Matter of Mind: A neurologist鈥檚 view of brain-behaviour relationships by Kenneth M Heilman, Oxford, 拢29.95, ISBN 0195144902
Consciousness in Four Dimensions: Biological relativity and the origins of thought by Richard M Pico, McGraw Hill, $29.95, ISBN 0071354999
Thinking About Consciousness by David Papineau, Oxford, 拢25, ISBN 0199243824
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The Way we Think: Conceptual blending and the mind鈥檚 hidden complexities by Gilles Fauconnier and Mark Turner, Basic Books, $30, ISBN 046508785X
A Brain for All Seasons: Human evolution and abrupt climate change by William H Calvin, Chicago, $25/拢16, ISBN 0226092011
The Illusion of Conscious Will by Daniel M Wegner, MIT Press, 拢23.95, ISBN 0262232227
What Makes Us Think? A neuroscientist and a philosopher argue about ethics, human nature and the brain by Jean-Pierre Changeux and Paul Ricoeur, Princeton, 拢12.95, ISBN 0691092850
NEWLY armed with a doctorate, I became fascinated by the possibility of researching memory. My boss 鈥� a Nobel laureate 鈥� objected strongly. Back then, this was no subject for sensible biochemists to poke their noses into. Today the molecular biology of memory is a hot topic.
Only a few years ago, I heard a Harvard neurophysiologist describe consciousness as a CLM: a career-limiting move. Yet now we are drowning in books, journals and conferences, and I can鈥檛 help sympathising with my old professor. Is all this activity anything more than neurobiologists feeling a fashionable urge to poke their noses into yet another once taboo topic?
First there is the small problem of definition. To many neuroscientists it is quite straightforward: being conscious is the reverse of being unconscious or asleep. It is to be aware of and, to a degree, in control of one鈥檚 thoughts, intentions and actions.
Philosophers in the Anglo-American tradition puzzle over the subjectivity of consciousness, which makes it private and personal, and worry about how this subjectivity may be related to the objective brain states that neurobiologists can measure. Psychoanalysts, in contrast, speak of 鈥渢he unconscious鈥� as providing the bases 鈥� to which we do not have direct access 鈥� for thoughts and actions.
For all of these, consciousness is something 鈥渂elonging to鈥� an individual, and caused by 鈥� or at least related in some way 鈥� to what is going on inside that person鈥檚 head.
Sociologists, however, refer to consciousness in quite another sense: they speak of class, race or gender consciousness. Here 鈥渃onsciousness鈥� is no longer the private property of an individual but the expression of a relationship between that person and the surrounding social and cultural world. To seek the causes, or even the correlates, of this sort of consciousness inside one head would be absurd.
For several of the authors in this current spate of books, such issues are mere quibbles. Kenneth Helman is a no-nonsense neurologist. The mind, he tells us briskly, is the product of the brain鈥檚 activities. He takes us on a sort of Grand Ward Round of patients he has studied over the years, who suffered various forms of brain damage and consequent lesions of thought, emotion or action. This is the territory of Oliver Sacks鈥檚 The Man Who Mistook His Wife for a Hat, without the elegance of the prose-poetry.
Richard Pico is an ex-psychiatrist and now president of a biotech consulting company, and he has a Big Idea. Einsteinian relativity requires that we think in four dimensions: three of space and one of time. Biological systems, too, are four-dimensional. (I don鈥檛 quite understand why we need to invoke Einstein to appreciate this, but there you go.) Pico gives us a quick and helpful tour through the origin of life, brain structure and evolution. Then 鈥� hey! 鈥� the Big Idea is delivered: consciousness, it seems, is the product of neural modules in the prefrontal cortex. No time here for the philosophical subtleties through which David Papineau edges towards a rather more sophisticated materialism.
If consciousness is a uniquely human property, then how and why might it have emerged? What evolutionary function might it serve?
Judging by the fossil record, human cranial capacity hasn鈥檛 altered much in the past 300,000 years. Yet we see dramatic changes in the quality of artefacts. Cave paintings appeared about 50,000 years ago. Could these be linked to the development of language and consciousness? The discovery, or at least suggestions, of much older paintings and of 250,000-year-old pigments does put this account into some difficulty 鈥� but it鈥檚 not dead or buried yet.
Cognitive scientists Fauconnier and Turner analyse at length the structural complexities of human language, with its rich blending of concepts and categories. They see its evolution as a key event in human history.
Neuroscientist turned science writer William Calvin makes an ambitious attempt to link the origins of language and consciousness to evolutionary crises resulting from the rapid flipping of temperature that occurred as ice ages set in 鈥� at a key moment in human expansion out of Africa.
Calvin raises urgent questions about the implications of the current phase of global warming. His account suffers somewhat from a rather arch format 鈥� based on the pretence that it is an e-tutorial given on an extended tour of world heritage sites 鈥� but has important messages, both for the theory of consciousness and the practice of survival, nonetheless.
But what if consciousness is an illusion? Some years ago physiologist Benjamin Libet conducted a much-cited experiment which claimed to show that conscious awareness of the intent to perform an action actually occurred some fraction of a second after the neurophysiological events leading to that action. I have some reservations about the interpretation of Libet鈥檚 results, but they form one of the pillars of psychologist Daniel Wegener鈥檚 argument that consciousness is indeed an illusion, and that what really matters is what is happening in the brain.
This puts us back in the Victorian world of Thomas Huxley, who compared consciousness (or 鈥渇ree will鈥�) to the whistle on a steam train. He declared it to be an 鈥渆piphenomenon鈥� 鈥� a side effect of something causative.
Read Papineau鈥檚 book to deal with this argument. Objections such as his don鈥檛 prevent Wegener鈥檚 book being rich with experimental data and a fun read, especially in its accounts of automatism and hypnotism. And the punchline is: if consciousness is an illusion, it nonetheless has a function 鈥� that of providing the emotion of authorship, of being in control.
Which brings me at last to the real joy of the discussion between molecular neurobiologist Jean-Pierre Changeux and Paul Ricoeur, who is an anthropologist and a hermeneutic philopsopher 鈥� one concerned with interpretation. First published several years ago in French, this debate has a richness that sometimes makes me despair of the aridities of classical Anglo-American cognitive psychology and philosophy of mind.
I empathise with Changeux, who as an experimenter is one of neuroscience鈥檚 great reductionists, but is wise enough to know that outside the lab reductionism is not enough. He exposes the findings of modern neuroscience 鈥� at all levels from the molecular to systems theory 鈥� to the scrutiny of his opponent. Ricoeur replies that, however valid these neuroscientific stories may be within their own context, they have nothing to say about the experience or relevance of conscious thought, of human agency, of ethics and of moral responsibility.
Biologists may feel that Ricoeur is playing, if not devil鈥檚, then angel鈥檚 advocate here. Maybe he is: but these are some of the questions neuroscience has to confront if it continues to poke its nose into matters hitherto the concerns of other sciences.