 We can think of any objects whatsoever using the categories. In fact, this is unavoidable; the categories are the most basic concepts of objects in general, so we cannot think about anything whatsoever without using some categories to do so. But in thinking about the things in themselves using categories we do not thereby (a) know that there are things in themselves falling under the categories or (b) even that it is possible for there to be things in themselves falling under the categories. The strongest form of Jacobi’s objection—that Kant’s view entails that the categories cannot be applied, even in thought, to things in themselves—may rest on a misunderstanding (cf. Van Cleve 1999: 137; Adams 1997: 820–1). This still leaves, though, the pressing problem of how, given Kant’s Humility doctrine, he could have any epistemic warrant for making the various substantive claims he does about things in themselves (Existence, Non-spatiality, Affection).