Content, computation, and individualism in vision theory
Since Marr's theory concerns visual states, it is individualistic, presumably, if it taxonomizes visual states without essential reference to the environment of the subject. I will not attempt to settle here whether or not Marr's theory is individualistic in this sense. I will argue, however, that Egan's reasons for thinking that Marr's theory is individualistic rest on a mistaken assessment of Marr's theory. Egan may be right that Morton's (1993) criticisms of her view miss their mark, but that provides her with no support for an individualistic interpretation of Marr's theory. Marr's theory is a computational theory, and computational theories, Egan claims, are concerned only with an articulation of the mechanisms of computation (see, e.g., Egan 1992: 445). These mechanisms operate independently of any semantic or intentional properties, so a theory of the computational mechanisms of the visual system will have no use for any appeals to contents. She argues that all descriptions of computations in the theory can be given formal characterizations; descriptions in terms of contents are therefore superfluous (see Egan 1992: 453-55).