Abstract

In the Metaphysical Foundations of Natural Science (MFNS) Kant develops a conception of matter that is meant to issue in an alternative to what he takes to be the then reigning empiricist account of density. However, in recent years commentator after commentator has argued that Kant’s attempt on this front is faced with insuperable difficulties. Adickes argues that the MFNS theory of density involves Kant in a vicious circle; Tuschling argues that the circle is part of what led Kant to abandon the theory of matter developed in the MFNS; Förster argues that recognition of this circularity played a significant role in Kant’s development of the project now known as the Opus Postumum; and Westphal argues that the circularity problem serves to demonstrate the “untenability of Kant’s metaphysical method” and therefore helps to explain “the radical revision of the relation between mathematics and metaphysics Kant undertakes in his opus postumum.” Indeed, even Kant seems to think that his theory of density is circular: as noted by all of these commentators, in correspondence with one of his former students Kant declares that this theory “seems to lead however to a circle out of which I am not able to come.” Against this growing tide (and even, it seems, against Kant himself) I defend Kant’s theory of density. I argue that the suspicion of a circle results from a confusion of logical relations with causal conditions, and I argue that even Kant seems to have been taken in by this confusion.