Defence of a Reasonable Individualism

Abstract

The purpose of this paper is to defend the thesis that David Marr's (1982) computational theory of vision is individualistic. I shall not be much concerned with general arguments for or against the thesis.2 Rather I shall focus on its consequences. In particular, I want to consider what kinds of visual contents an individualist can countenance. Call content that supervenes locally on the subject content. Then the question is: what are narrow visual contents? In Matthews (1988) and Segal (1989) we find a suggestion about an answer to this question. I shall be elaborating and defending this suggestion. Many philosophers, some of them individualists, believe that narrow content must be-how should I put it?-weird and wonderful and radically unlike the everyday contents of folk psychological states that we are used to.3 I want to argue that, at least in the particular case of the computational theory of vision, narrow content is really quite mundane. If vision is anything to go by, then we should expect similar results in other areas.4 This conclusion might detract from the apparently exotic nature of individualism, but it will enhance its plausibility. The reason for the restriction to Marr's theory5 is that I want to keep the discussion focussed on a real scientific theory of a real phenomenon in the real world. That way philosophy is informed of and constrained by the facts, and there is hope of advance. For the record, I do think that individualism is true in general of scientific psychology and I think that many (but not all) of the considerations that apply to Marr's theory apply across the board. However both of these claims require extended discussion that I shall not provide here. The suggestion about narrow content offered by Matthews and myself arises in response to Burge style putatively anti-individualistic Twin Earth cases for