 Finally, as far as the third Postulate is concerned, it pertains to material necessity in existence, and not the merely formal and logical necessity in the connection of concepts. … Now there is no existence that could be cognized as necessary under the condition of other given appearances except the existence of effects from given causes in accordance with laws of causality. Thus, it is not the existence of things (substances), but only that of their state, about which we can cognize their necessity—and, indeed, from other states that are given in perception, in accordance with empirical laws of causality. 