Abstract

Book 1, Part 4, Section 5 of Hume’s Treatise is taken up with a response to an argument for the immateriality of the soul that Hume considered “remarkable,” and that Kant was later to describes as the “Achilles” (the strongest) of all the arguments for this conclusion. This paper surveys versions of the argument offered by Cudworth, Bayle, and Clarke before going on to argue that Hume’s own treatment of the argument departs from the standard in a number of important ways. The departures restate the argument in Humean terms, replacing premises concerning inherence, substance, and action, which Hume considered to be false or unintelligible, with ones mentioning conjunction at a location in space, which he considered to be at least intelligible. These changes challenge the view that Treatise 1.4.5 was intended as a satire or a lampoon. A satire or lampoon exposes a flat statement of its target view to ridicule. It does not modify that view— certainly not by way of introducing improvements to make it more intelligible. Hume meant to endorse what he said in Treatise 1.4.5. In particular, he meant to endorse the tenets that that there are mental states that are spatially extended, and that it is as difficult to explain how an immaterial soul could contain extended mental images as to explain how a material soul could contain unextended thoughts.