Thomas Reid's Geometry of Visibles as Basis for a Theory of the Perspectival Character of Vision

• Applicant: Dr. Hannes Ole Matthiessen
• Subject Area: Theoretical Philosophy ; History of Philosophy
• Term: from 2015 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 275664513

• Final Report Year: 2023

Final Report Abstract

My aim is to show that Thomas Reid‘s geometry of visibles can support the theoretical framework to understand and conceptualize the perspectival content of (primarily visual) perception. Thomas Reid draws a distinction between the mediate objects of vision (ordinary things we see in our environment) and the immediate objects of vision, called visible figures (visibles, for short). The latter correspond, roughly, to those appearances painters attend to when they try to depict a scene: a coin may appear as an ellipse, a figure in the distance appears smaller than one nearby, etc. An object’s visible figure corresponds to the section of the visual field occupied by it. Thomas Reid’s (1764) Geometry of Visibles describes the geometrical properties of visible figures as identical to those of their projections on the inside of a sphere with the eye (and the point of projection) in its center. This implies that we are confronted, in ordinary vision, with non-euclidean figures. Besides this perspectival element, however, seeing also possesses a non-perspectival character: the coin that looks elliptical does evidently also still look round. This gives rise to the "puzzle of perspective": How can the coin appear round and elliptical, given that both are determinates of the determinable shape? A Reidean account of the relation between the two aspects of perception (the perspectival and the intrinsic) is best suited to solve the problem of perspective. For this, the 1. metaphysical, 2. epistemic and 3. phenomenal properties of visible figures as described by Thomas Reid, need to be taken into account: 1. While shape is an intrinsic property, visible figure is understood as a relational property. It really belongs to the object - that is, it is neither to be explained psychologically or physiologically - but it depends on a certain viewpoint. If, therefore, the ellipticality and the roundness of the coin are understood as properties of different metaphysical kinds, it is no longer puzzling that one coin may have them both. 2. Furthermore, Reid states a specific epistemic asymmetry between visible and real figures: the former serve as signs by which we perceive the latter. As in other semiotic contexts, our attention is typically drawn to the signified, not the sign. This is compatible with our ability to attend to the sign at will, when circumstances require it. This picture explains why both aspects are relevant in the perception of the coin, and it is no more puzzling why they both occur. 3. Finally, Reid makes a phenomenological point, a correlate of the epistemic asymmetry: Since we are normally concerned with the intrinsic properties and since attention to visible figure requires conscious effort, the two aspects rarely conflict with each other. Although it is correct to say that the coin looks round just as it is correct to say that it looks elliptical, these two facts do not constitute a contradiction, since they do not concur.

Publications

• Empirical Conditions for a Reidean Geometry of Visual Experience. Topoi, 35(2), 511-522.
  Matthiessen, Hannes Ole
  
• Introduction: The Geometry of the Visual Field—Early Modern and Contemporary Approaches. Topoi, 35(2), 461-463.
  Matthiessen, Hannes Ole
  
• Who Placed the Eye in the Center of a Sphere? Speculations about the Origins of Thomas Reid's Geometry of Visibles. Journal of Scottish Philosophy, 14(3), 231-251.
  Matthiessen, Hannes Ole
  
• “Berkeley and Reid on Projective vs. Phenomenal Visible Figures”, Vortrag auf der Tagung “From Love to The Infinite”, Berlin, Juli 2016
  Hannes Ole Matthiessen
  
• “About Temporal and Spatial Self-Location”, Vortrag auf dem DGPhil-Kongress, Berlin, September 2017
  Hannes Ole Matthiessen
  
• “Astronomy and Phenomenology in Thomas Reid – on the Incidental Influence of Science on Philosophy”, Vortrag auf der CSSP-Konferenz “Science in the Scottish Enlightenment”, Princeton, März 2017
  Hannes Ole Matthiessen
  
• “Reid's Geometry of Visibles – Phenomenology, Theory of Vision, or Theory of Perspectival Content?”, Vortrag auf der Tagung “Thomas Reid on Perception, Epistemology, and Metaphysics”, Köln, März/April 2017
  Hannes Ole Matthiessen
  
• „Reid on Apparent and Real Colours”, Vortrag auf dem Berlin-Hamburg-Workshop in Early Modern Philosophy, Hamburg, Juni 2019
  Hannes Ole Matthiessen
  
• A Reiding of Berkeley's Theory of Vision. Journal of Scottish Philosophy, 20(1), 19-40.
  Matthiessen, Hannes Ole