Full Idea
If we say 'for some x, x is F and x is G' we are making tacit appeal to the idea of identity in using 'x' twice here: it has to be the same object that is both F and G.
Clarification
F and G stand for properties
Gist of Idea
In 'x is F and x is G' we must assume the identity of x in the two statements
Source
Colin McGinn (Logical Properties [2000], Ch.1)
Book Reference
McGinn,Colin: 'Logical Properties' [OUP 2003], p.8
A Reaction
This may well be broadened to any utterances whatsoever. The only remaining question is to speculate about whether it is possible to think without identities. The Hopi presumably gave identity to processes rather objects. How does God think?