Abstract

Thomas Reid presented a two-dimensional geometry of the visual field in his Inquiry into the Human Mind (1764). The axioms of this geometry are different from those of Euclidean plane geometry. The ‘geometry of visibles’ is the same as the geometry of the surface of the sphere, described without reference to points and lines outside the surface itself. In a recent article, James Van Cleve has argued that Reid can secure a non-Euclidean geometry of visibles only at the cost of abandoning his direct realist theory of perception, and reintroducing sense-data. The question will be reexamined by considering two aspects of Reid’s theory of vision: the claim that we do not directly perceive distance by sight and Reid’s characterization of visible figure as a partial notion of an external object.