The Master and His Emissary: The Divided Brain and the Making of the Western World
Iain McGilchrist
2009
Yale University Press
New Haven and London
HB, 597
£25
9780300148787
I was not asked to write this review; I asked to be allowed to. I ordered my copy immediately after reading Mary Midgley's review1 in the Guardian and waited impatiently for it to arrive. When it did, I read it in every spare moment I had, and a lot I hadn't, ending up with underlinings and sometimes manic exclamation marks pencilled onto almost every page: 462 in all, not including another 123 of small-print notes and references. And that ‘pencilled’ (it dawned on me as I read) is important: pencil is inherently provisional, so it helps to keep the experience of the book alive. In other words, it makes at least an attempt to stop the excitement of first reading being grabbed and ossified by my left hemisphere.
Iain McGilchrist's qualifications for his massive undertaking are ideal, perhaps unique. A practising psychiatrist, once consultant and clinical director at the Maudsley Hospital, experimental neurophysiologist at the Johns Hopkins in Baltimore, ex-lecturer in English at Oxford University, Fellow of All Souls' on no fewer than three occasions, he is indeed the ‘Renaissance man’ so fitting to his theme. He begins by describing the range of techniques available to study the functioning of the brain, the way different areas ‘light up’ with different activities, and the way these areas are connected. Nor does he duck the limitations of these techniques. He notes therefore, among numerous surprising discoveries, that the great majority of inter-hemispheric connections in the corpus callosum are inhibitory. He then points out that split-brain patients (of whom he has had his share) hardly seem handicapped at all, and asks the pertinent question, ‘Why ever not?’.
His answer includes the idea that being able to model the outside world in two ways, both essential but so qualitatively different from each other as to be irreconcilable, conferred an evolutionary advantage on our remote ancestors. So natural selection led to the physical and functional separation of the hemispheres becoming more and more complete, and to their interconnections becoming more and more subtle — a ‘bridge that divides’. Thus our comprehension of the world begins in the right hemisphere with our apprehension of sensory input, and is passed to the left hemisphere for technical things like analysis, measurement, and codification, especially in language. But in the end the buck passes back to the right hemisphere for the synthesis on which we base our ideas and our actions. The point is that both sides are involved in everything, and the health of the system is dependent on the balance and the cooperation between the two. McGilchrist's essential message is that the right hemisphere is naturally the master, and the left, indispensable and clever as it may be, is the master's tool; in other words, his emissary. But in the story from Nietzsche which gives the book its title, the talented emissary usurps the wise master, and the results are disastrous.
In the second half of the book this fluctuating balance of power is shown to correspond, in a way which is quite wonderfully lucid and convincing, to a series of great cultural swings in the history of Western civilisation. From Heraclitus to Plato, from the Renaissance to the Reformation, from the Enlightenment to Romanticism, and so to Modernism, McGilchrist's grasp of this vast field, and the depth of his philosophical and artistic insight, is staggering, especially to someone who has just finished a 6-year Open University Humanities degree. To take just one tiny theme from this fabulous wealth of material: swings towards left-brain ascendancy led to the decapitation of statues of saints during the Reformation, to the decapitation of Kings during the French Revolution, and perhaps (and this is my own extension of the idea) to the emasculation of general practice in the 1990s. In every case the left brain only understood, and only attacked, the symbol, mistaking it entirely for the reality it represented.
AC Grayling, writing in the Literary Review2 challenges McGilchrist's thesis on two fronts: First he says that McGilchrist builds too much upon what is in fact a ‘slender state of [neurophysiological] knowledge’. I do not agree — I find the evidence cited in such detail extremely convincing. But it wouldn't really matter if it wasn't; McGilchrist makes it clear he is content for his thesis to be seen as a metaphor (see opposite). And in that case it is emphatically a metaphor which works. It underpins, validates, explains a whole slew of intuitions about general practice and life which I have felt and tried to express in (inevitably) inadequate words and which I know are widely shared. It is also a metaphor which fits in the most beautiful way to clarify our entire cultural history. It was the great physicist Paul Dirac who saw beauty as a hallmark of truth in science.
AC Grayling's second criticism concerns the section towards the end of the book (pages 428–434) which describes what a society which embodied the left hemisphere world view would tend to look like. It is a chilling catalogue of the things that most worry so many of us about the world today. But Grayling complains that this picture is not matched in the book by a description of what a right hemisphere world would look like — with its equally troubling superstition, arbitrary authority, religiosity, and so on. But the point Grayling misses is that everything McGilchrist says is about balance, and about the relationship between the worlds created by the two hemispheres. Indeed, it is precisely Grayling's assumption that this is a matter of one-or-the-other, either/or, which marks him so clearly as fixed, like so much of the official mindset today, in the left hemisphere trap. Here is McGilchrist's final paragraph:
‘The divided nature of our reality has been a consistent observation since humanity has been sufficiently self-conscious to reflect on it. [… He names a few key examples …] What all these point to is the fundamentally divided nature of mental experience. When one puts that together with the fact that the brain is divided into two relatively independent chunks which just happen to mirror the very dichotomies that are being pointed to — alienation versus engagement, abstraction versus incarnation, the categorical versus the unique, the general versus the particular, the part versus the whole, and so on — it seems like a metaphor that might have some literal truth. But if it turns out to be ‘just’ a metaphor, I will be content. I have a high regard for metaphor. It is how we come to understand the world.’
I think it is more than a metaphor. Time and again the insights it yields coincide with instincts that many of us share, but have difficulty expressing in words — the required currency of contemporary thought: above all the need to balance, in general practice perhaps more than in any other field, the rigidity of logic with the warmth of humanity. I know too well there will be many sceptics. I challenge them to read this book before dismissing what their left brain thinks it says.
- © British Journal of General Practice, 2010.
