One of the implicit, and sometimes explicit, objectives of modern neuroscience is to find neural correlates of subjective experience so that different qualities of that experience might be explained in detail by reference to the physical structure and processes of the brain. It is generally assumed that such explanations will make unnecessary or rule out any reference to conscious mental agents. This is the classic mind-brain reductivist program. We have chosen to challenge the optimism underlying such an approach in the context of sensory neurophysiology and sensory experience. Specifically, we ask if it is possible to explain the subjective differences among seeing, hearing, and feeling something by inspecting the structure and function of primary visual, auditory, and somesthetic cortex.

After reviewing the progress in localization of sensory functions over the past two centuries and examining some aspects of the structure and function of somesthetic, auditory, and visual cortex, we infer that one cannot explain the subjective differences between sensory modalities in terms of present day neuroscientific knowledge. Nor do present trends in research provide grounds for optimism.

At this point we turn to three philosophical theories to see what promise they hold of explaining these differences. A brief discussion of each – identity theory, functionalism, and eliminative materialism – suggests that none adequately accounts for the facts of the situation, and we tentatively conclude that some form of dualism is still a tenable hypothesis.