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Why the Mind Can’t Just Be the Brain

Thinking it through carefully, the idea doesn't even make sense

Philosopher Roger Scruton (1944–2020) defined neuroscience thus (I paraphrase): Neuroscience is a huge collection of answers with no memory of the questions.

Over the past century, neuroscientists have amassed vast libraries of data. But their interpretation of their data on the mind-brain question shows no meaningful understanding of the genuine questions their research is tasked to answer. These questions are ancient:

  • What is the relationship between the soul (or mind) and the body (or brain)?
  • How is it that matter can think?
  • How is it that third-person stuff gives rise to first-person experience?

Answers to such questions from the neuroscience community show little evidence of the profound and subtle nature of the questions. Thus, neuroscientists provide answers to questions they seem to have forgotten, if they ever understood them at all.

An uncommonly clear example of this amnesia is a recent post by Dr. Steven Novella (pictured), a neurologist from Yale. Dr. Novella and I have debated the mind-brain question for years—he has taken the materialist view; I take the dualist view. In this recent post, he accuses dualists of (more or less) believing in brain fairies. He compares mind-brain dualism to belief in liver fairies:

…what if there were [scientists] who claimed that, in actual fact, some of what we think of as liver function is actually a manifestation of liver fairies. These are mystical entities that live in the liver. They are invisible and undetectable, but they carry out some of the functions we think of as liver function. The only reason that these functions correlate with the liver is because that is where the liver fairies live. They become unhappy when their home is not healthy, and stop doing some of their functions.

Steven Novella, “Liver Fairies” at Neurologica Blog

Novella knows, of course, that no scientists believe in liver fairies but he believes that scientists who believe in dualism are merely the neurological equivalent of scientists who believe in liver fairies. Dualists believe (according to Dr. Novella) in “brain fairies”:

You have probably anticipated by this point where I am going will all of this. No one, as far as I know, has proposed the existence of liver fairies. This is because liver function is not integral to anyone’s belief system (again, as far as I know). But many people have proposed the exact same arguments for brain fairies, otherwise known as dualism. You can transpose all of the arguments I laid out above, for and against, by just changing liver to brain and liver function to mental function or mind. The arguments are the same, and they are just as vacuous.

Steven Novella, “Liver Fairies” at Neurologica Blog

Dr. Novella even anticipates a few of the pro-brain fairy arguments:

I anticipate some will argue that the analogy is not apt because liver function is physical, while mental function is not. But this is irrelevant, and also not true. Saying mental function is not physical is assuming your conclusion—the question is whether or not mental function is entirely physical. By all evidence it is—at least it is the abstract conception of what the brain does. It is not a thing, it is an activity. It is like saying that soccer is not physical. Sure, the soccer ball, field, nets, and players are physical, but the abstract concept of the game of soccer is not. Soccer is the activity, it is an idea, but the substrate is physical.

Steven Novella, “Liver Fairies” at Neurologica Blog

Dr. Novella presents his own theory of the mind-brain relationship. Let’s call it the “soccer fairy” thesis:

The same is true for mental function—it is what the biological brain does. The problem that some people have with this idea, however, is results from the fact that the brain evolved to create the seamless illusion of mental function. We are not aware of all the mechanistic aspects of brain function because it conspires to hid those mechanisms from our awareness. But we do see them none-the-less—every time we experience an optical illusion, hallucination, false memory, misperception, or other hiccup of the brain. We tend to brush or laugh off these experiences, but collectively they are another window into the mechanistic aspect of our mind…There are no brain fairies. It is an unnecessary hypothesis that is not even wrong. The mind is what the brain does.

Steven Novella, “Liver Fairies” at Neurologica Blog

There’s a lot here to discuss. A good place to begin is with Dr. Novella’s seemingly quite sensible assertion that “the mind is what the brain does.” This seems to be a version of a theory called functionalism. Dr. Novella is a bit imprecise about his own metaphysics but functionalism is the philosophical view that what makes a thing mental (rather than physical) depends only on its function, rather than on its matter. A thought is a thought because it does what thoughts do, regardless of the material substrate that gave rise to it.

This account, of course, gets the materialist off the hook. Materialists like Novella can explain (away) the causal gap between brains and thoughts by saying “Thoughts are what brains do” and leave it at that. It’s a “materialism of the gaps” argument.

There are problems with functionalism as an explanation of the mind. The most obvious problem is that functionalism, as understood in this way, is dualist. That is, Novella is invoking “what the brain is” and “what the brain does.” Even if his claims for functionalism are true, those are two different things.

An analogy would be the claim that “secreting bile is what the liver does.” That is true, to some extent, but it is a dualist understanding of the liver, in the sense that what the liver does is not the same as what the liver is. These are technically two different ontologies, The liver weighs three pounds and is shaped like a football. “Secreting bile” doesn’t have a weight or a shape because it’s an activity, not a physical thing. A patient with end-stage cirrhosis doesn’t have a failed “secreting-bile,” he has a failed liver. He needs a liver transplant, not a “secreting-bile” transplant.

Now I’m not being pedantic or parsing words when I say this: “The mind is what the brain does” isn’t a materialist theory because “the mind,” as Dr. Novella seems to define it (he’s vague), isn’t material. This gets us into some subtleties, which are inescapable here (and which Dr. Novella seems to avoid like a cat avoiding a bath).

There are several genuinely materialist theories of mind. They are:

  1. Behaviorism: The theory that the only testable and relevant aspect of a mind state is its behavioral correlate. Some behaviorists are agnostic about the actual existence of mind states; some deny them and some admit them but don’t care about them. Behaviorism is at least consistent with materialism (although a wag could argue that even behavior isn’t material). However, behaviorism is dead as a scientific enterprise*, so it need not concern us except as an example of a shining scientific error.
  2. Identity theory: This is the materialist theory that dominated the mid-20th century. On this view, mental states are identical to brain states. That is, your perception of pain when you prick your finger is identical to the action potentials and neurotransmitters active when you feel the pain. Identity theorists don’t merely argue for a correlation between mind and brain states. They argue that mind and brain are the same thing, understood from different perspectives.

There are a couple of flavors of identity theory—type and token. Type identity theory posits that mental states are identical to types of organization of the nervous system but not necessarily to the physical components themselves. Perhaps this is what Novella means by “the mind is what brain does,” although he doesn’t quite say so. Token identity theory posits that mental states are identical to actual physical constituents—your pain is actually your nerves, neurotransmitters, etc.

The problem with identity theory is that it violates Leibnitz’s Law, which is basic to logic. Colloquially, Leibnitz’s Law states that if things are identical, then they must be exactly the same in all respects. To claim that two different things are identical is nonsense. Two balls of unequal size can be similar or analogous but they are not identical because one is one size and the other is another size.

Identity theory violates Leibnitz’ Law even in its basic formulation. To state that your pain is identical to your neurotransmitters is a fallacy because your pain and your nerves can be (trivially) distinguished from one another, at least in the sense that you speak of “pain” and “nerves” as different things. I can see your nerves, but I can’t see your pain. Your nerves (in your arm) are two feet long, but your pain isn’t two feet long. Pain isn’t the same thing as nerves or action potentials so they aren’t identical. Thus identity theory is wrong. Identity theory is in eclipse today because it’s gibberish.

  1. Eliminative materialism: Even (some) materialists understand the problems with behaviorism and identity theory so the latest and most popular iteration of materialism is eliminative materialism. Eliminative materialists acknowledge that the mind can’t be explained in terms of matter, so they eliminate the mind. Please understand: they don’t claim that the mind is irrelevant (behaviorism) or that it is material (identity theory). They claim that there are no minds. They assert that we have no mind and no thoughts. It’s all matter, all the way down, and we merely make a category error by using the word “mind.” They call that folk psychology (as in “folk tale”). We are just foolish meat robots who believe we have minds.

In the eliminative materialist view, there are no mental states at all, just physical states. Your pain isn’t your nerves. You don’t have pain. You just have nerves. Yet one presumes that eliminative materialists still request Novocaine at the dentist’s office. That’s not, mind you, because they don’t want pain (which does not exist) but because they don’t want (for some reason) the physical state of their nerves that we plain folk erroneously call “pain.”

By now, you may see the problem here: How do we believe that there are no beliefs? If eliminative materialism is true, then their own belief in eliminative materialism isn’t a belief. It’s a physical state, a certain concentration of neurochemicals that we (the uninitiated) foolishly call a belief. So a disagreement between an eliminative materialist and a dualist isn’t really a disagreement at all. It’s just two different concentrations of brain dopamine or whatever. Exactly how these chemicals in different skulls get into a “disagreement” is left vague.

At this point, you may get a bit uncomfortable, as you would if the guy you’re sitting next to on the subway starts talking about the fact that CNN is broadcasting directly into his brain. Eliminative materialism, aside from being logical nonsense, has a real flavor of crazy—except that an eliminative materialist would say that there is no “crazy”; there’s just chemicals we foolishly call crazy.

The most sensible reply to an eliminative materialist is to change your seat.

So I ask: Dr. Novella, where are you on this spectrum? It’s not even clear that you’re a materialist, because “the mind is what the brain does” is a dualist assertion. If you are a materialist, are you a behaviorist, an identity theorist, an eliminative materialist, or a species of materialist yet to be named? What do you actually believe, other than your dualist assertion that “the mind is what the brain does”?

Belief in “brain fairies” looks pretty good compared to materialism. At least brain fairies aren’t logical nonsense. But I don’t believe in brain fairies. I am a Thomistic dualist. I believe that the soul is the Aristotelian form of the body, and that certain aspects of the soul—the human capacity for abstract thought and free will—are immaterial powers of the human soul.

I am happy to debate this with Dr. Novella in detail (including a rigorous look at the neuroscientific evidence), but first I’d like to know what kind of materialism Dr. Novella actually believes.

* A quite plausible case can be made that behaviorism was the only scientific theory that was destroyed by a joke. It goes ‘After a night of passion, one behaviorist turns to the other and says “That was good for you. How was it for me?”

Note: The photo of Steven Novella above was taken by Zooterkin (CC BY-SA 3.0) at TAM2013, where Dr. Novella was introducing the panel Medical Cranks and Quacks.

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Michael Egnor

Senior Fellow, Center for Natural & Artificial Intelligence
Michael R. Egnor, MD, is a Professor of Neurosurgery and Pediatrics at State University of New York, Stony Brook, has served as the Director of Pediatric Neurosurgery, and award-winning brain surgeon. He was named one of New York’s best doctors by the New York Magazine in 2005. He received his medical education at Columbia University College of Physicians and Surgeons and completed his residency at Jackson Memorial Hospital. His research on hydrocephalus has been published in journals including Journal of Neurosurgery, Pediatrics, and Cerebrospinal Fluid Research. He is on the Scientific Advisory Board of the Hydrocephalus Association in the United States and has lectured extensively throughout the United States and Europe.

Why the Mind Can’t Just Be the Brain