The following is an essay I wrote four years ago, did nothing with, and might as well publish here.
The Mind is More Than the Brain: A consideration of Ch. 49, Book II of the Summa Contra Gentiles
All references from the Summa Contra Gentiles are from the edition published by the University of Notre Dame Press, 1975
Is modern neuroscience on the verge of a definitive proof that there is no such thing as the immaterial mind? That what we call "ourselves" is really just an illusion of brain chemistry? According to John Derbyshire of the National Review (Dec. 13, 2004), novelist Tom Wolfe thinks so. From Derbyshire's review of I Am Charlotte Simmons:
Our understanding of brain function has gone much further than most non-scientists realize. Nowhere in that understanding is there any trace of a notion of the conscious self. According to Wolfe, practically no working neuroscientist believes that such a thing exists. The "I" that is the first word of Wolfe's title may, science tells us, be an illusion; and the fate of his heroine suggests that this is indeed so.
Derbyshire himself is skeptical of the immaterial "I" and is worried about the social consequences:
The vulgar metaphysic we all carry round with us includes the vague idea of a self, an "I," imagined as a little homunculus crouched inside our heads an inch or so behind the eyes, observing and directing all that goes on in our lives. It seems probable that this is as false as the medieval notion of the sky's being a crystal sphere. Yet if the self is indeed an illusion, then what is to prevent that dissolution of all values foreseen by Nietzsche? In Charlotte Simmons's world, a world without the self, what is virtue? What is wisdom? What is responsibility?
When I read such things, I am reminded of G.K. Chesterton's criticism of modern philosophy as the sort of thing that, if indulged in persistently, leads inevitably to the insane asylum. Socrates said that flute playing implies the existence of a flute player, and I am sure he would agree that understanding implies the existence of an understander. But the modern thinker exists in a bizarre world where there can be an "understanding" but no "notion of the conscious self", in other words, no understander, which is just what the conscious self is. This is a world where we must bow reverently when "science tells us" things because the abstraction "science" is more real than the self-consciousness of the scientists who do it. Chesterton wrote that the modern mentality is less an argument that can be rationally refuted than a spell that must be snapped. Indeed, how do you argue with a man who claims that he heard on the radio that he has no ears? Or with a scientist who says he understands that he has nothing with which to understand?
There is irony in the fact that the acknowledged founder of modern thought, Rene Descartes, based his thinking on the one thing he thought impossible to doubt, the "I", the very thing now questioned by modern scientists. But have scientists answered Descartes? Descartes thought the "I" was impossible to doubt because only something that exists can be deceived. If the "I" doesn't exist, then it can't be deceived. If it does exist, then it can be deceived about many things, but not about its own existence. I might have a dream, but my dream doesn't have dreams. Only really existing things can have real thoughts about anything, whether true or false. The modern scientist says that the "I" is an illusion, but never explains how an illusion can have real thoughts, let alone come to know itself as an illusion.
A further irony is that modern thinkers like Derbyshire view the self as a medieval notion to be cast off with other outdated ideas, like the heavens as a crystal sphere. But, as already noted, the notion of the "self" the moderns wish to debunk really started with their patriarch Descartes, not Aristotle or Aquinas. Furthermore, the notion of ourselves as merely a dream of the brain is nothing but a spin on the even more ancient idea that the world is nothing but the dream of God. And the answer given by medieval philosophers is the same in either case. If we are merely the dream of God, then God might know it, but we wouldn't, or anything else for that matter. A dream is not an agent, that is, something that can do something of itself. And if the self is an illusion of the brain, then the brain might know it, but the "I" wouldn't or anything else. The "I" would be known but not know. Common sense is on the side of the medievals: Dreams and fantasies are things experienced, not things that have experiences.
But the modern scientist thinks he can trump all this common sense with "science." By plugging in supercomputers, turning on high-powered microscopes, and firing up the Bunsen burner, he thinks he can get behind the self with technology. Aquinas might politely tell him that he can no more do this than get behind his own shadow. The shadow and the "I" keep tagging along, no matter how the modern scientist twists and turns. Take, for instance, Derbyshire's suggestion that the "self" is a "vague idea", part of a vulgar metaphysic that "we" carry round. One might ask: What do you mean by "we", pale face? If the "I" is suspect, who is this "we" that carries him around and suffers so patiently his commands in directing "our lives?" Is he suspect as well? Of course, the "we" is really nothing but the "I" in disguise reflecting on itself, as can easily be seen by putting the sentence into the personal singular instead of the plural:
The vulgar metaphysic I carry round with me includes the vague idea of a self, an "I," imagined as a little homunculus crouched inside my head an inch or so behind my eyes, observing and directing all that goes on in my life.
It immediately becomes clear that the true "I" is actually the I that is the voice of the sentence, not the homunculus "I" of the vulgar metaphysic. The only thing proven by his statement is that Derbyshire has mistaken the "I" of his vulgar metaphysic for the self of serious philosophical reflection. The fact is that any statement made by anyone about anything is made by an "I", and there is no gainsaying the voice of assertion. The "I" is the ground of experience, any experience, be it climbing the Alps, dreaming of soccer glory, philosophizing, conducting scientific investigations, or claiming that the "I" itself is an illusion. Derbyshire's homunculus "I" may be an illusion, but the "I" that proclaims it so certainly can't be.
The problem for moderns is that they forget that there is no such thing as "science", except as an abstraction. There exist scientists, "I"s like you and me, who do fruitful and laudable work in empirical investigation. But the scientific method has not granted them a supernatural (indeed superdivine) power to step outside their own consciousness and judge it an illusion. From what ground does the neuroscientist announce that the self is an illusion? Anything he says, does,or thinks occurs only in the context of his self-consciousness and is a product of that self-consciousness. Thus, when the neuroscientist announces that the self is an illusion, the first thing we should wonder about is not what happens to virtue, wisdom, and responsibility, but what happens to science. If there isn't a self around to be virtuous, wise, or responsible, then there isn't a self around to make scientific judgments. Or does Charlotte Simmons's self suddenly become solid the day she gets a Phd in biology?
Why are scientists so keen to dismiss the self? Lately they have been able to map mental activity onto brain activity with increasing accuracy. A subject plays the piano and one area of the brain becomes active. He watches TV and a different area becomes active. A certain area of his brain is stimulated and he feels a particular emotion. A different area is stimulated and he feels a different emotion. Moreover, various mental activities become impossible in the case of brain injuries. One lesion makes a patient unable to read, another makes him mistake his wife for a hat. The mind is so intimately involved with the brain that the scientist suspects that the mind is nothing but the brain. There is no independent "I" in there. The flickering neurons are all there is.
To which Aquinas might say: So what? That the mind and the body are intimately involved is obvious to common sense and is a fundamental principle of Thomistic philosophy. I will my right arm to rise and the appendage on that side goes up. It does not follow that "willing my arm to rise" is nothing but the physical phenomenon of "right arm rising." I think "2+2=4" and a certain area of my brain becomes electrically active. It does not follow that "2+2=4" is nothing but the physical phenomenon of "certain part of the brain becoming electrically active." The electrical activity in the brain is the effect of thinking "2+2=4", not the thought itself, as my arm rising is the effect of willing that phenomenon, not the willing itself. Nor does it prove anything that brain lesions inhibit mental activity. It was a commonplace of medieval philosophy that a sick man can't think straight.
At this point the modern thinker says: Aha! Just like a medieval, inventing fantastical beings where none are needed. Why invent this "I" that has "effects" in the brain? We can already explain much of mental activity as electrical activity in the brain. Eventually we will explain all of it, having finally finished chasing the self through ever narrower and darker passageways of the brain, in the words of Mr. Derbyshire.
But has the modern scientist explained thoughts like "2+2=4" in terms of brain activity? Mapping thoughts to brain activity is one thing, explaining it as brain activity is quite another, and we finally come to the subject of this essay, Ch. 49 of Book II of the Summa Contra Gentiles, "That the intellectual substance is not a body." In this Chapter St. Thomas gives several arguments why what he calls the "intellectual substance" (and we would call the "mind") cannot possibly be a physical body. His arguments, as always for St. Thomas, are concise and to the point. And also typically for St. Thomas, a quick read of the chapter shows that the thrust of the argument does not depend on crystal spheres or any particular results from medieval physics. Whether true or false, the argument stands on its own and is not dependent on the vagaries of empirical science, ancient or modern. Consider the argument in paragraph 6:
Moreover, if the intellectual substance is a body, it is either finite or infinite. Now, it is impossible for a body to be actually infinite, as is proved in [Aristotle's] Physics. Therefore, if we suppose that such a substance is a body at all, it is a finite one. But this is also impossible, since, as was shown in Book I of this work, infinite power can exist in no finite body. And yet the cognitive power of the intellect is in a certain way infinite; for by adding number to number its knowledge of the species of numbers is infinitely extended; and the same applies to its knowledge of figures and proportions. Moreover, the intellect grasps the universal, which is virtually infinite in its scope, because it contains individuals which are potentially infinite. Therefore, the intellect is not a body.
One reason people are so quick to conflate the mind and brain is because of the analogy with digital computers. The billions of neural connections in the brain seem like the billions of electronic connections in a computer. And the electrical activity the neuroscientist observes in the brain seems to bear a resemblance to the electronic activity of a computer. Since computers obviously don't have an immaterial "I", maybe the brain doesn't either. The computer/brain analogy is seductive, but St. Thomas has put his finger on a fatal problem with it. A computer represents a number by using a particular electrical pattern involving high voltage (denoted by "1") and low voltage (denoted by "0"). The number "5", for example, would be represented by the electrical pattern 1-0-1 and the number "6" by 1-1-0. Larger numbers need larger patterns: The number "8" is 1-0-0-0, "63" is 1-1-1-1-1-1 and "25000" is 1-1-0-0-0-0-1-1-0-1-0-1-0-0-0. But a computer has limited electrical resources and therefore a limited number of patterns. No matter how big a computer is or how fast its circuits, there will always be numbers that are too large for it to represent. Similarly, our brains, simply by the fact of being physical, necessarily have a limited number of neural connections and so a limited number of patterns with which they could represent numbers. As St. Thomas points out, our minds are not limited in the size of the numbers they can think about. Give me any number, and I can always think of a larger one. (Don't confuse imagining a number with thinking about one. Imagining a number means forming a picture of that many things, like forming a picture of a dozen eggs in your head. Our capacity to do that is very limited, but we can think about things even if we can't imagine them. I can't imagine a million coins, but I can think about the number 1,000,000. I do so everytime I use 1,000,000 in an arithmetic calculation.) There is no limit to the size of the numbers our minds can think about. It follows that the mind that thinks about number cannot be physical.
St. Thomas also makes reference to our knowledge of "figures and proportions". I can think about triangles, squares, pentagons, etc. (Again, there is a difference between thinking about a figure and imagining one.) In fact, the number of different figures I can think about is unlimited. But if the thought "triangle" is nothing but a particular electrical pattern in the brain, then the number of figures I can think about would be limited, since the number of electrical patterns in the brain is limited, however large. This is a variation on the argument in the last paragraph and the conclusion is the same: The mind can't be physical because of the unlimited nature of its thoughts.
Consider the argument in paragraph 8:
Also, the action of no body is self-reflexive. For it is proved in [Aristotle's] Physics that no body is moved by itself except with respect to a part, so that one part of it is the mover and the other is the moved. But in acting, the intellect reflects on itself, not only as to a part, but as to the whole of itself. Therefore, it is not a body.
This argument always makes me think of computers in film. Back in the 50's and 60's, computers were cast as "Giant Brains", brilliant machines tended by acolytes in white lab coats and capable of thinking brilliant thoughts. Later, in 2001: A Space Odyssey, the villainous computer HAL not only is intelligent but assumes a will of its own, taking over the space mission and killing the astronauts. This theme continued in 1983 in Wargames, where a computer attempts to start a nuclear war on its own initiative. The latest installment in this genre is the Matrix series, where computers not only take over but force human beings to live in an artificial reality. What's fascinating about these movies is how silly they look in retrospect. The "giant computers" from the 50's, for example, had less computing power than a modern handheld calculator that you can buy for $10 at Walmart. And the infamous WOPR computer from Wargames is left in the dust by a Dell desktop PC that you can buy for a couple of hundred bucks. Nobody these days would believe a movie where a handheld calculator manifests brilliant insight or your $300 desktop takes over your life. Our intimacy and familiarity with computers has demystified them. How many times have we wished our computer would show some intelligence when a day's work is lost because of a trivial operating system error? Everyday use has brought home the truth about physical bodies of which Aristotle and St. Thomas speak: It is the nature of physical beings that one part of it is the mover and the other is the moved. I move the keys on the keyboard and a program is moved to access the harddrive. The movement on the harddrive in turn moves the program to display data on the monitor. Any break in the chain and the computer doesn't work - and the longer the chain, the more opportunities for it to break, which is why computers become more frustrating with complexity, not less. We see that the intelligence attributed by people in the 60's to computers is a superstition. Computers don't have the unity necessary to intelligence. The keyboard knows nothing about the harddrive, the harddrive knows nothing about the CPU, and the CPU knows nothing about the monitor. They are just electrical components obeying the laws of physics, moving when they are moved by another. The unity of the computer is all from our perspective. We connect harddrives, monitors, keyboards and CPUs, call it a "computer" and think of it as "one thing" doing something, but this is really a reflection of the unity of our own intelligence and not a unity in physical nature. Now if the mind is nothing but the brain, from where comes the unity of our thought? The brain, like a computer, is a collection of parts. But the mind is self-reflexive, that is, the mind acts on itself. It has the peculiar characteristic that it not only knows the thing known, but itself in the act of knowing it, and that with the whole of itself. When I know 2+2=4, I not only know the mathematical truth, but the fact that I know it, and it is the same mind that knows both things. This makes the mind both the mover and the thing moved. How can this be if the mind is a physical body? It is all well and good that neuroscientists can detect electrical signals in the brain when a subject thinks 2+2=4 or 4+4=8. But if they claim that these electrical signals are thought itself, they need to explain the unity of the mind in terms of electrical signals, an impossibility to my thinking.
The argument of paragraph 9 also depends on the self-reflexive character of the mind:
A body's action, moreover, is not terminated in action, nor movement in movement - a point proved in [Aristotle's] Physics. But the action of an intelligent substance is terminated in action; for just as the intellect knows a thing, so does it know that it knows; and so on indefinitely. An intelligent substance, therefore, is not a body.
The self-reflexive character of the mind is one of those facts that is so obvious it is often overlooked. It is expressed in John Derbyshire's rumination about the "I" that "we" carry around. The "we" that is the voice of the sentence is the same "I" that is under discussion. We could write a further sentence where "we" discuss the voice of John Derbyshire's sentence, in other words, where "we" discuss the "we" that is thinking about the "I". This process could be carried on indefinitely and is implicit in any act of knowledge. What it means is that the result of the minds act of knowing is another act of knowing, ad infinitum. But no body can act in this way. Suppose, to the contrary, that thoughts really are nothing but electrical signals in the brain. Then since knowing something implies that we know that we know it, the electrical signal of knowing it will give rise to another electrical signal that is the physical manifestation of knowing that we know it. This signal will give rise to yet another one, and on indefinitely, and the brain would soon fry itself. Therefore the mind cannot be not identical with the brain.
The preceeding arguments are probably the ones most accessible to the modern mind. But it is the argument from paragraph 4 that I find most persuasive:
Again, the principle of diversity among individuals of the same species is the division of matter according to quantity; the form of this fire does not differ from the form of that fire, except by the fact of its presence in different parts into which the matter is divided; nor is this brought about in any other way than by division of quantity - without which substance is indivisible. Now, that which is received into a body is received into it according to the division of quantity. Therefore, it is only as individuated that a form is received into a body. If, then, the intellect were a body, the intelligible forms of things would not be received into it except as individuated. But the intellect understands things by those forms of theirs which it has in its possession. So, if it were a body, it would not be cognizant of universals but only of particulars. But this is patently false. Therefore, no intellect is a body.
Let us suppose that the mind is nothing but the brain. Then my thoughts are nothing but patterns of neurons firing in the brain. My idea of "fire", for example, would then be some particular electrochemical pattern in my brain. Your idea of fire would be an electrochemical pattern in your brain. Common sense tells us that we can have a conversation about "fire" and talk about the same thing. Yet how can this be so? No two physical objects are identical in every respect. Even if the pattern for "fire" in your brain is similar to the pattern for "fire" in my brain, it won't be precisely identical in every respect. The space between the neurons will be slightly different and the timing of the neural firing will be slightly different in each brain. If the idea of fire is nothing but the physical pattern in each of our brains, then our ideas of "fire" will necessarily differ as well.
Well, maybe our ideas of fire are slightly different, you argue. Isn't that why people get in arguments? If that were the case, then arguments could never be resolved because we could never get our ideas of fire to be exactly the same. But we do, at least occasionally, resolve arguments in terms of mutually understood ideas. The point can be better made with a mathematical idea, say the number "2". What would happen if scientists hooked up their equipment and monitored each of our brains while we both thought of the number "2"? Would they get exactly the same readings on both our meters, down to the thousandth decimal of brain current? Would a picture of our brain activity show exactly the same thing, down to whatever resolution the scientists cared to go? Obviously not, and surely our ideas of "2" are not just approximately the same, but identical, otherwise mathematics is impossible. The fact that physical activity from one brain to the next is never exactly identical but we can nonetheless think of identical things shows again that brain activity is an effect of thought, not thought itself.
The problem with the material mind is even deeper than this, however. Even if it could be shown that brain activity might be precisely identical from one brain to the next, this would still do nothing to account for how two different brains could think of the same thing. As St. Thomas notes, material things are divided according to quantity. This apple differs from that apple because this apple has this matter and that apple has that matter. What makes this apple this apple is the particular matter of which it is constituted. In other words, matter is by its nature a source of individuation. So if we say that our minds, and therefore the ideas resident in them, are purely material beings, then they are also purely individual beings. Your idea of “2” is not the same as my idea of “2” because the matter in your head is not the same matter that is in my head. The fact that we can hold a conversation and talk about the same number “2” shows that “2”, and the mind that knows it, cannot be material.
An opponent might respond to the above arguments with something like this: Yes, the patterns in your head are not identical to the patterns in my head, and the matter in your head is not the same matter in my head. But that’s beside the point. The fact is that the pattern for “2+2=4” in your head is functionally equivalent to the pattern for “2+2=4” in my head, and that is all that is necessary. The voltage levels and electronic chips in computers vary slightly from machine to machine, yet they are functionally equivalent because they run the same software. If we think of software as the analog of the mind, then we can talk about “2” even if our minds are nothing but matter because we have functionally equivalent representations of “2”.
The flaw in this argument can be found by analyzing more closely the notion of function. When two things fulfill the same function they answer to the same purpose. A bow and arrow and a rifle can both serve the function of killing deer. The numbers “2” and “4” can both serve the function of producing an even number when multiplied by any other integer. An airplane and a ship can both function to get you across the Atlantic. Notice that the same things can be equivalent for some functions but not equivalent for other functions. A ship and an airplane are not functionally equivalent if the function is to go deep-sea fishing. The point is that the notion of “functional equivalence” implies a process or activity whose meaning is already known and taken for granted, and that provides the context for the functional equivalence. Thus to say that the material patterns for “2+2=4” in your head and my head may be different but functionally equivalent is to take for granted that the biochemical processes in the brain are in themselves mathematically meaningful, which is the very point at issue. Here is another way to look at it: What the notion of function does is displace meaning to the function level. Meaning is shifted from the element that serves the function to whatever it is that assigns meaning to the function itself. If a certain pattern in the brain serves the function of “2+2=4”, then it is serving the purpose of some other part of the brain when it wishes to use the notion of “2+2=4”. How are those parts of the brains related in our two brains? Are they also functionally equivalent? Then their meaning, too, is displaced and they must get it from yet another part of the brain, etc., etc. At each step we don’t solve the problem of how two materially distinct beings (the patterns in your head and my head) can yet be identical, but only apparently solve it by displacing it with the notion of function. But the buck will have to stop somewhere, and unless there is some point at which the processes in two different brains are not merely functionally identical but identical pure and simple, then the previous arguments stand. What about computers? Computers are purely functional, material beings with no intrinsic meaning. Computers are functionally equivalent because we human beings assign functional meaning to them with our non-material minds. “2+2=4” is functionally equivalent but electrically different in each computer because we find it so.