more on this theme | more from this thinker | more from this text
Full Idea
Identity is relative. When one says 'x is identical with y' this is an incomplete expression. It is short for 'x is the same A as y', where 'A' represents some count noun understood from the context of utterance.
Gist of Idea
Identity is relative. One must not say things are 'the same', but 'the same A as'
Source
Peter Geach (Reference and Generality (3rd ed) [1980], p.39), quoted by John Perry - The Same F I
Book Ref
'Metaphysics - An Anthology', ed/tr. Sosa,E. /Kim,J. [Blackwell 1999], p.90
A Reaction
Perry notes that Geach's view is in conscious opposition to Frege, who had a pure notion of identity. We say 'they are the same insofar as they are animals', but not 'they are the same animal'. Perfect identity involves all possible A's.