It is a widely held doctrine at the moment that metaphysical propositions are meaningless, are, in fact, not genuine propositions at all. This doctrine is supported by the contention that only propositions which are verifiable are significant: and it is held that metaphysical propositions do not fulfil this condition, and are consequently pseudo-propositions. Those who hold this view divide propositions into three classes: (I) Tautologies; which are analytic, certain, and are guaranteed by the principle of contradiction. (2) Factually significant propositions; which are synthetic, hypothetical, and are capable of empirical verification. (3) Pseudopropositions, which only appear to be propositions and are, in reality, meaningless nonsense.