This passage from E.O. Wilson’s book Consilience piqued my interest:
Without the stimulus and guidance of emotion, rational thought slows and disintegrates. The rational mind does not float about the irrational; it cannot free itself to engage in pure reason. There are pure theorems in mathematics but no pure thoughts that discover them. In the brain-in-the-vat fantasy of neurobiological theory and science fiction, the organ in its nutrient bath has been detached from the impediments of the body and liberated to explore the inner universe of the mind. But that is not what would ensure in reality. All the evidence from the brain sciences points in the opposite direction, to a waiting coffin-bound hell of the wakened dead, where the remembered and imagined world decays until chaos mercifully grants oblivion.
Wilson does a good job synthesizing consciousness studies and taking a stab at describing the physical and psychological bases of the mind. This paragraph, though, stuck out like a sore thumb from the chapter and book, in part because he calls back to the midcentury notion of disembodied brains controlling the world and in part because he waxes poetic in his dismissal of that idea. (Wish I could write so well ….) I vaguely remember reading Donovan’s Brain back in my youth. There is even a Wikipedia entry for the novel, which was made into a movie at least twice, one with Nancy Reagan. More familiar to the TV generation is the same basic story idea that found its way into a Star Trek episode called “Spock’s Brain.” The terseness of both titles is a humorous curiosity.
The larger point, I guess, is that the brain’s various routines that operate in parallel to construct consciousness are inseverable from sensory inputs from the body and from the emotional context used to create narrative. As such, it’s important to recognize that there is no divine Truth or Objectivity out there beyond our grasp or perception, even though we may sometimes hope for such things. (We adopt a posture of objectivity to reduce the distortions of emotion and irrational thinking, but that’s not the same thing.) There is a physical reality that is somewhat discontinuous with our perception of everyday “reality.” Such limitations are built into our physiology, just like we lack the eagle’s acute visual perception or the dog’s acute olfactory sensation.
If the brain can’t exist without the body, how much of the body can be missing before the brain fails to function? It’s a strange question, and the answer is quite a lot. None of the extremities are essential, nor are most of the sensory parts (ears, eyes, tongue, nose) — at least separately. Few examples exist of individuals deprived of their senses, but Helen Keller is one obvious example. Her sightlessness and deafness (not from birth but from an illness at nineteen months) delayed her cognitive development until she broke through the symbolic barrier and developed language later in childhood. Over 70 cases of deafblindness are known, some congenital and others acquired. If an example exists of a fully developed mind later deprived of all sensory experience, it would be curious to know how long a person stays rational before the descent into madness begins.