 In response to the Ontological Argument, the argument that since perfection implies existence, the idea of a non-existent, perfect God is self-contradictory, Russell points out that the argument rests ultimately on the mistaken claim that existence is a property or, in Russell’s terminology, a predicate. His reasoning is as follows: If existence were a predicate then, like all other predicates, it would (or would not) be part of the nature of any given substance. But upon being created, each such substance would acquire a new predicate. “Hence the special position of existence, as a contingent and synthetic predicate, falls to the ground. If all substances always contain all their predicates, then all substances always contain or do not contain the predicate existence, and God must be as powerless over this predicate as over any other. To add the predicate existence must be metaphysically impossible. Thus, either creation is self-contradictory, or, if existence is not a predicate, the ontological argument is unsound” (1900, sec. 115, p. 185).