Defending Kant’s conception of matter from the charge of circularity

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. Indeed, even Kant seems to have thought that his theory of density is circular, and some of these commentators argue that this is, at least in part, what spurred Kant on to develop the theory of matter found in the Opus Postumum. Against this growing tide (and even, it seems, against Kant himself) I defend Kant’s theory of density. I shall not take a stand on whether the circularity problem played a role in the development of the Opus Postumum theory of matter – my point is simply that if the circularity problem was the sole trigger for that move, then the move was unwarranted.