Abstract

The thesis defends the view that a purely propositional theory of human cognition cannot provide an explanatorily adequate account of visual imagery. It is argued that the representational properties of images are derived from cognitive structures and processes which cannot be characterized propositionally. I provide evidence from the psychological literature which supports the view that visual images differ from propositional representations in important respects. A model of visual imagery is then presented which accounts for experimental evidence and which has certain advantages over a purely propositional model. ;In Chapter I I examine the issue of psychological explanation and support the view that the simplest psychological theory may not be explanatorily adequate. ;In Chapter II the issue of representation is investigated, and a theory is presented which is later used to help characterize imagistic and propositional representations. ;There is no standard characterization of either images or propositions in the psychological literature, and even in philosophy there is no standard conception of what 'proposition' refers to. I rectify this state of affairs in Chapter III by providing what seem to be the important distinguishing features of imagistic representations and propositional representations. ;In Chapter IV I present and discuss psychological experiments cited by both imagists and propositionalists. Experimental results seem to indicate that imagery is not epiphenomenal, but rather functional, in that its employment in certain tasks affects behavior. ;In Chapter V I argue that a purely propositional account of imagery cannot account for the experimental results, and that such a theory is not able to provide the sort of account that many theorists require of an explanatory theory of psychology