Kant on the metaphysical foundation of inertia

This paper deals with Kant's elaboration of a metaphysical foundation of the principle of inertia in the Metaphysical Foundations of Natural Science. Many of Kant's contemporaries treat inertia not as an issue of mathematical physics but rather as a general feature of material objects that is addressed by metaphysics and, to some extent, by theology as well. In turn, inertia is often seen as the reason why matter is fundamentally passive, thus providing an argument against materialism. In particular, Abraham Gotthelf Kästner and Johann Samuel Traugott Gehler are considered on this score. They agree with Kant in that the principle of inertia follows from the general causal principle. Contrary to Kant, Kästner and Gehler treat inertia as a phenomenon of experience, whereas it seems a unique feature of Kant's approach to conceive of inertia as expressing the lifelessness of matter.