Leibniz and "Leibniz' Law"

Abstract

Passages in leibniz which have been understood to contain his statement of leibniz law do not in fact contain any statement of that principle. some of these passages contain a statement of the principle of the identity of indiscernibles, while others contain a statement of a principle about concept identity. the latter principle states that a concept, a, is identical with a concept, b, if and only if a can be substituted for b in any proposition without change of truth value.