I am currently reading David J. Chalmers’ 1996 book The Conscious Mind: In Search of a Fundamental Theory which claims that, due to consciousness not being logically supervenient, there is no reductive explanation for consciousness. Thus Chalmers concludes that consciousness must be explained through a dualist paradigm. I have some issues with the argument.

Logical supervienience means that the higher-level concepts logically follow from the lower-level facts. For instance, the concept of wetness with water is explainable by the way the water molecules move when in its liquid phase – given just the facts about the microphysical state of the liquid water molecules, and an understanding of what wetness is, one could logically infer that liquid water is wet.

Or, put more abstractly:

A set of properties A supervenes upon another set B just in case no two things can differ with respect to A-properties without also differing with respect to their B-properties.

Chalmers claims that consciousness is not logically supervenient. Given the microphysical state of the brain while seeing green, one could never logically infer the quale of red. Chalmers argues that one can conceive of a possible world that is exactly like ours in every way, except that for every person – including your own counterpart – there is no first person experience. Or, as Thomas Nagel might put it, there is nothing that it is like to be the inhabitants of this zombie universe. Consciousness, the A-property, is different without a different in brain states, the B-properties.

A possible problem with this that Chalmers himself attempts to refute is that the inhabitants of the possible zombie world would still be making the same judgments about conscious experience that we do – appreciating music, being disgusted by violent images, wondering how consciousness works – even though they have no consciousness. Chalmers says that this would be possible because the zombies, though lacking some internal conscious sensation, could still perceive music and images, cognitively process the data, and make verbal reports, since these psychological states can all be explained physically. However, Chalmers argues, none of these psychological states are necessarily accompanied by conscious experience.

I would argue that the qualia of our experience is, in fact, the processing of data from our perceptions. For instance, the color red itself is data that, to us, is represented as the red quale. The red data represents the physical perception. Mathematically, red might be represented as a vector in some n-dimensional space, with the dimensions representing things like transparency, intensity, etc. The vectors could be multiplied by other vectors representing other primary colors in order to obtain color mixtures.

However, instead of red being represented as mathematical vectors, which are themselves an abstract entity, red is instead represented as the quale red. Since there is no Cartesian theater, consciousness exists as the data – the qualia – during processing in the brain. Consciousness, like math, is an abstract epiphenomenal representation that arises from the processing of information. Thus, there can be no information processing without the accompanying conscious experience.

My argument against this conception of consciousness, then, is that consciousness does, in fact, logically supervene on the physical world. The sort of data processing occurring in our brains is necessarily done in the form of qualia, rather than mathematics or some other possible data processing medium. A computer is not conscious because it does its data processing using mathematics. However, to say that our brain processes can occur without the accompanying consciousness would be like saying my computer could be doing the exact same thing it is doing now without the accompanying mathematics – math is the abstract medium in which computer processing occurs and consciousness is the abstract medium in which brain processing occurs.

(Under this conception, I think we would be forced to concede that no two individuals experience that exact same qualia in their conscious experience. Every person makes different associations and imbues different emotional salience to the color red, for instance. Mathematically speaking, this would mean that the vector for red data would have a different orientation in the n-dimensional space.)

Thus, there is no possible world where zombie versions of ourselves, living the exact same lives but with no conscious experience, just as there is no possible world where all our computers function exactly the same but without doing mathematics.

Consciousness, in my conception, naturally and necessarily arose via evolution. Consciousness is the medium for processing perceptual (and in humans, at the very least, conceptual) information that was selected for by evolution. The zombie world would never even conceive of conscious experience in the same way that we, in our real world, cannot conceive of a wholly new color or some extra sense beyond what we already possess (something that isn’t just seeing or hearing more than what normal people can, but some sensory modality that is completely novel and not akin to what we already possess). Thus, there could be no zombie world where the inhabitants make judgments about consciousness, just as we do not make judgments about colors we can’t conceive of or perceptual data taken in by some completely novel sensory modality.