Thomas Reid claims to have learned of Idomenians, “an order of beings” in “sublunary regions” whose visual system is very much like ours except that they could detect only the direction of rays reaching their eyes, not the distance of origin. The properties of Idomenian vision are here examined in the light of the physiological optics of Reid’s time and of the scientific developments that have since augmented our knowledge of the discipline.

When we look at a tree, two images of it are formed, one on each of our retinas. Why, then, asks the child or the philosopher, do we not see two trees?1 Thomas Reid offers an answer to this question in the section of his Inquiry into the Human Mind entitled ‘Of seeing objects single with two eyes’. The principles he invokes in his answer serve at the same time to explain why we do occasionally see objects double. In Part (...) I of this essay, I examine the principles Reid uses to explain single and double vision. This part is mostly an exercise in the history of cognitive science, but it raises questions of interest to philosophers along the way. In Part II, I turn to a hard-core philosophical problem raised by double vision, namely, whether double vision constitutes an objection to the direct realist theory of perception, which was one of Reid's main philosophical purposes to promote. (shrink)

ABSTRACT:I reflect critically on the early modern philosophical canon in light of the entrenchment and homogeneity of the lineup of seven core figures: Descartes, Spinoza, Leibniz, Locke, Berkeley, Hume, and Kant. After distinguishing three elements of a philosophical canon—a causal story, a set of core philosophical questions, and a set of distinctively philosophical works—I argue that recent efforts contextualizing the history of philosophy within the history of science subtly shift the central philosophical questions and allow for a greater range of (...) figures to be philosophically central. However, the history of science is but one context in which to situate philosophical works. Looking at the historical context of seventeenth-century philosophy of mind, one that weaves together questions of consciousness, rationality, and education, does more than shift the central questions—it brings new ones to light. It also shows that a range of genres can be properly philosophical and seamlessly diversifies the central philosophers of the period. (shrink)

According to a certain kind of naïve or folk understanding of physical matter, everyday ‘solid’ objects are composed of a homogeneous, gap-less substance, with sharply defined boundaries, which wholly fills the space they occupy. A further claim is that our perceptual experience of the environment represents or indicates that the objects around us conform to this sort of conception of physical matter. Were this further claim correct, it would mean that the way that the world appears to us in experience (...) conflicts with the deliverances of our best current scientific theories in the following respect: perceptual experience would be intrinsically misleading concerning the structure of physical matter. I argue against this further claim. Experience in itself is not committed to, nor does it provide evidence for, any such conception of the nature of physical matter. The naïve/folk conception of matter in question cannot simply be ‘read-off’ from perceptual appearances. (shrink)

There are issues in Reid scholarship as well as the primary texts that seem to suggest that Reid is not a direct realist about visual perception. In this paper, I examine two key issues ? colour perception and visible figure ? and attempt to defend the direct realism of Reid's theory through an interpretation of ?directness? as well as what Reid calls ?acquired perception?, which is ?mediate? in that it requires prior perception of signs, but nonetheless constitutes direct perception.

The reports of individuals who have had their vision restored after a long period of blindness suggest that, immediately after regaining their vision, such individuals are not able to recognize shapes by vision alone. It is often assumed that the empirical literature on sight restoration tells us something important about the relationship between visual and tactile representations of shape. However, I maintain that, immediately after having their sight restored, at least some newly sighted individuals undergo visual experiences that instantiate basic (...) shape phenomenology but which do not present (that is, neither represent nor involve acquaintance with) the corresponding shape properties. Consequently, the empirical literature on sight restoration tells us something important about the role that perceptual phenomenology plays in our perceptual awareness of an object’s properties—it tells us that the properties presented by perceptual experiences are not determined by or “built into” perceptual phenomenology. In addition, I maintain that the evidence concerning sight restoration suggests an alternative theory concerning the role that sensory phenomenology plays in our perceptual awareness of an object’s properties. Specifically, it suggests that, while not inherently representational, sensory phenomenal properties can serve as vehicles for the representation of an object’s properties. (shrink)

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 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)

Some recently popular accounts of perception account for the phenomenal character of perceptual experience in terms of the qualities of objects. My concern in this paper is with naturalistic versions of such a phenomenal externalist view. Focusing on visual spatial perception, I argue that naturalistic phenomenal externalism conflicts with a number of scientific facts about the geometrical characteristics of visual spatial experience.

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)

In issue 6.1 of the Journal of Scottish Philosophy, James Van Cleve describes Thomas Reid's understanding of double vision and then presents a challenge to his direct realism found in works of David Hume based on double vision. The challenge is as follows: When we press one eye with a finger, we immediately perceive all the objects to become double, and one half of them to be remov'd from their common and natural position. But as we do not attribute a (...) continu'd existence to both these perceptions, and as they are both of the same nature, we clearly perceive, that all our perceptions [i.e., all the things we perceive] are dependent on our organs, and the disposition of our nerves and animal spirits. (THN: 210–211). (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)

Drawing on work done by Helmholtz, I argue that Reid was in no position to infer that objects appear as if projected on the inner surface of a sphere, or that they have the geometric properties of such projections even though they do not look concave towards the eye. A careful consideration of the phenomena of visual experience, as further illuminated by the practice of visual artists, should have led him to conclude that the sides of visible appearances either look (...) straight, in which case their angles appear to approximate Euclidean measures, or their angles do not appear to approximate Euclidean measures for straight line figures, in which case their sides do not look straight. (shrink)

According to Minkoswki, Einstein's special theory of relativity reveals that ‘space by itself, and time by itself are doomed to fade away into mere shadows’. But perceptual experience represents objects as instantiating shapes like squareness — properties of ‘space by itself’. Thus, STR seems to threaten the veridicality of shape experience. In response to this worry, some have argued that we should analyze the contents of our spatial experiences on the model of traditional secondary qualities. On this picture—defended in recent (...) work by Chalmers —an experience of squareness just represents whatever property usually causes such experiences. This view salvages the veridicality of shape experience, but leaves the nature of the properties we perceive outside our ken. I argue that such a move is unwarranted: STR is compatible with the idea that shape experience acquaints us with the spatial character of our world. In defending this claim, I propose a view on which shape experience presents familiar Euclidean spatial properties veridically, while implicitly representing those properties as instantiated in a particular manner — namely, relative to our own frame of reference. (shrink)

Thomas Reid’s epistemological ambitions are decisively at the center of his work. However, if we take such ambitions to be the whole story, we are apt to overlook the theory of mind that Reid develops and deploys against the theory of ideas. Reid’s philosophy of mind is sophisticated and strikingly contemporary, and has, until recently, been lost in the shadow of his other philosophical accomplishments. Here I survey some aspects of Reid’s theory of mind that I find most interesting. I (...) examine whether Reid is a mysterian about the mind, whether Reid has a direct realist theory of perception, and whether Reid has a higher-order, or “inner-sense,” view of consciousness. Along the way I will mention portions of the secondary literature that examine these aspects and point out whether and to what degree I part ways with the interpretations present in the literature. (shrink)

A coin rotating back in depth in some sense presents a changing, elliptical shape. How are we to understand such (in this case) ‘appearances of ellipticality’? How is the experiential sense of such shifting shape appearances related to the experiential sense of enduring shape definitive of perceived shape constancy? Is the experiential recovery of surface shape based on the prior (perhaps more fundamental) recovery of point or element 3D spatial locations?—or is the perception of shape a largely independent perceptual achievement? (...) Do we gain access to enduring shape properties by first detecting and working from ‘shape appearances’? These are some of the topics taken up in this paper. (shrink)

The controversy over the interpretative issue—is Thomas Reid a perceptual direct realist?—has recently had channelled into it a host of imaginative ideas about what direct perception truly means. Paradoxically enough, it is the apparent contradiction at the heart of his view of perception which keeps teasing us to review our concepts: time and again, Reid stresses that the very idea of any mental intermediaries implies scepticism, yet, nevertheless insists that sensations are signs of objects. But if sensory signs are not (...) mental intermediaries, what are they? Hasn't Reid merely swapped the common ‘sensation’ for the notorious ‘idea’, ending up with indirect realism?1 Current imaginative strategies answer negatively: Reid's sensory sign does not contradict direct perception, and those who think otherwise merely fail to understand what it means. (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)

In a recent article on Reid’s theory of single and double vision, James Van Cleve considers an argument against direct realism presented by Hume. Hume argues for the mind-dependent nature of the objects of our perception from the phenomenon of double vision. Reid does not address this particular argument, but Van Cleve considers possible answers Reid might have given to Hume. He finds fault with all these answers. Against Van Cleve, I argue that both appearances in double vision could be (...) considered visible figures of the object, and show how this solution might preserve Reid’s direct realism. However, this solution is not compatible with the single appearance of an object predicted by Reid’s theory of single and double vision. This consequence will appear evident once we consider the critique of Reid’s theory of single and double vision formulated by William Charles Wells (1757-1817). Wells argues that Reid’s theory is either incomplete or incompatible with other claims made by Reid. It is incomplete since it fails to specify the unique direction in which we the object in single vision; if it not incomplete and is compatible with the law of monocular direction given by Reid, then it is incompatible with Reid’s claim that we do not perceive immediately distance by sight. (shrink)