Eliminativism and the Neuroscience of Consciousness

I am teaching Introduction to Neuroscience this spring semester and am using An Introduction to Brain and Behavior 5th edition by Kolb et al as the textbook (this is the book the biology program decided to adopt). I have not previously used this book and so I am just getting to find my way around it but so far I am enjoying it. The book makes a point of trying to connect neuroscience, psychology, and philosophy, which is pretty unusual for these kinds of textbooks (or at least it used to be!).

In the first chapter they go through some of the basic issues in the metaphysics of the mind, starting with Aristotle and then comparing Descartes’ dualism to Darwin’s Materialism. This is a welcome sight in a neuroscience/biological psychology textbook, but there are some points at which I find myself disagreeing with the way they set things up. I was thinking of saying something in class but we have so little time as it is. I then thought maybe I would write something and post it on Blackboard but if I do that I may as well have it here in case anyone else wants to chime in.

They begin by discussing the greek myth of Cupid and Psyche and then say,

The ancient Greek philosopher Aristotle was alluding to this story when he suggested that all human intellectual functions are produced by a person’s psyche. The psyche, Aristotle argued, is responsible for life, and its departure from the body results in death.

Thus, according to them, the ordinary conception of the way things work, i.e. that the mind is the cause of our behavior, is turned by  Aristotle into a psychological theory about the source or cause of behavior. They call this position mentalism.

They also say that Aristotle’s view was that the mind was non-material and separate from the body, and this is technically true. I am by no means an expert on Aristotle’s philosophy in general but his view seems to have been that the mind was the form of the body in something like the way that the shape of a statue was the form of (say) some marble. This is what is generally referred to as ‘hylomorphism’ which means that ordinary objects are somehow composed of both matter and form. I’ll leave aside the technical philosophical details but I think the example of a statue does an ok job of getting at the basics.  The statue of Socrates and the marble that it is composed out of are two distinct objects for Aristotle but I am not sure that I would say that the statue was non-physical. It is physical but it is just not identical to the marble it is made out of (you can destroy the statue and not destroy the marble so they seem like different things). So while it is true that Aristotle claimed the mind and body were distinct  I don’t think it is fair to say that Aristotle thought that the psyche was non-physical. It was not identical to the body but was something like ‘the body doing what it does’ or ‘the organizing principle of the body’. But ok, that is a subtle point!

They go on to say that

Descartes’s thesis that the [non-physical] mind directed the body was a serious attempt to give the brain an understandable role in controlling behavior. This idea that behavior is controlled by two entities, a [non-physical] mind and a body, is dualism (from Latin, meaning two). To Descartes, the [non-physical] mind received information from the body through the brain. The [non-physical] mind also directed the body through the brain. The rational [non-physical] mind, then, depended on the brain both for information and to control behavior.

I think this is an interesting way to frame Descartes view. On the kind of account they are developing Aristotle could not allow any kind of physical causation by the non-physical mind but I am not sure this is correct.

But either way they have an interesting way of putting things. The question is what produces behavior? If we start with a non-physical mind as the cause of behavior then that seems to leave no role for the brain, so then we would have to posit that the brain and the non-physical mind work together to produce behavior.

They then go on to give the standard criticisms of Descartes’ dualism. They argue that it violates the conservation of energy, though this is not entirely clear (see David Papineau’s The Rise of Physicalism for some history on this issue). They also argue that dualism is a bad theory because it has led to morally questionable results. In particular:

Cruel treatment of animals, children, and the mentally ill has for centuries been justified by Descartes’s theory.

I think this is interesting and probably true. It is a lot easier to dehumanize something if you think the part that matters can be detached. However I am not sure this counts as a reason to reject dualism. Keep in mind I am not much of a dualist but if something is true then it is true. I tend to find that students more readily posit a non-physical mind for animals than they do deny that they have pain as Descartes did but that is neither here nor there.

Having set everything up in this way they then introduce eliminativism about the mind as follows.

The contemporary philosophical school eliminative materialism takes the position that if behavior can be described adequately without recourse to the mind, then the mental explanation should be eliminated.

Thus they seem to be claiming that the non-physical aspect of the system should be eliminated, which I think a lot of people might agree with, but also that along with it the mental items that Descartes and others thought were non-physical should be eliminated as well. I fully agree that, in principle, all of the behaviors of animals can be fully explained in terms of the brain and its activity but does this mean that we should eliminate the mind? I don’t think so! In fact I would generally think that this is the best argument against dualisms like Descartes’. We have never needed to actually posit any non-physical features in the explanation of animal behavior.

In general the book tends to neglect the distinction between reduction and elimination. One can hold that we should eliminate the idea that pains and beliefs are non-physical mental items and instead think that they are physical and can be found in the activity or biology of the brain. That is to say we can think that certain states of the brain just are the having of a belief or feeling of a pain, etc. Eliminativism, as it is usually understood, is not a claim about the physicality of the mind. It is instead a claim about how neuroscience will proceed in the future. That is to say the emphasis is not on the *materialism* but on the *eliminative* part. The goal is to distinguish it from other kinds of materialism not to distinguish it from dualism. The claim is that when neuroscience gives us the ultimate explanation of behavior we will see that there really is no such thing as a belief. This is very different from the claim that we will find out that certain brain states are beliefs.

Thus it is a bit strange that the authors run together the claim that the mind is a non-physical substance together with the claim that there are such things as beliefs, desires, pains, itches, and so on. This seems to be a confusion that was evident in early discussions of eliminativism (see the link above) but now we know we can eliminate one and reduce the other, though we may not as well.

They go on to say,

Daniel Dennett (1978) and other philosophers, who have considered such mental attributes as consciousness, pain, and attention, argue that an understanding of brain function can replace mental explanations of these attributes. Mentalism, by contrast, defines consciousness as an entity, attribute, or thing. Let us use the concept of consciousness to illustrate the argument for eliminative materialism.

I do not think this is quite the right way to think about Dennett’s views but it is hard to know if there is a right way to think about them! At any rate it is true that Dennett thinks that we will not find anything like beliefs in the completed neuroscience but it is wrong to think that Dennett thinks we should eliminate mentalistic talk. It is true, for Dennett, that there are no beliefs in the brain but it is still useful, on his view, to talk about beliefs and to explain behavior in terms of beliefs.

He has lately taken to comparing his views with the way that your desktop computer works. When you look at the desktop there are various icons there and folders, etc. Clicking on the folder will bring up a menu showing where your saved files are, etc. But it would be a mistake to think that this gave you any idea about how the computer was working. It is not storing little file folders away. Rather there is a bunch of machine code and those icons are a convenient way for you to interface with that code without having to know anything about it. So, too, Dennett argues our talk about the mind is like that. It is useful but wrong about the nature of the brain.

At any rate how does consciousness illustrate the argument for eliminative materialism?

The experimenters’ very practical measures of consciousness are formalized by the Glasgow Coma Scale (GCS), one indicator of the degree of unconsciousness and of recovery from unconsciousness. The GCS rates eye movement, body movement, and speech on a 15-point scale. A low score indicates coma and a high score indicates consciousness. Thus, the ability to follow commands, to eat, to speak, and even to watch TV provide quantifiable measures of consciousness contrasting sharply with the qualitative description that sees consciousness as a single entity. Eliminative materialists would argue, therefore, that the objective, measurably improved GCS score of behaviors in a brain-injured patient is more useful than a subjective mentalistic explanation that consciousness has “improved.”

I don’t think I see much of an argument for eliminativism in this approach. The basic idea seems to be that we should take ‘the patient is conscious’ as a description of a certain kind of behavior that is tied to brain activity and that this should be taken as evidence that we should not take ‘consciousness’ to refer to a non-physical mental entity. This is interesting and it illustrates a general view I think is in the background of their discussion. Mentalism, as they define it, is the claim that the non-physical mind is the cause of behavior. They propose eliminating that but keeping the mentalistic terms, like ‘consciousness’. But they argue that we should think of these terms not as naming some subjective mental state but as a description of objective behavior.

I do agree that our ordinary conception of ‘consciousness’ in the sense of being awake or asleep or in a coma will come to be refined by things like the Glasgow Coma Scale. I also agree that this may be some kind of evidence against the existence of a non-physical mind that is either fully conscious or not at one moment. As the authors themselves are at pains to point out we can take the behavior to be tied to brain activity and it is there that I would expect to find consciousness. So I would take this as evidence of reduction or maybe slight modification of our ordinary concept of waking consciousness. That is, on my view, we keep the mental items and identify them with brain activity thereby rejecting dualism (even though I think dualism could be true, I just don’t think we have a lot of reason to believe that it is in fact true).

They make this clear in their summary of their view;

Contemporary brain theory is materialistic. Although materialists, your authors included, continue to use subjective mentalistic words such as consciousnesspain, and attention to describe more complex behaviors, at the same time they recognize that these words do not describe mental entities.

It think it should be very clear by now that they mean this as a claim about the non-physical mind. The word ‘consciousness’ on their view describes a kind of behavior which can be tied to the brain but not a non-physical part of nature. But even so it will still be true that the brain’s activity will cause pain; as long as we interpret ‘pain’ as ‘pain behavior’.

However, I think it is also clear by now that we need not put things this way. It seems to me that the better way to think of things is that pain causes pain behavior, and that pain is typically and canonically a conscious experience, and that we can learn about the nature of pain by studying the brain (because certain states of the brain just are states of being in pain).  We can thereby be eliminativists about the non-physical mind while being reductionists about pain.

But, whichever way one goes on this, is it even correct to say that modern neuroscience is materialistic? This seems to assume too much. Contemporary neuroscience does make the claim that an animal’s behavior can be fully understood in terms of brain activity (and it seems to me that this claim is empirically well justified) but is this the same thing as being materialistic? It depends on what one thinks about consciousness. It is certainly possible to take all of what neurosciences says and still think that conscious experience is not physical. That is the point that some people want to make by imagining zombies (or claiming that they can). It seems to them that we could have everything that neuroscience tells us about it and its relation to behavior and yet still lack any of the conscious experience in the sense that there is something that it is like for the subject. I don’t think we can really do this but it certainly seems like we can to (me and) a lot of other people. I also agree that eliminativism is a possibility in some sense of that word but I don’t see that neuroscience commits you to it or that it is in any way an assumption of contemporary brain theory.

It wasn’t that long ago (back in the 1980s) that Jerry Fodor famously said, “if commonsense psychology were to collapse, that would be, beyond comparison, the greatest intellectual catastrophe in the history of our species” and I tend to agree (to a somewhat less hyperbolic way of putting the point). The authors of this textbook may advocate eliminating our subjective mental life but that is not something that contemporary neuroscience commits you to!

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One thought on “Eliminativism and the Neuroscience of Consciousness

  1. Let’s start with the most simple question any valid intellectual or professional approach would ask – how can we measure consciousness, or mind, or emotions, or any other pop cultural belief – across species? If we cannot, then how can we claim it is biologically, medically or physiologically valid and not patently non-sensical?

    I assume we can dismiss metaphysics as just another claim to magic, like religion and the rest of philosophy – and pretty much all economics and the humanities.

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