A lively discussion has been going on over at Bill Vallicella’s website. I seem to be spending so much time over there, in such engaging company, that I am getting very little done in here!
One of the topics we’ve been grappling with is the physicalist view of the mind. As you might have guessed from previous posts, I hold the view that our minds are entirely grounded in the physical world: that all of our thoughts, memories, fears, imaginings, etc. – in short, our inner lives – are the result of the activity of our physical bodies, in particular our nervous systems. We are a long way from completing the scientific program that will exhaustively map subjective experience onto objectively measurable physical states and transactions, but I do believe, along with most scientists studying the problem, that the idea is sound, and the goal attainable, in principle at least. But this view, all but hegemonic among research scientists, has met considerable resistance in the philosophical community. A recent posting at Dr. Vallicella’s site sums it up:
Marvelously complex as it is, the brain is just another chunk of the physical world. Study it till doomsday with the most sophisticated instruments, map every cubic millimeter of it, establish detailed correlations between brain regions and types of conscious phenomena — and what do you accomplish? You learn more and more about a highly complex piece of meat.
In other words, one might exhaustively map the entire state of the human body, all the way down to the patterns of neural activity in the brain, and still have some ineffable thing left over. For example, given the technology for a full neural-state scan, we might study a subject, and be able to declare with certainty that now she is thinking, say, of a piece by Brahms, and now she is remembering that she left the light on at home, and furthermore, if we excite this glial bundle right here she will suddenly feel a sense of humorous irony, and will laugh a wistful laugh, while if we stimulate this neuron over here she will hear a distant bell ringing – but even if we can do all of that with perfect reliablity, still something will be left out. That something is usually declared to be the subject’s inner experience, what it is like to be that person: the way the colors look, the way the music sounds, and so on. These subjective experiences are referred to as qualia (KWAH-lee-ah), and are considered by some to be inaccessible to any third party, and to be utterly irreducible to any physical description. In other words, there is the physical stuff of the world – our bodies – and then there is this other Thing: as real as can be – what could be realer than our own experiences? – but having no objective existence. Meat and Mind. This is called “dualism”, and it is an idea that goes a long way back.
Dualism is very tempting – it does seem that our mental states are of a very different quality than anything else in the world. They lack the permanance of physical objects, and unlike anything else we know of, they can be directly perceived only by one person. It is easy to imagine that they are separate, somehow, from the coarse matter of the world. But there are difficulties with this idea, foremost of which is that of understanding how a nonmaterial entity can get a grip on ordinary matter. If the actions of my body are driven in an uncontroversial way by my nervous system, then how does the immaterial Mind, in turn, drive the nervous system? What is the point of contact? How can non-material mental states drive the body into correlated physical states? How can a presumably undetectable non-physical entity do this without, for example, violating physical conservation principles? Likewise, how can a “quale” (that’s KWAH-lay, singular of “qualia”) have a purely non-physical existence? This seems less problematic until one realizes that qualia are easily connected to macroscopic causal chains in the physical world, as, for example, when I stop my car upon experiencing the “redness” of a traffic signal. There aren’t many exits here. One is simply to insist, on intuitive grounds, that our minds simply can’t be grounded in material processes, because it should be obvious that material processes just can’t produce minds. This is the bias represented in the quote above; implicit in the statement is the conviction that learning “more and more about a highly complex piece of meat” will never get you any closer to Mind, even though the particular piece of meat in question is no ordinary skirt-steak, but rather the most complex object, as far as we know, in the entire Universe.
Another way out is “epiphenomenalism”. This is a word that is used in two different ways, and sometimes the confusion is exploited by using it both ways in the same argument. Here are the two meanings of “epiphenomenon”, one used by scientists generally (in particular evolutionary theorists), and one used in a very strict sense by philosophers :
In the looser sense, an epiphenomenon is a nonfunctional trait that rides along with some useful or adaptive behavior. Daniel Dennett [Consciousness Explained, pp 401-402] gives the examples of the hum created by a computer, or the shadow you cast on the counter as you make a cup of coffee. Neither hum nor shadow serves any function related to the purpose at hand. To an evolutionary biologist, these epiphenomena are adaptively neutral traits that either ride along simply because there is no selection pressure against them, or because they are an inevitable but non-functional adjunct to some selected feature (Gould famously called such things “spandrels”). Epiphenomena like these, while having no bearing on the feature or function to which they are related, still have an obvious physicality – one can make physical recordings of the computer’s hum, measure the cooling effect of the shadow, etc. There is no room for a non-physical Mind here.
The stricter meaning of the word is that something is an epiphenomenon if it is caused by some phenmomenon in the physical world, but itself has no effect on the world. Such an entity is utterly undetectable by any physical means, and can have no influence whatsoever on the course of the world’s events. Yes, qualia could be of this nature, but then you would never be able to tell anyone about them, act on their content, or, as Dennett points out, act differently in any way than you would if you didn’t have them. This is obviously rather unsatisfactory as well, but it is taken up as a last resort by those who need to carve out a special place for the subjectivity of our experience: our qualia are quite real, and quite non-physical, but do not interact causally with our physical selves at all – such states are instead simply correlated with the physical activity of the brain. This seems like a particularly bleak view – our minds as feckless epiphenomenal ghosts, trapped in our bodily vehicles with no access to the controls. The world would be no different if we didn’t have them at all. And it is hard to argue convincingly that something like that even exists.
One way out is to see the brain as a purely physical system, driven into “reactive states” by the interaction of incoming sensory data with the brain’s previous state. Our awareness of “qualia” would then be detectable, in principle, by a complete analysis and understanding of the current reactive state of the brain. This leaves no room for the mysterious something “extra”, something transcendantly non-physical, that dualists are fighting for, but it seems to me to be the only model that plausibly accounts for the mounting neurological evidence of extremely tight coupling between the physical and the mental.