Content Individuation in Marr's theory of vision

The debate concerning the individuating role of the external environment in propositional content has turned to Marr's (1982) Computational theory of vision for either verification or disproof. Although not all the relevant arguments concerning the determining role of environmental constraints that Marr invokes in his visual account may succeed, the paper argues that Marr divides his computational explanation into two parts, the information processing "what" and the constraint introducing "why" aspect. It is the second part where separate claims concerning the necessity and sufficiency of constraints are advocated, and initiate a Specific Computational process. The above explanation becomes subordinate to a conception of inference that closely resembles deduction.