Thomas Reid argued that the geometrical properties of visible figures equal the geometrical properties of their projections on the inside of a sphere centred around the eye. In recent scholarship there are only a few suggestions of which sources might have inspired Reid. I point to a widely ignored body of early eighteenth-century literature – introductions into projective geometry, the use of celestial globes and astronomy – in which the model of the eye in the centre of a sphere was (...) immensely popular. Moreover, I argue that Reid's account results naturally from some astronomical doctrines in conjunction with George Berkeley's theory of vision. (shrink)

Thomas Reid's Geometry of Visibles, according to which the geometrical properties of an object's perspectival appearance equal the geometrical properties of its projection on the inside of a sphere with the eye in its centre allows for two different interpretations. It may (1) be understood as a theory about phenomenal visual space – i.e. an account of how things appear to human observers from a certain point of view – or it may (2) be seen as a mathematical model of (...) viewpoint-relative but mind-independent relational properties of objects. This paper makes a systematic and a historical claim. I shall argue, first, that given certain features of the human visual system phenomenal visual space differs in several aspects from Reidean visual space. Secondly, I suggest that, since Reid was aware of some of these empirical facts, we should interpret Reid as endorsing the second interpretation of the Geometry of Visibles. (shrink)

George Berkeley argues that vision is a language of God, that the immediate objects of vision are arbitrary signs for tactile objects and that there is no necessary connection between what we see and what we touch. Thomas Reid, on the other hand, aims to establish a geometrical connection between visible and tactile figures. Consequently, although Reid and Berkeley's theories of vision share important elements, Reid explicitly rejects Berkeley's idea that visible figures are merely arbitrary signs for tangible bodies. But (...) is he right in doing so? I show that many passages in Berkeley's work on vision suggest that he acknowledges a geometrical connection between visibles and tangibles. So the opposition between the arbitrariness Berkeley defends and a geometrical connection cannot be as universal as Reid thinks. This paper seeks to offer a plausible reading of Berkeley's theory of vision in this regard and an explanation of why Reid interprets Berkeley differently. (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)

Defining actions in contradistinction to mere happenings runs into the problem of specifying the role of the agent and separating what the agent does from what they exploit or suffer. Traditionally these problems have been approached by starting with a simple act, such as an incidental movement, and considering causality, or by seeking to elucidate the connection between the act and the agent's intentions or reasons. It is suggested here that a promising approach is to shift attention from 'simple' movements (...) and start instead by exploring the general character of acquired skills. Balancing the body is one such skill and serves here as an exemplar. Some remarks made by Reid on balance are used in a Peircean framework for perception to suggest that, at least for humans, an action is always the performance of an acquired skill. Also, while action is constitutive of perception, bodily perception is the basis of action, providing in a feeling of ownership direct knowledge of an asymmetric opposition between the agent and the world. (shrink)