
Logic and Philosophy of Science Group Talk (Will Davies, Oxford)
Thursday March 27, 2025, 3:00 pm - 5:00 pm
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The Logic and Philosophy of Science Group is pleased to welcome as guest speaker Will Davies, an associate professor and Gabriele Taylor fellow in Philosophy at St. Anne’s College, University of Oxford. Dr. Davies’s research interests lie in the philosophy of mind – including philosophy of psychology and psychiatry – and related areas of epistemology and metaphysics. His work examines colour constancy, social mechanisms in psychiatry, and biosychosocial psychiatry.
Talk Title
Seen the Light? The Nature, Spatial Structure, and Perception of Illumination
Talk Abstract
In viewing a city scene, one sees many material objects of varying sizes, shapes, and colours. One sees light-emitting objects, like billboards and street lights. Plausibly, one also sees the scene as illuminated in certain ways: shadowed here, brightly lit there; a swathe of gloom here, a shaft of sunlight there; and so forth. In perceptual theory, however, the orthodoxy is that we do not strictly see illumination; we see only illuminated objects, or objects with such-and-such illumination-dependent properties. This scepticism is linked to the assumption that illumination is simply light. For physics tells us that light is photons or electromagnetic waves, and these are not candidate objects of perception. Photons are massless, immaterial parts of the quantum world. Streams of photons lack surfaces and are not organised into parts. Photons propagate effectively instantaneously, hence are not trackable. Experimentalists ‘observe’ photons, only by detecting their effects on matter. Contrary to the assumption, however, illumination and light are nonidentical: they are different kinds of stuff. Illumination is a macroscopic part of natural environments, constituted by accretions of light reverberating between earth, sky, and everything in between. These reverberations produce stable, coarse-scale systems of aggregate light flow. These systems are informationally rich and ecologically significant, being structured by matter and light sources within the environment. Drawing on Gershun’s (1939) geometrical optics and Gibson’s (1986) ecological optics, I develop an account of the nature and spatial structure of illumination. I use this account to characterise familiar features of illumination, such as its flow through space and across surfaces; its co-location or interpenetration with material objects; and its often amorphous or unbounded character. I argue that the account meshes with the visual phenomenology of illumination, and that this mesh is substantiated by models in computational vision science. Contrary to popular belief, then, illumination deserves a place among the ‘ordinary’ objects of visual perception.
About the Logic and Philosophy of Science Group
One of six departmental Research Interest Groups, the Logic and Philosophy of Science Group hosts talks on logic, general philosophy of science, and philosophy of the particular sciences, as well as talks in allied areas such as formal epistemology, decision theory, and the metaphysics of science.
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