Representational Content and the Science of Vision
Ritchie, John Brendan Welsh
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The general topic of my thesis is how vision science explains what we see, and how we see it. There are two themes often found in the explanations of vision science that I focus on. The first is the Distal Object Thesis: the internal representations that underlie object vision represent properties of entities in the distal world. The second is the Transformational Thesis: the function of the vision system is to transform information that is latent in the retinal image into a representational format that makes it available for use by further perceptual or cognitive systems. The ultimate aim of my project is to show that these two themes are in tension, and to suggest how the tension may be resolved. The tension between these themes is, I argue, a result of their conflicting implications regarding the role of representational content (what a representation is ``about") in the explanations of vision science. On the one hand, the Distal Object Thesis entails that the internal representations that underlie object vision qualify as a form of mental representation, and reflect a sense in which visual perception is indeed ``objective". Furthermore, I argue at length that a commitment to the Distal Object Thesis (and its consequences) is well-founded: mental representations are indeed an indispensable posit for explanations of aspects of object vision. On the other hand, the Transformational Thesis rests on the presupposition that the content of the internal representations in the visual system are fixed by a causally reliable, information carrying relation. The tension arises because carrying information is insufficient for fixing the content of mental representations. Thus the explanations of object vision that assume the Transformational Thesis, but require a commitment the Distal Object Thesis, are seemingly inadequate. Fortunately, some philosophical theories of intentional content, or the ``aboutness" of mental representations, offer some strategies for reconciling these two themes in the explanations of vision science.