This chapter deals with McDowell’s views on the space of reasons and the space of nature, which forms the background to his conceptualist theory. I argue that McDowell draws the line between these spaces in such a way that only that part of our mental lives relevant to responsiveness to reasons – the conceptual part that is allegedly unique to humans – allows of taking in a viewpoint toward from which it is considered outside of the realm of natural law. Non-conceptual mental contents, by contrast, would fit unproblematically within the explanatory framework of the space of nature. I subsequently argue that this theory faces certain difficulties, and I discuss whether the Kantian and Husserlian frameworks might be able to avoid some of them. In the second half, I turn to McDowell’s realist intentions, in particular his interpretation of the Cartesian threat of idealism and his own response to this based on a disjunctive theory of perception. Here I argue that both the diagnosis of the problem as well as the solution to it are virtually identical to what was suggested by Kant in the fourth paralogism, who speaks of a ‘dualism’ (instead of a disjunct) in the same context.