The following is a science fiction about consciousness in which I’ve twisted a few counterfactual knobs to make things tough for the materialist. In this attempted reductio, I assume physicalism is the case, and generate a putatively serious objection. It is the only line of thought that has recently given me serious worries as a neurophile, so I am curious what others think.
Imagine there exists an alien species that not only lacks concepts about subjective experience, but is altogether devoid of subjective experience. Perhaps they are insensate proposition-crunchers or implement an extremely plastic lookup table. They have come to Earth to study the brains of cats, a species that (unlike them) is conscious but (like them) has no conception of consciousness.
Note I realize this may ultimately be an incoherent scenario, but let’s go with it to examine the implications, if any, for the materialist. After all, if materialism can escape unscathed from a story custom-made to favor antimaterialism, that will bode poorly for many weaker species of antimaterialist arguments.
The aliens take a purely scientific approach to cats, using only neural and behavioral data (including “wide” facts about the cats’ environment) as the basis for their theories. They discover many higher-level properties of nervous systems by carefully studying phenomena that we associate with consciousness: anesthesia, dreaming, hallucinations (e.g., phantom limbs), perceptual illusions (e.g., binocular rivalry), and more general sensory and perceptual processes (e.g., sensory thresholds and attention).
Their research reveals two distinct modes of neural processing, a conspicuous division between (what we call) conscious and unconscious processes. The aliens refer to them as ‘smonscious’ and ‘unsmonscious’ processing modes, which they proceed to study exhaustively. Smonscious processes involve the neural construction of a low-capacity, highly integrated multimodal sensory representation of what is presently happening nearby. The second, unsmonscious, processing mode is extremely high capacity but lacks coherence and dense intercommunication among its constituent representations, though it includes a massive cortical memory store.
They also find that the two processes have quite different functional consequences within the ecology of the nervous system: there are clear differences in their interactions with episodic memory, decision making, attention, and working memory. Disrupting smonscious processing is devastating for any cat, so the aliens are never tempted to suggest that smonsciousness is an epiphenomenon.
Even though the aliens enjoy no conscious experiences, they develop their neuropsychological theory to the point where they can produce a thick phenomenological portrait of the cat’s world in real time. ‘Right now he is smonscious of the smell of a mouse nearby, but not that the dog barked, because he is not attending to auditory inputs.’ The contents of this polymodal ‘movie’ perfectly describe the conscious perceptual experiences of the cat.
In sum, the signatures of conscious versus unconscious neural processes are written starkly into the objective computational contours of the CNS. Metaphysically speaking, since experiences are brain processes of a certain sort, and the aliens have discovered said brain processes, they have ipso facto discovered and characterized conscious brains in objective terms. There is no additional property out there remaining for the aliens to discover, no new ingredient that must be added to their story to make it complete. Far from being only available “subjectively,” subjectivity itself is an objective feature of the brain that will be discovered by anyone that takes a dispassionate look
So far, the materialist in me is very happy. In Part II, this takes a bit of a U-turn.