Monads, Solidity and the Metaphysics of Bodies

In this paper I argue that Kant's investigation of the nature of bodies, although it was largely based on Newtonian science, was more dependent on notions and debates in German logic and metaphysics. In section 1, I introduce the role of material substance in the Metaphysical Foundations of Natural Science, arguing that the systematic framework of Kant's "metaphysics of corporeal nature"cannot be described as a "foundation of Newtonian philosophy"and is best understood in the context of the reception of Newton's physics in Wolffian metaphysics. In section 2, I analyze the crucial role of monads, monadology and materialism in the development of Kant's dynamics. In section I3, I address Kant's "continuum"theory of matter in the Metaphysical Foundations, pointing out that it depended on non-Newtonian (or post-Newtonian) models. In section 4, I examine the methodological background of Kant's critique of the "solidity"of bodies, tracing it back to Kant's earlier debate on the method of science and metaphysics with Johann Heinrich Lambert.