Abstract

Can qualia be analyzed by theories that contain only non-qualitative terms? A host of philosophers including Block, Levine, Nagel, and Jackson have argued that, in principle, they cannot. And yet psychophysicists have advanced explanations that seem to account for sensory appearances in terms of the operations of nervous systems. Here are some examples: Mach bands, the assimilation effect, and the Hermann grid illusion all have to do with the look of things, and all are routinely thought to be a consequence of the structure of visual receptive fields. Simultaneous contrast and auditory tuning—both perceptual effects—are lateral inhibition phenomena. That television sets with only three phosphor colors can replicate natural scenes with thousands of distinguishable colors is due to our eyes having just three photopigments. The difference between a three-type receptoral configuration and an array of thousands of receptors with distinct responses accounts for the fact that hues form a closed loop in color space, whereas there are no closed pitch loops in auditory space.