Full Idea
Anyone who denies the principle of non-contradiction simultaneously affirms it; it cannot be rationally criticised, because it is presupposed by all rationality.
Gist of Idea
You cannot rationally deny the principle of non-contradiction, because all reasoning requires it
Source
J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.12)
Book Reference
Baggini,J and Fosl,P.S.: 'The Philosopher's Toolkit' [Blackwells 2003], p.37
A Reaction
Nietzsche certainly wasn't afraid to ask why we should reject something because it is a contradiction. The 'logic of personal advantage' might allow logical contradictions.