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Iain McGilchrist

The Master and His Emissary

Our two brain hemispheres are opponent processors:
what does that imply for us and our culture? 


Three-dimensional rendering of the inferior surface of the brain, derived from in vivo MRI scanning. There are obvious asymmetries in the anatomy of the two hemispheres - protrusions of the hemispheres, (anteriorly and posteriorly), differences in the widths of the frontal (F) and occipital (O) lobes, and a twisting (torque) effect.

This is a story about ourselves and the world, and about how we got to be where we are now. While much of it is about the structure of the human brain – the place where mind meets matter – ultimately it is an attempt to understand the structure of the world that the brain has in part created. Whatever the relationship between consciousness and the brain – unless the brain plays no role in bringing the world as we experience it into being, a position that must have few adherents – its structure has to be significant. It might even give us clues to understanding the structure of the world it mediates, the world we know. So, to ask a very simple question, why is the brain so clearly and profoundly divided? Why, for that matter, are the two cerebral hemispheres asymmetrical? Do they really differ in any important sense? If so, in what way?

The subject of hemisphere differences has a poor track record, discouraging to those who wish to be sure that they are not going to make fools of themselves in the long run. Views on the matter have gone through a number of phases since it was first noticed in the mid-nineteenth century that the hemispheres were not identical, and that there seemed to be a clear asymmetry of function related to language, favouring the left hemisphere. At first, it was believed that, apart from each hemisphere obviously having sensory and motor responsibility for, and control of, the opposite (or ‘contra-lateral’) side of the body, language was the defining difference, the main specific task of the left hemisphere. The right hemisphere was considered to be essentially ‘silent’. Then it was discovered that, after all, the right hemisphere appeared better equipped than the left hemisphere to handle visual imagery, and this was accepted as the particular contribution it made, its equivalent to language: words in the left hemisphere, pictures in the right. But that, too, proved unsatisfactory. Both hemispheres, it is now clear, can deal with either kind of material, words or images, in different ways.

This is hardly surprising, given the set of beliefs about the differences between the hemispheres which has passed into the popular consciousness. These beliefs could, without much violence to the facts, be characterised as versions of the idea that the left hemisphere is somehow gritty, rational, realistic but dull, and the right hemisphere airy-fairy and impressionistic, but creative and exciting. In reality, both hemispheres are crucially involved in reason, just as they are in language; both hemispheres play their part in creativity. Perhaps the most absurd of these popular misconceptions is that the left hemisphere, hard-nosed and logical, is somehow male, and the right hemisphere, dreamy and sensitive, is somehow female... Discouraged by this kind of popular travesty, neuroscience has returned to the necessary and unimpeachable business of amassing findings, and has largely given up the attempt to make sense of the findings, once amassed, in any larger context.

Nonetheless it does not seem to me likely that the ways in which the hemispheres differ are simply random, dictated by purely contingent factors such as the need for space, or the utility of dividing labour, implying that it would work just as well if the various specific brain activities were swapped around between hemispheres as room dictates. Fortunately, I am not alone in this. Despite the recognition that the idea has been hijacked by everyone from management trainers to advertising copywriters, a number of the most knowledgeable people in the field have been unable to escape the conclusion that there is something profound here that requires explanation. Joseph Hellige, for example, arguably the world’s best informed authority on the subject, writes that while both hemispheres seem to be involved in one way or another in almost everything we do, there are some ‘very striking’ differences in the information-processing abilities and propensities of the hemispheres. V. S. Ramachandran, another highly regarded neuroscientist, accepts that the issue of hemisphere difference has been traduced, but concludes: ‘The existence of such a pop culture shouldn’t cloud the main issue – the notion that the two hemispheres may indeed be specialised for different functions.’  And recently Tim Crow, one of the subtlest and most sceptical of neuroscientists researching into mind and brain, who has often remarked on the association between the development of language, functional brain asymmetry and psychosis, has gone so far as to write that ‘except in the light of lateralisation, nothing in human psychology/psychiatry makes any sense.’ There is little doubt that the issues of brain asymmetry and hemisphere specialisation are significant. The question is only – of what?

I believe there is, literally, a world of difference between the hemispheres. Understanding quite what that is has involved a journey through many apparently unrelated areas: not just neurology and psychology, but philosophy, literature and the arts, and even, to some extent, archaeology and anthropology, and I hope the specialists in these areas will forgive my trespasses. Every realm of academic endeavour is now subject to an explosion of information that renders those few who can still truly call themselves experts, experts on less and less. Partly for this very reason it nonetheless seems to me worthwhile to try to make links outside and across the boundaries of the disciplines, even though the price may be that one is always at best an interested outsider, at worst an interloper condemned to make mistakes that will be obvious to those who really know. Knowledge moves on, and even at any one time is far from certain. My hope is only that what I have to say may resonate with the ideas of others and possibly act as a stimulus to further reflection by those better qualified than myself.

I have come to believe that the cerebral hemispheres differ in ways that have meaning. There is a plethora of well-substantiated findings that indicate that there are consistent differences – neuropsychological, anatomical, physiological and chemical, amongst others – between the hemispheres. But when I talk of ‘meaning’, it is not just that I believe there to be a coherent pattern to these differences. That is a necessary first step. I would go further, however, and suggest that such a coherent pattern of differences helps to explain aspects of human experience, and therefore means something in terms of our lives, and even helps explain the trajectory of our common lives in the Western world.

My thesis is that for us as human beings there are two fundamentally opposed realities, two different modes of experience; that each is of ultimate importance in bringing about the recognisably human world; and that their difference is rooted in the bi-hemispheric structure of the brain. It follows that the hemispheres need to co-operate, but I believe they are in fact involved in a sort of power struggle, and that this explains many aspects of contemporary Western culture.
[Introduction, pp1-3]

Essential Asymmetry
‘The universe is built on a plan, the profound symmetry of which is somehow present in the inner structure of our intellect.’ This remark of the French poet Paul Valéry is at one and the same time a brilliant insight into the nature of reality, and about as wrong as it is possible to be.

In fact the universe has no ‘profound symmetry’ – rather, a profound asymmetry. More than a century ago Louis Pasteur wrote: ‘Life as manifested to us is a function of the asymmetry of the universe . . . I can even imagine that all living species are primordially, in their structure, in their external forms, functions of cosmic asymmetry.’ Since then physicists have deduced that asymmetry must have been a condition of the origin of the universe: it was the discrepancy between the amounts of matter and antimatter that enabled the material universe to come into existence at all, and for there to be something rather than nothing. Such unidirectional processes as time and entropy are perhaps examples of that fundamental asymmetry in the world we inhabit. And, whatever Valéry may have thought, the inner structure of our intellect is without doubt asymmetrical in a sense that has enormous significance for us.

As I have said, I believe that there are two fundamentally opposed realities rooted in the bi-hemispheric structure of the brain. But the relationship between them is no more symmetrical than that of the chambers of the heart – in fact, less so; more like that of the artist to the critic, or a king to his counsellor.

There is a story in Nietzsche that goes something like this. There was once a wise spiritual master, who was the ruler of a small but prosperous domain, and who was known for his selfless devotion to his people. As his people flourished and grew in number, the bounds of this small domain spread; and with it the need to trust implicitly the emissaries he sent to ensure the safety of its ever more distant parts. It was not just that it was impossible for him personally to order all that needed to be dealt with: as he wisely saw, he needed to keep his distance from, and remain ignorant of, such concerns. And so he nurtured and trained carefully his emissaries, in order that they could be trusted. Eventually, however, his cleverest and most ambitious vizier, the one he most trusted to do his work, began to see himself as the master, and used his position to advance his own wealth and influence. He saw his master’s temperance and forbearance as weakness, not wisdom, and on his missions on the master’s behalf, adopted his mantle as his own – the emissary became contemptuous of his master. And so it came about that the master was usurped, the people were duped, the domain became a tyranny; and eventually it collapsed in ruins.

The meaning of this story is as old as humanity, and resonates far from the sphere of political history. I believe, in fact, that it helps us understand something taking place inside ourselves, inside our very brains, and played out in the cultural history of the West, particularly over the last 500 years or so. I hold that, like the Master and his emissary in the story, though the cerebral hemispheres should co-operate, they have for some time been in a state of conflict. The subsequent battles between them are recorded in the history of philosophy, and played out in the seismic shifts that characterise the history of Western culture. At present the domain – our civilisation – finds itself in the hands of the vizier, who, however gifted, is effectively an ambitious regional bureaucrat with his own interests at heart. Meanwhile the Master, the one whose wisdom gave the people peace and security, is led away in chains. The Master is betrayed by his emissary. 
[Into., pp13-14]

The above was extracted from The Master & his Emissary -The Divided Brain & the Making of the Western World.  Nominating it as Observer Book of the Year,  Salley Vickers called it "
a monumental account of right and left brain hemispheres...both brilliant & disturbing."  

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