But what's really going on here? We aren't visualizing a literal cat — that is, there isn't a physical cat lodged in our brains. The cat is some kind of mental representation of something that exists 'out there'. It doesn't seem to make any sense to say it's physical. So, it's an abstraction. But what is that? Semantics, metaphor, abstraction — what exactly are these things? They can't be physical — you can't open up a human brain and find "semantics". But if they're non-physical, what does that mean?
Renee Descartes attempted to capture the mystery of the mind in the Sixth Meditation:
[T]here is a great difference between the mind and the body, inasmuch as the body is by its very nature always divisible, while the mind is utterly indivisible. For when I consider the mind, or myself in so far as I am merely a thinking thing, I am unable to distinguish any parts within myself; I understand myself to be something quite single and complete….By contrast, there is no corporeal or extended thing that I can think of which in my thought I cannot easily divide into parts; and this very fact makes me understand that it is divisible. This one argument would be enough to show me that the mind is completely different from the body…. (AT VII 86-87: CSM II 59).Descartes is arguing here that the mind cannot be divided into parts, like a body can. You can't split the self in half, and have two selves (or can you?) the way you can split a body in two. Clearly, Descartes reasons, the mind cannot be a physical thing like the body.
Another way to think about this is the distinction between the quantitative and the qualitative. The phenomenological experience of consciousness is fundamentally qualitative — color, texture, taste, sound, emotion; while the external physical world is fundamentally quantitative — measured in mathematical descriptions of shape, size, weight, physical law, etc. This would appear to have two profound implications: one, that the body (and with it, the physical brain) cannot be the same kind of thing as the mind; and two, that qualitative descriptions of the world — including the entire enterprise of science — are fundamentally limited by their inability to account for qualia.
So when I'm thinking about the cat, I'm not thinking about a cat that is measurable. The cat in my mind has no definitive shape, size, weight, or anatomical structure. It is composed of nothing and, like the self, is indivisible. Indeed, this cat completely eludes any kind of quantitative analysis at all — it is an abstraction. And yet while I of course know that the cat isn't literally in my mind, the qualitative experience is nonetheless fully real to me. My subjective experience of self, of semantic meaning, of abstract thought — all of these things are as much a part of my veridical experience as anything I can touch, taste, see, hear, or smell.
Catholic theologian Ed Feser summarizes the dilemma well:
Thoughts and the like possess inherent meaning or intentionality; brain processes, like ink marks, sound waves, and the like, are utterly devoid of any inherent meaning or intentionality; so thoughts and the like cannot possibly be identified with brain processes.I'll spend a good deal of time later in this series arguing that this position is wholly undermined and indeed demonstrably false given the findings of the modern theory of embodied cognition. But the problem facing a scientific, empirical understanding of the mind should be clear: science purportedly measures only the physical and quantitative; but the mind is defined by qualia like metaphor, abstraction, and semantic meaning. As we can see from the forcefulness of Feser's statement, dualists generally take dilemmas like these to be in principle insurmountable by monist theories of mind, and in order to show why such a view is misguided it'll be necessary to re-examine what things like metaphor, semantics, and abstraction really are in the first place. But dualist theories of mind raise a litany of problems on their own, and recognizing their deficiencies will ultimately help us see the strength of what dualists claim is impossible: a scientific understanding of the mind.
Next: Problems with Dualsim