Consciousness and Cognition 10, 117–124 (2001) doi:10.1006/ccog.2000.0481, available online at http://www.idealibrary.com on What Colors? Whose Colors? Mohan Matthen Department of Philosophy, The University of British Columbia, Vancouver, British Columbia V6T 121 Canada E-mail: mohan.matthen@ubc.ca Scientists often complain that philosophers do not know what they are talking about. Unfortunately, this is sometimes true (though just as often the truth is that scientists cannot fathom what philosophers are talking about). Until recently, philoso- phers took it to be obvious that the visual field corresponds closely to the pattern of electromagnetic energy incident upon the retina, the retinal ‘‘image,’’ as it is some- times called. They thought that everything we see—surfaces, solids, movements, faces, and so on—is decomposable into points of incident energy in much the way that Monet’s paintings of the Cathedral at Rouen decompose into small colored patches. They also believed that the visible properties of these points of color corre- sponded closely to the retinal ‘‘image.’’ (At the very least, philosophers wrote and spoke as if this assumption of correspondence was harmless.) Thanks to ‘‘visual science’’ we now know that these assumptions are false: The perception of a face is not decomposable into perceptions of color-points, and perceived color does not correspond to the physical characteristics of electromagnetic waves. If philosophers do not get their facts straight, their theories will be useless or worse: apriorism is not an excuse for ignorance. Fortunately, many have come to recognize this (some only slowly). It is not only philosophers who do not know what they are talking about when they venture outside their area of expertise. Often ‘‘visual scientists’’ do not either. Some visual scientists are apparently apt to say things like: ‘‘Color is a property of the brain,’’ or ‘‘Color is a neural process,’’ or ‘‘Color is a mental event.’’ No doubt these jeux d’esprit are not meant to be taken literally or subjected to minute philo- sophical analysis. Perhaps they are meant only to express the irritation that visual scientists feel at the a priori pronouncements of philosophers. However that might be, such statements are so far off the mark, metaphysically speaking, that it is ex- tremely difficult to determine what (if any) serious point they contain. Peter Ross is right to protest that hidden behind some of the more exuberant utterances of visual scientists lie unexamined philosophical assumptions. I hope that if we philosophers can manage to inform ourselves of at least a little visual science, and if we express ourselves clearly and logically, we can bring some degree of metaphysical order to the discourse of that science. Commentary on P. W. Ross (2001). The location problem for color subjectivism. Consciousness and Cognition, 10, 42–58. Address correspondence and reprint requests to Mohan Matthen, Department of Philosophy, The Uni- versity of British Columbia, Vancouver, British Columbia, V6T 121 Canada. 117 1053-8100/01 $35.00 Copyright  2001 by Academic Press All rights of reproduction in any form reserved.