### Single Idea 10811

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

Full Idea

The null set serves two useful purposes. It is a denotation of last resort for class abstracts that denote no nonempty class. And it is an individual of last resort: we can count on its existence, and fearlessly build the hierarchy of sets from it.

Gist of Idea

The null set plays the role of last resort, for class abstracts and for existence

Source

David Lewis (Mathematics is Megethology [1993], p.09)

Book Reference

-: 'Philosophia Mathematica' [-], p.9

A Reaction

This passage assuages my major reservation about the existence of the null set, but at the expense of confirming that it must be taken as an entirely fictional entity.