The Law of Excluded Middle (LEM) is one of the three basic laws in classical logic. It says "Statements are either true or false." Or as have some put it, "A statement is true, or its negation is true.” Some reject this law and assert that there is a third option; namely, that the truth or falsity of the statement can be unknown. But, it would seem that being unknown does not negate the proposition that the statement is either true or false. It just means its truth or falseness is not known.