Abstract
1. Readers of Hume, even those who call attention to the depth and variety of his skeptical excursions, now happily admit that Hume is, in crucial respects, a “naturalist.” A naturalist is, broadly, someone who emphasizes the natural sources of our beliefs, attitudes, and practices; and Hume surely is at least this kind of naturalist. But understanding Hume’s naturalism to include only this general explanatory commitment obscures as much as it reveals, I will argue, about the text of Treatise I iv, where Hume examines various skeptical “systems of philosophy.” To understand that part of the Treatise, we must, I will argue, understand Hume’s shifting allegiances to different kinds of naturalism.