Full Idea
Those who regard the conjunction p.not-p as true think they are talking about negation, 'not', but this ceases to be recognisable as negation. The deviant logician's predicament is when he tries to deny the doctrine he only changes the subject.
Gist of Idea
If you say that a contradiction is true, you change the meaning of 'not', and so change the subject
Source
Willard Quine (Philosophy of Logic [1970], Ch.6)
Book Reference
Quine,Willard: 'Philosophy of Logic' [Prentice-Hall 1970], p.81
A Reaction
The charge of 'changing the subject' has become a classic move in modern discussions of non-standard logics. It is an important idea in discussions of arguments, and is found in Kant's account of the Ontological Argument.