Single Idea 18137

[catalogued under 2. Reason / D. Definition / 8. Impredicative Definition]

Full Idea

Poincaré suggested that what is wrong with an impredicative definition is that it allows the set defined to alter its composition as more sets are added to the theory.

Gist of Idea

Impredicative definitions are wrong, because they change the set that is being defined?

Source

David Bostock (Philosophy of Mathematics [2009], 8.3)

Book Reference

Bostock,David: 'Philosophy of Mathematics: An Introduction' [Wiley-Blackwell 2009], p.252