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Philosophy

Modal Logic and the Formalization of Necessity and Possibility

Quick fact

Modal logic gives a precise mathematical meaning to 'necessarily' and 'possibly' by using 'possible worlds'—alternative ways the universe could be. A statement is necessarily true if it holds in every possible world, and possibly true if it holds in at least one.

Why this is interesting

We all use words like 'must' and 'might' constantly. But how can we prove that something is 'necessarily' true, or that something else is 'possibly' true?