Books >> THE BRAIN: The Last Frontier
Chapter 1 The Philosopher's Myth
On the contrary, it is impossible to obtain an adequate version of the laws for which we are looking unless the physical system is regarded as a whole. -M. PLANCK, 1931
Two former Nobel Prize laureates in physics were recently asked to guess what area of research would win the Nobel Prize for physics in the year 2000. Both of them, without prior consultation and with hardly a hesitation, said brain research. The human brain, they concluded, is our ultimate intellectual challenge in the last quarter of the twentieth century.
There is a double irony in the choice of the brain as an area of research worthy of Nobel Prizes in physics. For one thing, physics is one of the "hard sciences," a model of the "objective" view of the world. Brain research, in contrast, has been modeled on biology, a "softer," more fuzzy discipline where disagreement abounds. (Articles are still appearing from time to time attempting to disprove even such well-established biological principles as evolution.)
Second, brain research is taken up with questions even more fundamental than those which challenge the theoretical physicists:
"How do we know what we know?" "What is the real world?" "Who am I?" Until very recently such questions were referred to theologians or philosophers, whose speculations provided the foundations for complicated and impressive philosophical systems. But today, philosophy and theology exert a far less compelling influence on our lives. When was the last time you saw a philosopher or theologian on a late-night talk show? And how many of us can get out more than a few mumbled generalizations about the major philosophical thinkers of the last five hundred years?
With the collapse of philosophy and theology as major influences on our lives, questions such as "How do we know what we know?" or the ringing "What is truth?" have remained unanswered and, even, largely unasked. In their place, we've focused on questions of a more "practical" nature. Food, energy supplies, pollution, crowding, the breakdown of needed social services-these are some of the areas which have received and continue to receive the most attention. Already some of them are reaching crisis proportions.
The world's population, for instance, is expected to double in the next thirty to forty years. In addition, population growth now indicates that each doubling of the population will take place in half the previous time. Instead of thirty to forty years, we move to fifteen to twenty, with our children witnessing a population doubling spaced over one or two decades.
Realizations such as this tend to encourage even greater emphasis on the external environment. Birth-control techniques are expanded and, at least in India , sterilization procedures are forced on groups of citizens without their consent. Energy policies are formulated which concentrate on how best to cope with a dwindling supply of oil and energy reserves. Everywhere we are concerned with how we manipulate or manage one crisis after another.
In recent years, however, we've experienced a change in the types of crises that immediately threaten us. No one can now board an airplane without a gnawing fear of a hijacking or a bombing. In less than five years, terrorism has become one of the most decisive influences in our lives. It is also one of the most conspicuous examples of an internal as well as an external threat to our continued existence.
One understandable response to all of this is to turn to the behavioral sciences to provide the answers to the questions that plague us. Although initially appealing, this suggestion overlooks the rather poor track record that the behavioral sciences have shown in the past. Different authorities hold radically different views on why we act the way we do. Things have now become so complicated, in fact, that psychologists trained in one orientation are often unable to agree with other psychologists on such basic concepts as what psychology is about. Those trained in behavioral methods, for instance, operate as if consciousness doesn't exist, while scoffing at their counterparts who value and rely upon subjective experiences.
In the last several years, a new field has emerged which may offer us a better means of understanding and controlling some of our internal and external threats. Known as psychobiology, this new discipline is a combination of the behavioral sciences and the brain sciences. It differs from other studies of behavior in some of its initial assumptions. While the working of the brain is often peripheral to most theories of psychology, psychobiology depends primarily on what we have learned about the brain and how it works. The emphasis is on how the brain influences our perceptions of the world, how we know ourselves, the nature of reality-in essence, the questions we mentioned earlier as formerly asked by philosophers and theologians.
Basically, psychobiology is concerned with the mind's attempt to know itself through the study of the brain. Today we accept as a truism that the brain is the physical basis of the mind, although .this is not quite the same thing as stating that the brain is the ,mind.
Throughout history, almost every major part of the body has been credited at one time or another as the seat of the mind or the soul. In civilizations such as the Sumerian and the Assyrian, the liver was considered the repository of the soul and the physical basis for the personality. To Aristotle, the heart was the central ,organ, while the brain existed as a sort of cooling mechanism for the blood as it left the heart. This view of the importance of the heart survives today in our popular images of "heartbreak" as a description of the effect of unrequited love, and "bleeding hearts" as a contemptuous term for people who are ruled by sympathy and sentimentalism.
Today we look to the brain rather than to the heart for an understanding of the mind. While this is largely an advance over the superstition and ignorance of the past, it presents us immediately with some rather knotty problems. The first of these is an organizational one.
The number of neurons in the human brain is almost equal to the number of stars in our Milky Way-over fifteen billion. What are the relationships of the nerve cells to each other? To understand the brain, is it necessary to deal with all possible interactions between nerve cells? or with only some of them? Put another way, What level of organization offers the best hope toward understanding how our brain works?
One of the stumbling blocks to understanding the brain can be traced, I believe, to selection of the wrong level of organization. Let me illustrate what I mean.
Forget about the fifteen-billion figure I gave you a moment ago, because that is a staggering number to deal with. Instead, let's work with something more manageable: the number of people presently inhabiting the earth. Imagine each person with a telephone capable of calling any other person in the world. In addition, assume that in our model the important information about people's activities and behavior is always discussed over the telephone. Our job will be to keep track of all the calls and to correlate telephone calls with behavior. Some of this may be very easy, as when a person in London calls a friend in New York and invites him to come over for a week. Within a day or two of such a call, the friend in New York can be observed carrying his bags while leaving his apartment on the way to the airport. At such a time we may feel quite confident that our telephone monitoring system is working well and giving us an accurate and useful correlation between person-to-person communication and behavior. As the number of people increases, however, our method will soon break down. Imagine all the telephone calls we would have to monitor to enable us to predict the identity of the passenger list of a jumbo jet leaving for Athens six months from now. Or imagine the number of telephone calls that would be needed to estimate the population of Schenectady , New York , between the years 1979 and 1980.
Perhaps you think such a task could be handled very well by computers. To see why this is impossible, let's simplify the situation a bit by reducing the number of variables from fifteen billion to a mere thirty-two. Thirty-two just happens to be the maximum number of pieces we can play on a chessboard at anyone time. At a typical point in the game, thirty permissible moves are open to each player. If it's white's turn to play, for instance, each of his thirty moves can be countered by thirty moves on the part of black, which leads to about one thousand variations at the end of one round of play.
With white's next move and black's response, everything is computed again, yielding one million positions. By the third move we're at one billion, and so on. In a very short time the number of possible calculations becomes, for all practical purposes, infinite.
In the case of our telephone system we are helped by the fact that every person isn't likely to call everyone in the world. Barriers of language, common interest, and acquaintance limit somewhat the number of possible calls. In chess a similar situation exists, since not every move is equally good and some are downright disastrous, leading to a quick checkmate. In the brain, however, we have no rules that would enable us to know beforehand with absolute certainty whether one brain cell is influencing the activity of another one. This gets us back to the stars-in-the-galaxy-neurons-in-the-brain situation, which represents a level of complexity no human mind or computer can ever be prepared to deal with. In short, if we focus our attention on the neurons and their interconnections, we're selecting a level of organization that can never satisfy our efforts at understanding.
On the other hand, if the level chosen is too sweeping, we come out with generalizations that are useless. "The brain works as an information-processing system" is intended to be informative, but it really doesn't tell us anything at all. The key is to focus on the correct level of organization.
Another related problem in our attempts to understand brain functioning is a more philosophical one. We live in a world of things. Our perceptions are geared to encountering objects and people who change very little from day to day. "A rose is a rose is a rose," according to Gertrude Stein, and she might have selected, with equal validity, anyone of the tens of thousands of objects and people we encounter every day.
The alternative view, never a popular one, holds that the world consists of processes and that what we perceive around us are only frames in a movie. The Greek philosopher Heraclitus said you never step into the same river twice, since the water continues to flow and tomorrow you will encounter different water than today.
Things are always in a process of change, like a flame converting combustible substances into heat, light, and hot gases. A fire is not a thing but a process of combustion.
Modem physics is very much a process science and poses the greatest challenge to our things view of the universe. Quarks, black holes, and particles of antimatter are neither accessible to our direct experience nor can they be considered fixed entities. Despite this, each of these strange-sounding words has already become part of our everyday vocabulary. With the discovery of the atom and the subsequent exploration of the inner world of subatomic physics, the mechanistic things view of the universe began to crumble. Even before that, nineteenth-century scientists demonstrated that the movement of a magnet near a coil of copper created electrical energy described by the experimenters as a "disturbance" or a "condition" rather than a thing. By the third decade of this century the mechanistic things view of space and time yielded to the concept of a space-time continuum. All measurements involving space and time thus lost any absolute significance.
Today, physics is the study of interactive processes rather than discrete particles. In such a model the atom is not solid but a tiny universe of energy, with the nucleus and its orbiting charges separated by vast space. H the actual mass of our brain were condensed minus that energy space, it would occupy an area smaller than the head of a pin.
My purpose in introducing physics at this point is to contrast it with our approach to the study of the brain. While physics has become very much a process science, our ways of thinking about the brain have been locked into looking at the brain as a thing. This creates some immediate, and occasionally subtle, difficulties.
Is the brain the mind? This question at first seems sensible and capable of verification. It has in fact stimulated the imaginations of scientists and philosophers for centuries. Some now feel that the answer is obvious: The mind is nothing but the action of the brain and is a meaningless concept without reference to a brain. As a neurologist, I felt for the longest time that this view was correct.
But the question is actually a trick, of the "Have you stopped beating your wife?" type, where either a yes or no carries with it undesirable implications. In both instances, the proper response is to focus on the question itself and show how the form of the question results in a "loaded dice" situation.
The philosopher Gilbert Ryle once described the mind-brain dilemma as a "philosopher's myth" based on what he called a "category mistake." Imagine an eight-year-old boy taking his first trip to Washington , D.C. He's been told in school that Washington is the seat of the nation's government. On the first day, the boy visits Congress. On day two, he takes a tour of the White House. On the third day, he's shown the Supreme Court building. At this point the boy seems puzzled and asks: "But where is the government? I've seen Congress, the White House, and the Supreme Court, but I still "haven't seen the government." Ryle would explain our young man's puzzlement as resulting from a category mistake. Congress, the White House, and the Supreme Court are things-at least each of them can be physically located in space and time. The government, in contrast, is quite another category altogether. It is, in fact, a supercategory which describes the interactions of the other three.
In a similar manner the brain can be dissected, electrically stimulated, or even placed in a blender and homogenized to a few ounces of froth. The mind, however, remains as elusive as the "government" our eight-year-old was trying to find in Washington .
When we're trying to relate the brain to the mind, we're dealing with a category mistake, since the brain is best conceived as a process rather than a three-pound lump of protoplasm. Think of the problems that resulted from our telephone model of human communication, and that model involved only the population of the earth instead of the fifteen-billion interactions that are possible within our heads! Understanding ultimately depends on our ability to concentrate on the process. Once a process is understood, the actual mechanisms of how it is carried out are of less importance. To correlate brain with mind, or vice versa, is a category mistake that insists on equating two different processes. The trick is to exercise care in distinguishing a prerequisite from a cause.
On any given morning, the Los Angeles Freeway is a prerequisite for thousands of commuters getting to work. It is hardly a causative explanation, however, of how a particular commuter, say a stockbroker, can be found at nine o'clock propping his feet on his desk while perusing a list of client telephone numbers.
The question "Is the brain a sufficient explanation for the mind?" was anticipated by the biologist Sir Julian Huxley: "The brain alone is not responsible for mind, even though it is a necessary organ for its manifestation. Indeed, an isolated brain is a piece of biological nonsense as meaningless as an isolated individual." For the sake of argument, however, let's assume that we've reached a point where every mental event, every product of "mind," can be correlated with something going on within our brain. This is yielding a lot, incidentally, since we're not anywhere near the point of making such correlations. But for the moment, let's imagine it's possible that we can. Since we think of the world as being governed by physical laws, the explanation for such a correlation seems obvious: The brain events are the cause of the mental phenomenon of thinking, perception, whatever. In essence, the mind is dependent on the brain. But logically, isn't just the opposite explanation-The brain is dependent on the mind-equally likely? From a strictly logical point of view, this is an equally valid stance to take, given the postulated parallel between mental events and brain processes.
Despite the seeming logic of all this, most people have a terribly strong hunch that such a view ultimately doesn't make sense. The mind created the brain? I don't believe it for an instant, and I hope you don't. I am only bringing it up to show why the mind-brain controversy may never be resolved. Category mistakes result from our equating the brain and mind as things when they are actually processes. This confusion immediately leads to mistakes in the way we think about behavior. Naturally, if we start from wrong premises, we are going to end up with theories that are useless and don't work. Let's take a moment to consider some of the ways we traditionally "explain behavior." | |
