### Single Idea 21721

#### [catalogued under 6. Mathematics / C. Sources of Mathematics / 6. Logicism / b. Type theory]

Full Idea

The higher types are needed for intensional phenomena, cases where the same class is picked out by distinct propositional functions.

Gist of Idea

Higher types are needed to distinguished intensional phenomena which are coextensive

Source

Bernard Linsky (Russell's Metaphysical Logic [1999], 6.4)

Book Reference

Linsky,Bernard: 'Russell's Metaphysical Logic' [CSLI 1999], p.101

A Reaction

I take it that in this way 'x is renate' can be distinguished from 'x is cordate', a task nowadays performed by possible worlds.