In this article, I have a modest goal: (1) to sketch how Kant can avoid the charge of subjective idealism advanced against him by John McDowell and (2) to do so with reference to Kant's last work, the so-called Opus Postumum. I am interested in defending Kant on this point because doing so not only (a) shows how we need notat least not because of this point about idealismjump ship from Kant to Hegel (as McDowell and others think), but also (b) suggests that the Opus Postumum is a text that ought to be explored more by Kantians and those interested in Kant. A subsidiary, implicit point is that (c) we need not shy away from McDowell's reading of Kant in order to oppose McDowell's criticism of Kant. In order to defend against McDowell's charge, I focus on the argument of the Refutation of Idealism, showing how this argument evolves in Kant's later works, especially the Opus Postumum.