Abstract: In this paper I consider recent attempts to establish that the geometry of visual experience is a spherical geometry. These attempts, offered by Gideon Yaffe, James van Cleve and Gordon Belot, follow Thomas Reid in arguing for an equivalency of a geometry of ‘visibles’ and spherical geometry. I argue that although the proposed equivalency is successfully established by the strongest form of the argument, this does not warrant any conclusion about the geometry of visual experience. I argue, firstly, that (...) the resistance of this contemporary argument to empirical considerations counts against its plausibility. Moreover, I argue that the contemporary approach provides no compelling reason for supposing that the geometry offered as the geometry of ‘visibles’ is the correct geometrical description of visual experience. (shrink)

Thomas Reid (1710–1796) presented a two-dimensional geometry of the visual field in his Inquiry into the human mind (1764), whose axioms are different from those of Euclidean plane geometry. Reid’s ‘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. Interpreters of Reid seem to be divided in evaluating the significance of his geometry of visibles in the history of the discovery of non-Euclidean geometries. (...) The question will be reexamined with particular attention given to his unpublished manuscripts. These include comments on Saccheri’s work and Reid’s repeated attempts to derive Euclid’s parallel postulate from the axioms of incidence. (shrink)

Two theses appear to be central to Reid’s view of the visual field. By sight, we do not originally perceive depth or linear distance from the eye. By sight, we originally perceive the position that points on the surface of objects have with regard to the centre of the eye. In different terms, by sight, we originally perceive the compass direction and degree of elevation of points on the surface of objects with reference to the centre of the eye. I (...) consider various problems about distance perception and perception of position with regard to the centre of the eye raised by Reid’s texts. These questions are relevant to Reid’s description of the geometry of visibles as the “intrinsic” geometry of the surface of the sphere. (shrink)

Reid declared Hume's appeal to variation in the magnitude of a table with distance to be the best argument that had ever been offered for the ‘ideal hypothesis’ that we experience nothing but our own mental states. Reid's principal objection to this argument fails to apply to minimally visible points. He did establish that we have reason to take our perceptions to be caused by external objects. But his case that we directly perceive external objects is undermined by what Hume (...) had to say about the role played by color in our perception of the primary qualities of bodies. (shrink)

Reid's Inquiry into the Human Mind on the Principles of Common Sense devotes more space to double vision than to any other topic. In what follows, I examine why this subject was so important to Reid and why he dealt with it as he did. I also consider whether his argument for his position begs the question against his main opponents, Berkeley and Robert Smith. I show that, as Reid presented it, it does, but that he could have said more (...) than he did in reply to Smith. My discussion of why double vision was important for Reid begins with an exposition of the relevance of the theory of vision for one of Reid's principal concerns in the Inquiry: the concern to respond to scepticism concerning our knowledge of an external world. I then turn to consider how Reid's account of double vision contributes to his epistemological realism and why the alternative account offered by Berkeley and Smith challenges it. (shrink)

(Originally published in _Reid Studies_ 4 (2000-01): 35-51.) Reid and Berkeley disagreed over whether we directly perceive objects located outside of us in a surrounding space, commonly revealed by both vision and touch. Berkeley considered a successful account of erect vision to be crucial for deciding this dispute, at one point calling it ‘the principal point in the whole optic theory.’ Reid's critique of Berkeley's position on this topic is very brief, and appears to miss Berkeley's point. I argue that (...) there is more to Reid's response to Berkeley than at first meets the eye. Reid's rival account of erect vision draws on evidence that makes a compelling case for the position that we see the same space that we touch. (shrink)

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. (shrink)