Full Idea
Since any definition is an identity, identity itself cannot be defined.
Gist of Idea
Identity cannot be defined, because definitions are identities
Source
David Wiggins (Sameness and Substance [1980], 1.2 n7)
Book Reference
Wiggins,David: 'Sameness and Substance' [Blackwell 1980], p.21
A Reaction
This sounds too good to be true! I can't think of an objection, so, okay, identity cannot possibly be defined. We can give synonyms for it, I suppose. [Wrong, says Rumfitt! Definitions can also be equivalences!]
Related Idea
Idea 9585 Since every definition is an equation, one cannot define equality itself [Frege]