“You're not understanding, are you? The brain does the thinking. The meat.” 

“Thinking meat! You're asking me to believe in thinking meat!” 

“Yes, thinking meat! Conscious meat! Loving meat. Dreaming meat .

The meat is the whole deal! Are you getting the picture?” 

“Omigod. You're serious then. They're made out of meat.”1 

A few weeks ago, I attended a forum entitled “The Glorious Mysterious Brain,” a sold-out event featuring prominent speakers as well as the fascinating subject. On the podium were autism and animal rights advocate Prof. Temple Grandin, Harvard psychologist philosopher and author Steven Pinker, and cognitive scientist and popular Yale professor Paul Bloom.

The thoughtful and entertaining discussions ranged over a variety of subjects dealing with the brain; how it works, its evolution, even how something as ugly as a 3-pound meat loaf could produce thoughts of such complexity and beauty. Then, Prof. Bloom made an almost offhand comment that the Mind is simply the activity of the brain plain and simple. Descartes dualism dismissed. Nuthin' to see here folks, move along.

As a secular anesthesiologist, occasional patient, and survivor of the 1960s, I had always taken the materialistic basis of the mind so for granted that I never gave it much … uh … thought. We see it in our day-to-day practice. A little something IV, a few breaths of gas, and Mind is gone or significantly altered, made happy, sad, or crazy until the chemicals, redistributed and eliminated, allow its return. Mind is simply the physiochemical function of the brain; all the great works of mankind, even our emotions, merely reflect complex patterns of neurotransmitters crossing microscopic distances to produce the incredible variation in expression that we call thought.

Glands secrete, stomachs digests, brains mind.

Since, in this ontological reduction, thought is just the activity of subatomic particles basically opening or closing circuits, the comparison of brains to digital computers becomes inevitable. Many of us watched the quiz show Jeopardy as IBM's computer Watson handily defeated prior champions Brad Rutter and Ken Jennings. Watson had a huge database (contained incidentally in a space the size of 10 refrigerators) and was created for the express purpose of playing and winning Jeopardy; nevertheless, its participation, let alone its victory, forces the questions: does a digital computer think? Alternatively, is human thought just digital computation, no more no less?

And then there's the unsettling corollary: Are we then just digital meat puppets?

Humans have pondered the mind body problem as long as they have had minds and bodies. The modern version began when the aforementioned René Descartes opined that the only thing that is conclusively knowable is that one exists: cogito ergo sum . I think, therefore I exist. He posited dualism: a body and a mind interconnected by God through the pineal gland. Subsequent generations of philosophers continued to question and argue the subject. In the past 40 yr, philosophers, psychologists, and mathematicians popularized the Computational Theory of Mind (CTM), the details of which go far beyond the scope of this essay, but essentially state that cognition is computational and algorithmic.

Critiques of CTM are as complex as the theory itself and come down to the belief that there is some knowledge that cannot be simplified down to a digital algorithm. It's not all there is. Of particular interest to us as physicians is the idea put forth by Hubert Dreyfus in the 1970s that, while a novice must follow a sequenced set of rules to achieve a desired result, an expert somehow just knows  what to do in a given situation. Dreyfus' example was chess, but we can easily compare an uninitiated first-year resident attempting an intubation or nerve block with the efforts of his experienced attending. Unfortunately, IBM damaged that analogy by creating Deep Blue, a chess-playing computer that defeated world champion grand master Garry Kasparov.

So where have we come? If CTM is true and Mind is merely the activity of the brain, there are some exciting possibilities. Is it reasonable to believe that as Darwinian evolution of the human brain progresses, it will adapt new tricks, the stuff of science fiction, such as mind reading, teleportation, and other unimaginable abilities?

Similarly, as computers evolve, who knows into what they could develop? Perhaps we'll even see the marriage of human and silicone brains or at least a civil union. There is, of course, a more sinister possibility; quoting Ken Jennings: “I for one welcome our new computer overlords.”

On the other hand, perhaps CTM is not the final word, for we may not know what we don't yet know. Remember when the universe consisted of concentric spheres with the Earth at the center, or when the world was flat, the universe stable? Then there was gravity, relativity, quantum theory, expansion, dark matter, dark energy, etc. Paradigms keep shifting, and knowledge changes.

Unlike the other travelers in Oz, I didn't believe in spooks, but now begin to wonder … perhaps there really is a ghost in the machine.

“… since I am in the secure possession of leisure in a peaceable retirement, I will at length apply myself earnestly and freely to the general overthrow of all my former opinions.” 

Bisson T: They're made out of meat [short story]. Cited by: Pinker S. How the Mind Works. New York, WW Norton, 1997