- non-contradiction, principle of
- (
*or law of*)The law of logic that it is not the case that (*p*& not-*p*). Contradiction is the final logical stopping-point: if we can derive a contradiction from a set of premises, then at least one of them is false (see*reductio ad absurdum*). If we ask what is so bad about contradiction, one answer is that a contradiction cannot be true (classically, if one conjunct*p*is true, then the other not-*p*is false, and vice versa, so they cannot be true together; see also negation ). Another answer is that from a contradiction anything whatsoever can be derived, which is true in classical logical systems. See dialetheia ; strict implication, paradox of.

*Philosophy dictionary.
Academic.
2011.*

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