In a recent post, I offered a non-causal dualist theory of sensory awareness on which when I see a red cube, there is a state rb of my brain representing the red cube, and a relation V of perception between rb and my soul, which relation is external to the soul. As a result, there need be no intrinsic difference between my soul when I am perceiving red cube and my soul when I am not perceiving a red cube.
I want to make a few more notes on this theory, for it seems to me that it is worth taking seriously.
1. This theory is very close to Aquinas’. Aquinas thought that sensory awareness was constituted by the reception of sensory data (“phantasms”) by sense organs. The sense organs, and not the soul, are modified by the sensory awareness. Of course, it was crucial to this that the sense organs be informed by the form of the animal, and the form of an animal is the soul. So we have a similar structure: there is a relation of the soul and the sense organs, and the sense organs are then modified by the sensory data. If we neglect the difference between the brain in my theory and the sense organs in Aquinas’s, then Aquinas’s theory is just an expansion on my theory. The state rb is the state of the sense organs having their sensory data, and my external relation V of perception on Aquinas’s view is simply constituted by a pair of relations on Aquinas’s: the informing relation of the soul to the organ, and the sensory-data-possession relation between the organ and its sensory data.
Thus, the main difference between my theory and Aquinas’s is that I replace the sensory organs with parts of the brain. And there is good reason to think that if Aquinas had the empirical data we do, he would think of the phantasms as in the brain rather than in the eyes, ears, etc. For we have good reason to think direct neural stimulation of the visual center of the brain could produce the same visual experience as gazing upon a red cube. Thus, the only difference between Aquinas and the theory—apart from Aquinas offering more detail on the relation V—is that on the theory, the sensory organs in Thomas’s sense are all inside the skull.
2. What we should say about qualia on this theory? The analogue to the visual quale of my perceiving a red cube on this theory consists of V and rb. That’s a pair of things rather than one thing. One of these two things, the brain state rb, is physical, but the other thing, the relation V, is a non-physical relation between a non-physical thing, the soul and a brain state rb. Thus qualia are partly non-physical and partly physical.
3. It seems the theory contradicts the knowledge argument. Consider the brain state rb representing a red cube and the brain state gb representing a green cube. It seems that on the basis of seeing a green cube, I can get to know the relation V obtaining between my soul and gb. And on the basis of neuroscience, I can get to know rb. Thus, without ever seeing anything red, it seems I can know what it’s like to see red.
I am not strongly attached to the knowledge argument in its standard form. I kind of like the radical variant on which a never conscious person could never get to know what consciousness is like. And that variant fits with the theory, since a never conscious person has never experienced the relation V. (You might say: A never conscious person couldn’t know anything. I think it is a mistake to require consciousness for knowledge. First, one can have non-occurrent knowledge without consciousness—I know my multiplication tables even when asleep. Second, the unconscious vampires in Watts’ Blindsight clearly have knowledge.)
That said, I do not think it is obvious that just by knowing what the ingredients are like one knows what the whole is like. Thus, knowing what rb and V are like may not be enough to know what it is like to have one’s soul stand in V to rb. (Compare: Alice knows what it is like to be married to Bob, and she knows Carl, but it doesn’t follow that she knows what it is like to be married to Carl.)
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