No Abstract In his graduate-seminar lectures on Kant—published as Kant and Pre-Kantian Themes (Sellars, 2002)—Wilfrid Sellars argues that because Hume cannot distinguish between a vivacious idea and an idea of something vivacious he cannot account for the human ability to represent temporally complex states of affairs. The first section of this paper aims to show that this argument is not properly aimed at the historical Hume who can, on a proper reading, distinguish these kinds of representations. This is not, however, (...) Sellars’ only argument for this conclusion. The next section of this paper continues with a discussion of an argument that Sellars presents on Kant’s behalf in Science and Metaphysics, and its key Kantian premise that, contra Hume, only conceptual representations can represent any complex states of affairs as such. The conclusion of this discussion is that Sellars does indeed present compelling reasons for rejecting a Humean account, reasons centered on the ambiguity of the associative structure of mental representation (which Sellars subsequently replaces with inferential structure). The paper concludes with an examination of the sense in which non-conceptual representations—such as those that Hume considers—represent and the role that these play in conceptual representation for both Sellars and Kant. (shrink)