The Dennes Room

Event Detail

Wed Dec 9, 2015
Howison Library, 4–6 PM
Graduate Research Colloquium
Peter Epstein (UC Berkeley)
Shape Perception in a Relativistic Universe

Motivated in part by considerations from Einstein’s theory of relativity, some in the recent literature on perception have argued that we should analyze the contents of our spatial experiences on the model of traditional secondary qualities. According to this kind of “placeholder” view, an experience of a spatial property like squareness just represents whatever property it is that usually causes such experiences. On the “presentationalist” view, by contrast, experiences of squareness are more committal: their content explicitly specifies a particular, determinate spatial property, rather than merely providing an open-ended description (through which some determinate property might be picked out). I argue that the placeholder account of shape perception is misguided because it ignores the way in which the concepts that feature in our perceptions of shape also feature in our a priori geometrical reasoning. Perceptions of squareness attribute the determinate property of Euclidean squareness to the objects we perceive. In defending this claim, I address a recent argument by Chalmers that attempts to support the placeholder view with a relativistic analogue of Putnam’s Twin Earth. After showing that Chalmers’s argument fails— because the relativity of spatial properties revealed by Einstein’s theory does not depend on the kind of rigid reference-fixing on which Putnam’s case turns—I propose a way of reconciling the Einsteinian picture of our physical universe with the natural thought that the shape properties that feature in our spatial perception are the very same properties about which we reason when doing a priori geometrical proof.