  Desgabets’s most important Cartesian text, Supplément à la philosophie de M. Descartes (1675), was intended as a supplement to Descartes’s Meditations. In this work, Desgabets examines many of Descartes’s important doctrines and arguments. Desgabets defends the Cartesian doctrines of sensible qualities, matter, mind-body dualism, mind-body union and interaction in man while criticizing Descartes’s argument for the cogito as the first principle of knowledge, the claim that there is such a process as pure intellection, that there are innate ideas, and that ideas have objective reality (pure possibility). What is particularly interesting is the central importance that Desgabets gives to the role of sensation in knowledge, and his development of Descartes’s treatment of truth as both eternal and immutable but in some sense (one much contested in the literature) contingent. Desgabets more than once remarks in this work that “M. Descartes is not always a good Cartesian,” which typifies his conviction that Cartesianism is more than the sum of the particulars set down by Descartes himself.