Where in the Brain is the Mind

The basis of consciousness is, I would submit, the most fascinating question we have ever tried to answer. To a first approximation, the answer is straightforward: it's the brain, stupid. The brain is what makes us think, talk, and be self-aware. If the brain is destroyed, one ceases to exist as a person, even though the rest of the body could go on living. For example, sometimes the brain can be so badly damaged by hemorrhage or injury that its functions are irreversibly lost; such a person becomes "brain-dead", which in legal terms means dead, even though the heart may continue to beat and the remaining organs continue to function well enough that they can be transplanted into other people. But what exactly is it about the brain that generates consciousness? Where in the brain, in other words, is the mind?

First, definitions. What exactly does one mean by 'consciousness'? To quote Webster's, it is "to be aware of one's own existence." I think that's a very good definition but, as with any complex idea symbolized by a single word, any definitions of the term will suffer from being incredibly deceptive. It's an easy concept to grasp when applied to awake, rational humans, but becomes problematic when extended to other forms of life (e.g., are dogs conscious?) or even to humans in altered mental states (e.g., sleep or madness). I think the true definition of consciousness might be concealed in the question of whether animals are conscious or not. I don't think they are, but it's a particularly thorny issue. After all, can anyone really say what it is exactly that differentiates us from other animals? Oh sure, a human can write a book and an animal can't; a human can design a building and an animal can't; a human can play chess and an animal can't. But is the difference merely one of degree (quantitative) or more fundamental (qualitative)? Do we possess some unique quality relating to our sense of being self-aware that non-human life forms do not possess? I believe the answer is that we do and, although I can define it no better for you, this is precisely what I mean when I use the term 'consciousness'. In this respect, consciousness is a bit like pornography: hard to define, but you know it when you see it.

Contemporary science has its roots in reductionism, so the prevalent expectation is that consciousness - the generation of self-awareness by the human brain - can be explained in terms of physical laws. Much effort, therefore, has been and continues to be devoted to the search for the biological, chemical and physical correlates of consciousness and its component mental functions such as thought, cognition and emotion. The Congress of the United States has declared the 1990s the 'decade of the brain'; the neuroscience literature is multiplying exponentially; humanity has set its sights on the ultimate quest of all, the holy grail of all intellectual pursuit: the science of consciousness. The brain has set out to understand the brain. It's all very grand, I realize, but the truth is we haven't gotten very far. In fact, whatever we do know about the basis of consciousness at this point remains insufficient to produce any hyoptheses that can be tested by experiment. Forced technical sophistry in the field notwithstanding, the most important question about the basis of consciousness continues to be whether the question is answerable at all, i.e. is consciousness natural or supernatural? Is there a soul, or is it all just chemicals?

The notion of a human soul is attractive in many ways. It's an intuitive concept: consciousness as a supernatural entity that represents our thinking and feeling essence in some unknowable way that cannot be understood in mechanistic terms. The idea is popular and widely espoused. It happens to be the position of many of our religions, monotheistic and otherwise, and is thus commonly part of peoples' personal belief systems. But its popularity also lies, I think, in its capacity to reinforce our innate sense of human uniqueness and superiority. The soul as ultimate existence elevates us above states of matter and promises immortality. After all, just as no 19th century person wanted to hear from Darwin that their ancestors were apes, no 20th century person wants to hear from modern neuroscience that their thoughts and feelings are the result of nothing more than particles of matter arranged in the right configuration. It's humbling, even insulting. Moreover, if there's no supernatural soul, what happens when you die? Does it all just go dark, poof, nothing ? This is probably the most important reason why the soul lives as an idea: because human existence must transcend death for this life to make sense to us. I happen to think that all that's OK, however, although admittedly only so long as we're not talking specifics. Meaning, I recognize it's an idea we must accept on faith rather than on the basis of any rational or empirical details. But see it another way. To paraphrase the scientific philosopher Karl Popper, theories cannot be validated, only disproved; so I submit to you, so long as the idea of a human soul is not disproved by rational experiment or argument, who's to say it's not true ?

Despite the wide appeal of the supernatural soul as an explanation for human consciousness, however, I think that anyone with a modern education can perhaps also see how this idea can seem to be the most fragile, unsubstantiated and flimsiest of notions, personal religious belief notwithstanding. Let's say you're the most rigorous empiricist who only accepts proven, demonstrated explanations. How can you possibly accept the existence of something that is undetectable by any of our biological senses or technological instruments ? You can't see, touch, smell, taste or hear it, it won't deflect a meter needle, or an oscilloscope beam, and you can't capture it on photographic plate or X-ray film. If you try to figure out the problem of consciousness empirically, therefore, you must work with what you have, and what you have are the laws of physics and the evidence that the brain is the organ of the mind, the seat of consciousness. This, then, is the modern position: the conceptual opposite of the idea of a 'soul' or 'spirit', it is the notion that consciousness, far from being something supernatural, is fully within the realm of physics and chemistry and can (eventually) be explained in terms of physical principles through a rational analysis of the brain's structure and function. On first pass, given the scientific knowledge explosion, this idea of a physical basis of consciousness also seems to have intuitive appeal. After all, we have discovered and characterized all kinds of impressive facts about the human brain and it is tempting to speculate that all this novel information will imminently coalesce into some compelling, mechanistic explanation of how we think. But here's the problem: it's not happening. The human brain is turning out to be complex beyond our imagination. And don't let the spate of recent books on the subject fool you. The arguments and ideas put forward by luminaries like Francis Crick (The Astonishing Hypothesis), Antonio Damasio (The Emotional Brain) and Daniel Dennett (Consciousness Explained, Kinds of Minds) are just sophisticated speculation. In fact, if one is really rigorous about it, we can't even begin to prove that life itself, even in it's simplest forms, is reducible to physics and chemistry, let alone the lofty phenomenon of human consciousness. I say this because no one can yet pull chemicals off a shelf and mix them together to form a living cell. To me, that is the ultimate test of biological reductionism: start with physics and chemistry and produce biology. Despite dramatic advances in biological knowledge, this hasn't happened yet and I don't foresee it any time soon, if ever. When it happens, let me know. Until then, I have to say that the hope of explaining consciousness in physical terms is little more than a pipe dream.

As a footnote to this, one should also consider the question of computers and artifical intelligence (AI). Advances in computer science and technology have held the promise to some that important insights into human thought and consciousness can come from this field. But consciousness is a biological process and I find it difficult to imagine how computers will help us model it when we don't even know what the basic alphabet of consciousness is. As an example, how can you understand chemical reactions without knowing atomic theory ? I think consciousness remains so utterly perplexing to us because we haven't yet developed its "atomic-theory"-equivalent. As for artificial intelligence, it's neither. AI theory has made important contributions in pure computational processing, but the idea that AI can somehow produce computational intelligence to rival human self-awareness is science fiction of the most implausible kind. One gets into nebulous concepts here, like what does it really mean to be aware and what does it really mean to know something. Here's how I see it. Even if a computer passes the test of consciousness proposed by the English mathematician Alan Turing (i.e., interacts with us in a way indistinguishable from human intellect), it still has to contend with John Searle's Chinese Room argument before it can be considered 'conscious'. The Chinese Room argument is a thought experiment that goes as follows. A man who knows no Chinese is isolated in a room and provided with the rules of manipulating the symbols of the Chinese language without being told their meaning. He is then given something written in Chinese, to which he responds by consulting his rulebook and generating the appropriate symbols. To an outsider, it seems that the man in the room can communicate in Chinese, but does he really know Chinese?

Since, given two opposing positions, truth often tends to be in the middle, my personal view is that human consciousness is not quite supernatural, but not quite within the limits of standard physical laws either; rather, it is something novel and complex, existing at the fringes of physical reality, yet nevertheless understandable in a mechanistic sense. This is not an original view and, for those interested, receives excellent treatment in works by Roger Penrose (The Emperor's New Mind, Shadows of the Mind) and John Searle (In Search of the Mind), who stress the complexity of consciousness rather than its knowability.

In 17th-century France, Rene Descartes had the very novel insight of viewing biological organisms as just any other machine. This was clearly a landmark advance for much of biology, but the intellectual leap had obvious limits when applied to the study of man. Like other animals, man too must be a machine, Descartes thought, but what manner of machine could possibly generate love, art, poetry, music, science? Hence the Cartesian pronunciation that there must be a ghost in the machine. In a sense, the boundary limits in the study of human consciousness haven't really shifted since then. Is there a soul or isn't there? Is consciousness beyond matter and therefore beyond the known laws of physics? Is it at least beyond biology, meaning can it exist without amino acids, sugars, fats and DNA ? And if so, does this mean that the human self survives death? I realize there are no testable hypotheses here, so who knows. But, anyhow, back to Descartes. Descartes used to wonder if everything that he was able to know about the world was no more than an illusion, a kind of magical apparition conjured up by a devious and powerful sorcerer. He concluded that an illusionist could trick him into believing everything, except the fact of his own existence. In other words, no one could trick Descartes into believing that he existed if, in fact, he didn't. Hence, cogito ergo sum (I think, therefore I am). So in 1641 Descartes had settled the question of whether we existed or not. But the next logical leap - the basis of that existence - remains somewhere in the future, perhaps even the perpetual future.