 Although Kant agrees with Leibniz that there must be absolutely intrinsic properties for the world to exist as we know it, he differs with Leibniz about forces. In Kant’s view, forces are relational and thus not absolutely intrinsic (1781/1787: A265/B321; 1786: 498–91). He does not say whether there are Leibnizian primitive forces. And he denies that we know much about the nature of the absolutely intrinsic properties that, he thinks, must exist. Such knowledge would be tantamount to substantive knowledge of things-in-themselves, and famously he contends that we lack such knowledge. He could therefore be described as endorsing an epistemological doctrine that many contemporary Russellian monists endorse  (section 1.1):  we know little about quiddities beyond the theoretical roles they are supposed to play.