Hume’s discussion of space in the Treatise addresses two main topics: divisibility and vacuum. It is widely recognized that his discussion of divisibility contains an answer to Bayle, whose Dictionary article “Zeno of Elea” presents arguments about divisibility as support for fideism. It is not so widely recognized that, elsewhere in the same article, Bayle presents arguments about vacuum as further support for fideism. This paper aims to show that Hume’s discussion of vacuum contains an answer to these vacuum-based fideistic (...) arguments. Key to this answer is a distinction between two ways in which vacuum was conceived in the early modern period: i) as a genuine thing that has spatial properties, and yet is immobile, indivisible, and penetrable ; ii) as a mere absence of spatial things. This paper also aims to provide a novel defense of Hume against the long-standing objection that he is inconsistent in denying that we can conceive of a vacuum, while allowing that we can conceive of “invisible and intangible distance.” As I interpret him, Hume consistently denies that we can conceive of a positive vacuum, while allowing that we can conceive of two or more objects’ being arranged so as to have privative vacuum between them. (shrink)

We do not fully understand Hume’s account of space if we do not understand his view of determinations of extension, which is too much ignored a topic. In this paper, I argue for an interpretation that determinations of extension are unities in Hume’s view: single beings in addition to their components. This realist reading is reasonable on both textual and philosophical grounds. There is strong textual evidence for it and no textual reason to reject it. Realism makes perfect sense of (...) the metaphysics of determinations of extension along Humean lines and Hume’s view of spatial relations. (shrink)