# Principle of Bivalence | | In logic, the semantic **Principle of Bivalence** states that every declarative sentence expressing a proposition has exactly one truth value, either true or false. A logic satisfying this principle is called a two-valued logic or bivalent logic. | |-|-| | | wikipedia:: [Principle of bivalence](https://en.wikipedia.org/wiki/Principle_of_bivalence) | In logic, the semantic principle (or law) of bivalence states that every declarative sentence expressing a proposition (of a theory under inspection) has exactly one truth value, either true or false. [1][2] A logic satisfying this principle is called a two-valued logic[3] or bivalent logic. ## Criticisms ### Future Contingents the Polish formal logician [Jan Łukasiewicz](https://en.wikipedia.org/wiki/Jan_%C5%81ukasiewicz "Jan Łukasiewicz") proposed three truth-values: the true, the false and the _as-yet-undetermined_. - not unlike [[Mu (negative)]] - unasking the question ### Vagueness