(as the case may be), we are given the truth or falsehood of the negation, disjunction, conjunction, incompatibility, or implication. A function of propositions which has this property is called a "truth-function."
The whole meaning of a truth-function is exhausted by the statement of the circumstances under which it is true or false. "Not-
," for example, is simply that function of
which is true when
is false, and false when
is true: there is no further meaning to be assigned to it. The same applies to "