the.com/law of excluded middle

means A foundational logic principle stating that for any proposition, either it or its negation must be true — there's no third option.

from Traces back to Aristotle's writings on logic, where it appears alongside the law of non-contradiction as one of the classical 'laws of thought.' The Latin tag 'principium tertii exclusi' (principle of the excluded third) came later, from medieval logicians formalizing his work. It's stood mostly unchallenged for over two thousand years — though some modern logics (like intuitionistic logic) deliberately reject it, insisting that 'not provably false' isn't the same as 'true.'