Motus Mentis

I’ve been spending a lot of time over at Bill Vallicella’s place lately, as anyone who reads these posts is bound to have noticed. We’ve been arguing dualism vs. phsyicalism, and the fur has been flying. Here’s a recap. I apologize if this post is of rather unseemly length.

First, a few words about my own point of view. My intuitions impel me toward physicalism. I was raised by two scientists, and the impressive gains that the scientific/physicalist program has achieved in the past, and its tendency to correct itself, albeit slowly, in response to undigestible empirical results makes me optimistic that even the most difficult questions about the workings of the world will one day yield. As W.V.O. Quine put it, physics is the science that aims at “full coverage”. If there are lawful regularities in the world, physics aims to understand them, even if that means doing so in terms of forces, and types of matter, that are as yet unknown.

Dualists believe there is more to the world than physics – in other words materialistic science – can ever encompass. In particular they believe that mental phenomena are ontologically irreducible to physics.

This controversy has been going on for a long, long while, and has for centuries attracted the attention of philosophical and scientific thinkers of the first order. Interestingly, although both sides often declare the intellectual bankruptcy of their opponents, neither view has emerged triumphant – a very telling fact, given the amount of effort that has been devoted to the problem. It would seem that the argument simply cannot be resolved at our present level of understanding.

Most scientists, unsurprisingly, are not dualists. Why should they be? Their inquiries, based on the physicalist assumption, have led to dazzling success, with the promise of much more on the way. Even in the most difficult areas – cosmology, fundamental physics, and the workings of the human mind – fantastic progress is being made.

This progress, which has resulted in an extraordinary transformation of human life in recent centuries as science has yielded one after another technological marvel and astonishing discovery, has led many a scientist to the assumption that physicalism is proven, that the debate is settled. And to be sure, there is no evidence that the physicalist assumption is wrong. Yes, there are still deep mysteries: the nature of time, the reasons for the values of the fundamental physical constants, and above all the relationship between our conscious minds and our bodies, but there is no reason to assume that such phenomena are intrinsically beyond the grasp of physics.

But the fact that there is no reason to assume that a proposition is false is by no means the same as having evidence that it is true. This doesn’t stop a lot of physicalist thinkers, though, from taking a contemptuous view of dualism. For example, here is a quote from Daniel Dennett, a leading materialist philosopher (this passage was also recently quoted by Dr. Vallicella on his website):

Dualism (the view that minds are composed of some nonphysical and utterly mysterious stuff) . . . [has]been relegated to the trash heap of history, along with alchemy and astrology. Unless you are also prepared to declare that the world is flat and the sun is a fiery chariot pulled by winged horses ”” unless, in other words, your defiance of modern science is quite complete ”” you won’t find any place to stand and fight for these obsolete ideas. (Kinds of Minds, Basic Books, 1996, p. 24)

This is pretty strong stuff. Anyone reading this who had no knowledge of the details of the ongoing debate would think that dualism had indeed been conclusively refuted. Indeed, my own intellectual upringing led me to think that was the case, and I spent much of my young adulthood utterly convinced that this was so. (I still think dualism is probably wrong, but that is a very different thing from believing that it is proven to be wrong.)

But there are many on the other side of the fence (where the philosophers outnumber the scientists) who take an equally dogmatic view. To them, it is simply obvious, somehow, that mental phenomena are ontologically distinct from, and irreducible to, the material world. In other words, despite the growing evidence of close bidirectional coupling between the observable state of the physical brain and our subjective experience – right down to being able to predictably induce emotions, memories, qualia, and so forth by stimulating tiny regions of tissue – they maintain that minds are at once irreducibly subjective, objectively real, and completely immaterial. How do they know this is so? Beyond rightly pointing out that physicalism is a philosophical preference, rather than a proven fact of the world, dualists often argue that the truth of their position is simply apparent : the primary experience, the ground of all other possible experiences a person can have, is the experience of one’s own consciousness, and – here’s where it gets a little tricky if you haven’t drunk the dualist Kool-Aid – it is just a brute fact of the world that such experiencing cannot possibly be built upon ordinary physics. The degree of confidence of those maintaining this assertion is often every bit as dogmatic and condescending as that of the physicalists. For example, one of the frequent commenters at Maverick Philosopher is a fellow named Dave Gudeman (aka Doc Rampage). Dave is obviously a very intelligent and well-read man, and a thoughtful commenter (I have added his site to my blogroll), but has such antipathy to the view I have been defending (I shall assume that it is not to me personally) that he responded to one remark of mine by saying “Drat. Malcolm actually has a good point,” apparently startled that a physicalist like me could get anything right. Here is an excerpt from a recent comment:

Frankly –and I don’t want to sound patronizing here, but– I suspect that you, like most physicalists, are laboring under the misconception that Bill discusses [in a recent post about Dennett]. You are thinking of the mental as being simply another physics, more tenuous, less accessible, maybe in a weird dimension somewhere.

But that is not what it is. The mental is nothing more than what it appears to be. Thoughts aren’t mental objects, with mental mass, produced from mental raw materials and moved by mental energy. They are simply what they are, and no more. When I say that a thought T is “about” object X, I don’t mean that there is some mysterious line of mental force connecting T with X. I just mean that T is about X.

Your scientific training has led you astray with the promise that everything can be fit into a clockwork world where everything is composed of smaller things and where every event has a cause based on masses and forces. Some things do not fit that model.

Notice that physicalism (in which mental phenomena are alleged to be thought of as some sort of matter “more tenuous” – a new one on me), is not a competing yet plausible model, but a “misconception”, and that those who lend credence to it have been “led astray”. Notice also the flat declarations that that “is not what it is,” and that “some things don’t fit that model.” How do we know this? Well, we just do.

To his credit, Dave says elsewhere that he is prepared to accept physicalism if reduction of the mental to the physical can be demonstrated. Given the remarks above, though, I wonder what would be a convincing demonstration. We’re working on it, in any case.

The dualist assumption, of course, raises some hard questions. One of the oldest asks how the immaterial mind can control the material body. What is the point of contact, and how is such interaction moderated? To the physicalist there is a serious problem here: if the mind is nonphysical, doesn’t its causal interaction with the physical world raise issues of conservation?

Dualists acknowledge that this is a serious problem, and to get around it they call into question physicalist assumptions about causality. Following Hume’s skeptical viewpoint, they ask how we know that our assumptions about causal relationships are correct. If event A is always followed by event B, and event B is always preceded by event A, we tend to assume that A causes B. But if this is not the case – if the regularities of the world are not causally determined, but are, rather, nothing more than contingent associations – in other words, if causality does not exist in the first place – then there need be no special exemption for mental-physical causality. Likewise, if such causality does not involve an actual transfer of energy, which physicists believe to be conserved, then there is no violation of physical laws. Dr. Vallicella has a cogent discussion of these views here.

But to the physicalist, all of this seems like special pleading. We have a model of causality (extended to include QM indeterminacy) that works very nicely, thank you, for all of the phenomena we can get our hands on, up to and including the workings of the brain. These workings, these unbelievably intricate electro-bio-chemical interactions taking place inside our skulls, are being shown in ever-increasing detail, and with growing predictive certainty, to map closely onto subjective mental experiences. Although there are still enormous gaps in our understanding, and perhaps entire categories of physical phenomena yet to be identified, there is every reason to be optimistic that the mind will one day cease to be a mystery.

That, at least, is my view. Though it is shared by the majority of neuroscientists and a good many philosophers, it may turn out to be mistaken. Nobody, repeat nobody, knows with certainty which of these competing viewpoints is right, or whether the truth is something as yet unimagined. So let’s all try to be civil, and get on with our work. There is much to do.