Philosophy Index

Law of the Excluded Middle

The Law of the Excluded Middle is a law in logic, which states that for any sentence (or proposition), that sentence is either true or false. This is equivalent to saying that truth and falsity are the only truth values for a sentence, and that no well-formed sentences are simultaneously not true and not false.

The Law of the Excluded Middle is often stated as the axiom: (φ ⋁ ¬φ).