In the Metaphysical Foundations of Natural Science, Kant presents an argument for the centrality of <motion> to our concept <matter>. This argument has long been considered either irredeemably obscure or otherwise defective. In this paper I provide an interpretation which defends the argument’s validity and clarifies the sense in which it aims to show that <motion> is fundamental to our conception of matter.

Kant’s philosophy of natural science has traditionally concentrated on a host of issues including the role of laws of nature and teleological judgements. However, so far, the literature has made virtually no contact with the no less important tradition in Kant’s legal and political philosophy. This article explores one aspect of such connection in relation to the normative foundations of Kant’s notion of cosmopolitan right. I argue that Kant’s argument for cosmopolitan right is based on two main premises: the first (...) is what I call thelaw of equilibrium, and the second is thepremise of physical interaction(commerciumin Latin) at work behind what Kant called the original ‘community of land’. The article argues that the relevant notion of community quacommerciumshould be understood in the context of Kant’s metaphysics of nature as a ‘real community of substances’ governed by a dynamical law of equality of action and reaction. This metaphysical-causal interpretive reading has far-reaching implications for the foundations of cosmopolitan right and its scope of applicability well beyond Kant’s envisaged right to universal hospitality. (shrink)