Saturday, May 19, 2012

Mind/Brain and the Evidence

Dr. Steven Novella, in this post on his blog, distinguishes between the questions of whether the brain causes the mind and exactly how the brain causes the mind. Citing David Chalmers, he states that it is not necessary to answer the latter question to establish the former. There can be evidence of causal linkage that does not require an exhaustive knowledge of the nature of that causal linkage. Novella summarizes the evidence that he thinks conclusively establishes the causal dependence of mind on brain in the form of the following predictions:
If the brain causes mind, then:
1- Brain states will correlate to mental and behavioral states.
2- Brain maturity will correlate with mental and emotional maturity.
3- Changing the brain’s function (with drugs, electrical or magnetic stimulation, or other methods) will change mental function.
4- Damaging the brain will damage the mind – producing specific deficits that correlate to the area of the brain damaged.
5- There will be no documentable mental phenomena in the absence of brain function.
6- When the brain dies, mental function ends.
Novella thinks that all six predictions have been well-established empirically.

We should remember that the traditional philosophical case for the immaterial mind does not deny that much of mental phenomena has a physical origin. In fact, the philosophers in the Aristotelian tradition insist that only one specific mental faculty - the intellect - requires an immaterial foundation. So if we are concerned with evaluating the classical philosophical case for the immaterial mind in terms of contemporary neuroscientific evidence, the only interesting evidence is that which relates to the intellect. Evidence that emotions or the sense of self have a physical origin may be interesting but it is irrelevant to the classical philosophical position, since the classical philosopher (and here I am taking Aquinas as the exemplar) did not deny such a thing. The interesting evidence relates to the question of whether the intellect is purely a material function of the brain.

Why did the classical philosophers make an exception for the intellect? Because the intellect is that which understands universals, and it is hard to see how a universal effect can have a material cause. Consider the emotion of anger. If I am angry, the emotion is restricted to me; even if you are simultaneously angry, your experience of the emotion is your's alone and my experience is mine alone. Each is a singular. There is no conceptual problem with thinking the emotion has a purely physical origin, since we encounter singular effects from material causes every day. I turn on my stove and it heats this pot of water, but not every pot of water in the universe. I throw a baseball and it breaks a window, but not every window in the universe, let alone every possible window in the universe. But instead of being angry, suppose we instead think about the emotion anger. (And I will italicize anger when referring to the idea of anger rather than the experience of being angry.) Now any number of emotions, and perhaps no emotion at all, may accompany our thinking about anger. We may be sad, happy, indifferent or, yes, angry when thinking about anger. Thinking about anger is something radically different than having the emotion anger.

But more importantly, when I think about the idea of anger, the idea doesn't merely apply to my own emotion, but your's and everybody else's as well. I may only be able to experience my own anger, but I can think about everybody's anger, and I can think about them all at the same time. Furthermore, you and I can engage in a conversation about anger and discuss exactly the same thing; I can only experience your emotion of anger as analogous to a similar emotion of my own, but we can both think about one and the same idea of anger.

This is close to what contemporary philosophers of mind call the problem of "intentionality", but it is not quite it. The problem of intentionality refers to how an idea can be about something, e.g. how my conscious thinking about the moon can be about the large rock orbiting the Earth and not just about itself. What I am talking about is the classical problem of universals, which is not so much about how thoughts can be about things, but about how different thoughts can be about the same thing as well as how a single thought can be about an infinite number of things (as my thinking about anger can be about everyone's personal experience of anger.)

Let's consider Novella's first line of evidence in terms of the intellect rather than conscious states that have a non-controversial physical origin (like emotions): "Brain states will correlate to mental and behavioral states." It is easy to see how this is possible with emotions like anger. I am not familiar with the specifics of the evidence, but it is not hard to imagine some particular regions of the brain becoming active in a specific way when one is angry, and a different region when one is happy (or, perhaps, the same region in a different way.) Now consider what might happen when you think about anger rather than become angry. Is there some specific pattern of neural firing that accompanies the state of thinking about anger? Is this pattern identical across subjects? Such identity doesn't matter so much in the case of emotion, since we need not require that your emotion of anger be identical to my own. But if we are to think in the abstract about anger, and have a conversation about it, then we do require that our ideas of anger be exactly the same, not only in terms of being just like each other, but in terms of being exactly the same idea. Suppose that measurements show that, physiologically, your thinking of anger is not exactly the same as my thinking of anger. Does this shows that your idea of anger is not exactly the same as my idea of anger, in which case our conversation (and perhaps all conversations) involve a fundamental misunderstanding because we aren't really talking about the same ideas when we think we are? Or is there some way in which we are still talking about exactly the same idea of anger even though the physiology between us is not precisely identical? The former alternative involves a whole train of unpleasant philosophical consequences, and the real challenge is to establish, even in principle, how the latter alternative might be true. If the physics is all there is, and the physics is not identical, it is difficult to see how we can say the ideas are identical. Or, put in empirical terms, if an idea is a "brain state", then variations in brain states just are variations in ideas; saying two ideas aren't the same is the same as saying two brain states aren't the same and vice versa. But I am convinced that we can talk about identically the same ideas, whatever the similarity of our brain states, which is one reason Novella's summary of evidence does not yet convince me.

Suppose, however, that physiologically your thinking of anger is identical to my own to some degree of precision. In other words, the neuroscientists are successful in identifying a brain state correlated to anger that is identical among all human subjects. Another problem surfaces, and it is easier to see in the case of mathematical ideas. I am thinking of the number "one", which presumably correlates to a brain state. Now I think of the number "two", which presumably correlates to a different brain state. The brain is a finite physical organ; it is capable of assuming a vast but not infinite number of states. How many states can the brain assume in theory? A trillion? A quadrillion? A trillion trillion trillion? Whatever the number is, and let us call it a trillion for the sake of argument, what does it mean if I think of the number a trillion plus one? If thinking of a number corresponds to a brain state, then the potential numbers I might think about are finite, since the brain is finite. But this is clearly false; since I might potentially think about any number - and in particular, the number one more than whatever you say is the number of brain states. It must be true, then, that multiple numbers correspond to identical brain states in my thinking. How does, the materialist, then, account for a diversity of numbers derived from identical brain states? It is hard to see how the materialist case could possibly be sustained, since the distinction of numbers in this case would seem to require something immaterial - which is why the classical philosophers thought the intellect (that which conceives ideas) must be immaterial, even if the rest of mental life could be accounted for physically.

These sorts of questions are the real challenge (as far as I am concerned) for the materialist, and the classical philosophical case for the immaterial mind hasn't even been challenged until they are addressed. There are some conclusions to be drawn here about the interesting directions of scientific investigation. Instead of investigating brain state correlation to things like emotions or the sense of self - which even Aquinas held could have a purely physical basis - the investigation should correlate brain states to intellectual states. What is the brain state correlating to the thinking of the number "three?" Or thinking about the Pythagorean Theorem? Or thinking about the theory that the mind has a purely material basis? If we can stimulate brain states like emotions artificially, can we also stimulate intellectual states artificially? Can we stimulate someone to think of the number "three?" Or to think of the Pythagorean Theorem? I would find the results of such research extremely interesting. (I strongly suspect, of course, that there is no way to stimulate the brain to think of the number "three", precisely because multiple numbers (in fact, an infinity of numbers) must correspond to identical brain states. Merely physical stimulation would be "underdetermined" as far as what number would be thought.)


EdT said...


Interesting line of argument. Would Dr. Novella argue that there is a limit to how big a number you can think of,i.e. put into memory, therefore there is no problem mapping to brain state. For example does your mind really distinguish between 2 20 digit numbers that are only different in the 17th digit? I doubt if I told you to think of the first 20 digit # you could actually think about the # itself. You would rather think about "the # labelled the first #" or "the # with the 17th digit = 5".
This is one of many interesting posts of late.

David T. said...


I think we need to distinguish between the imagination and the intellect. The imagination is physically based and limited, so you can't actually imagine a very large number. But the very fact that we can use large numbers in math means that we can conceive of them in the intellect. Otherwise we would be entirely ignorant of their existence.

Compare the intellect with the senses. Our hearing and sight is limited. We can't see something in low light, and too much light blinds us. We can't hear high frequency sounds; they don't exist for us as far as hearing is concerned. If we also couldn't conceive of high frequency sound in the intellect, then we would be entirely ignorant of it and couldn't speak of it at all, because it would be entirely beyond us. Like an ant knows nothing about the stars, or the possibility of stars.

There is some number of brain states. Whatever that number is, we can conceive it, or we wouldn't be able to talk about it. We would go through life without it ever occurring to us that such a number might be. And we can conceive of every integer in between.

AYC said...


AYC said...

I don't think the mind needs to be infinite to conceive of infinity. The members of a finite set can be combined and recombined in an infinite number of ways. In mathematics we conceive of infinite numbers using a base of just ten numerals. I'm sympathetic to the notion that the mind is something beyond the brain, but I don't think this argument is a strong one.

David T. said...

Well, thinking of "3" is a distinct brain state, and thinking of "2" is a distinct brain state. What about thinking of "32"? Surely it must be a distinct brain state as well, even if it uses the digits "3" and "2". So we end up with an infinity of possible brain states from a base 10 number system.

AYC said...

I suppose what I was trying to say is that an infinite number of possible brain states is true, but doesn't require a mystical explanation; if we can extrapolate infinity from a finite base of numerals, why can't a finite brain be capable of infinite possible brain states in the same way?

This reminds me of Zeno's argument against motion based on the fact that distances are infinitely divisible.

AYC said...

Being infinitely divisible doesn't make a mile infinitely long....

David T. said...


I think we need to keep in mind the distinction between abstract geometrical objects (like lines) and physical objects like brains.

A line can potentially be divided in an infinite number of different places. The distances between two points on a line can also be taken as arbitrarily small as you like; in other words, you can always find another point closer to a test point than a point you've already chosen.

But with a physical object like a brain, at some point the differences between brain state 1 and brain state 2 have got to be so small as to be practically inconsequential (or undetectable). Just as, with a practical ruler than an abstract line, there comes a point where it is impossible to distinguish between two different physical points on the ruler, for whatever purposes you choose. In the same way, there aren't an infinity of brain states because at some point brain states become indistinguishable.