Abstract

Locke claims that we have sensitive knowledge of the external world, in virtue of the fact that simple ideas are real, true, and adequate. However, despite his dismissive remarks about Cartesian external-world skepticism, Locke gives us little to go on as to how knowledge of the external world survives the fact of perceptual error, or even how perceptual error is possible. I argue that Locke has an in-principle problem explaining perceptual error.