TheLawOfNoncontradiction

Variously formulated, the gist of the Law of Noncontradiction is that a proposition and its denial cannot both be true at the same time and "in the same respect." Actually, the latter formulation is known as ThePrincipleOfBivalence. If we're being careful, we won't formulate it this way. Instead, we'll say the law is: for any proposition P, it is not both the case that P and not-P.

The Law of Noncontradiction is almost universally affirmed by philosophers; there are many who deny ThePrincipleOfBivalence, however.