The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts —Bertrand Russell

Preamble In 2009, Iain McGilchrist published The Master and his Emissary in which he proposed a paradigm-altering thesis on the nature of the bi-hemispheric human brain. Among his many novel insights, two stand out: first, that each hemisphere invites a quite different style of attention to the world; and second, that the style of attention we pay transforms the world we perceive.

This latter insight bears repeating: the style of attention we pay transforms the world we perceive.

The following text is from an unpublished essay by McGilchrist which will appear in full in an upcoming book titled Speak to the Wild. Reading it invites us to consider the possibility that the profoundly different approaches to life that differentiate, say, a Donald Trump from a Mother Teresa may trace to very different world views brought to bear by the left and right hemispheres respectively. Ditto antivaxxer, whose behaviour relative to the public good suggests a world view very different from that of just about everyone else: this too aligns well with a bi-hemispheric reading.

If McGilchrist’s framing is valid – and many cognitive neurologists now subscribe to it – then the crucial point to take from it is that the very act of experiencing the world from a left-hemispheric perspective brings into focus a world qualitatively very different from the world experienced through the right hemisphere.

Extrapolating, this suggests that inordinately self-interested people should not be understood as “selfish” in the usual sense of that word, but rather as acting in accord with the world as it manifests to them – a subtle distinction maybe, yet one with crucial implications, or so it seems to me, for humanity’s ongoing inability to mount a commensurate response to the Climate Crisis. For while agreement is never far off between people who debate across the self-same playing field, yet the situation is far otherwise between people who debate from different worlds – an inference I formalize elsewhere in this website.



hat the brain is deeply divided into two hemispheres is a fact so fundamental that it has been taken for granted, and yet so extraordinary that it cries out for explanation. For the brain is an organ the whole purpose of which is to make connections. When one realises that the main function of the bundle of tracts by which the hemispheres are joined, the corpus callosum, is to inhibit, the puzzle is compounded.

human brain

In [my book], I suggest that evolution has carefully preserved the division of the brain into two hemispheres. I argue that, like our bird and animal relatives, we need to be able to apply two different types of attention to the world: a narrowly focussed, precisely targeted attention to what we have already decided is of importance to us, and at the same time the broadest possible attention to whatever is ‘out there,’ without preconception.

These two types of attention are so distinct in their nature that they cannot take place in the same ‘brain’ at the same time – hence the division. Having a bi-hemispheric brain enables birds and animals to pick out a seed or lock onto the prey they are chasing, while at the same time being vigilant for whatever is going on around them, in particular for predators of their own. So it is essential for their survival.

I believe that understanding the significance of this hemispheric divide is essential for our survival too, for reasons I shall explain – and which will carry us far beyond the simplistic ideas about logic and language being attributes of the left hemisphere and emotions of the right.

Already in animals and birds one gets an idea of the uses of lateralisation. Their ‘speech’ comes from the left hemisphere; and if they use tools they tend to do so with their left hemisphere. With their right hemisphere, meanwhile, they recognise and relate to their kind, form bonds, discriminate individuals, and use global or Gestalt strategies for identification, rather than categorising by the presence or absence of certain features, which is how the left hemisphere sees difference. All these differences are in keeping with those found in the human brain.

This gives a new impetus to hemisphere difference, because for the purpose of exploitation and use we need to see something different from what we see when we feel ourselves in connection with the world. With one hemisphere, the left, we create a sort of simplified but useful map of the world that makes us efficient at using it. At the same time, with the right hemisphere, we need to be aware of the world outside ourselves, so as to be open to new understanding.

The world of the left hemisphere is dependent on denotative language and abstraction, and so yields clarity and power to manipulate things that are known, fixed, static, isolated, decontextualized, explicit, disembodied, general in nature, but ultimately lifeless. The right hemisphere, by contrast, yields a world of individual, changing, evolving, interconnected, implicit, incarnate, living beings within the context of the living world, but in the nature of things never fully graspable, always imperfectly known – and to this it exists in a relationship of care.

The knowledge that is mediated by the left hemisphere is knowledge within a closed system. It has the advantage of perfection, but such perfection is bought ultimately at the price of emptiness, of self-reference. It can mediate knowledge only in terms of a mechanical rearrangement of other things already known. It can never really ‘break out’ to know anything new, because its knowledge is of its own re-presentations only. Whereas the thing itself is ‘present’ to the right hemisphere, it is only ‘re-presented’ by the left hemisphere, now become an idea of a thing. Where the right hemisphere is conscious of the Other, whatever it may be, the left hemisphere’s consciousness is of itself.

Beyond this, one could say that the right-hemisphere way of attending to the world is whole-perceiving, organically-minded, expectant of newness and interested in whatever lies outside itself; while the left-hemisphere way is narrowly focused, mechanistically-minded, certain of what it already knows and interested in its own purposes. In the right hemisphere world there is what I call ‘betweenness,’ not just the sense of connectedness with the world, but the sense that things come into being ‘between’ ourselves and whatever else there may be – a sense that is lacking in the left hemisphere world, where there is a separation of subject and object. Finally, the right hemisphere is uncertain, where the left hemisphere is full of a delusive certainty, and is in a state of optimistic denial.

Cognition is, I believe, a three-part process in which what begins in the right hemisphere’s world is ‘sent’ to the left hemisphere’s world for processing, but must then be ‘returned’ to the world of the right hemisphere where a new synthesis can be made. It is worth emphasizing that the right hemisphere needs not to know what the left hemisphere knows, for that would destroy its ability to understand the whole. [On the other hand, the left hemisphere’s strength lies in its ability to] render explicit what the right hemisphere must leave implicit. But that is also its weakness, for in the act of clarifying the implicit, the left hemisphere renders it abstract, lifeless. If the perspective given by the left hemisphere is to live again, it must be handed back to the domain of the right hemisphere, where it is contextualized, reintegrated with the sense of the whole.

Perhaps an analogy would be the relationship between living and reading. Life can certainly have meaning without books, but books cannot have meaning without life. In one sense a book, like the world according to the left hemisphere, is a selective, organized re-presented, static, revisitable, boundaried, ‘frozen’ extract of life. It has taken something infinitely complex, endlessly interrelated, fluent, evolving, uncertain, never to be repeated, embodied and fleeting (because alive) and produced something in a way very different that we can use to understand it.

Though obviously far less complex than life itself, it has nonetheless brought into being an aspect of life that was not there before. So the left hemisphere (like the book) can be seen as taking from the world as delivered by the right hemisphere (unconsidered life), and giving life back enhanced. But on the shelf, the contents of the book are dead: they come back to life only in the process of being read. No longer static, boundaried, ‘frozen’, the contents of the book are taken up again into the world (of the right hemisphere) where nothing is ever fixed or fully known, but always becoming something else.

Next up: Path Less Traveled By