere convenience.

Gist of Idea

There are four main reasons for asserting that there is an empty set


David Lewis (Parts of Classes [1991], 1.4)

Book Reference

Lewis,David: 'Parts of Classes' [Blackwell 1991], p.11

A Reaction

A helpful catalogue of main motivations for the existence of the null set in set theory. Lewis aims to undermine these reasons, and dispense with the wretched thing.