How many times have you been told, “Oh you’re such a left-brain person,” meaning you think logically, are good with numbers, very analytical, and so on? And upon hearing that summation, you long for the right brain’s creative, intuitive, artistic complements. Why can’t they be part of the equation, you wonder.

We used to believe the two parts of the brain work in harmony, but according to London psychiatrist Iain McGilchrist, there’s a definite shift in our modern culture which favors left-brain dominance — and it’s something we ought to watch out for and correct. In “The Master and His Emissary: The Divided Brain and the Making of the Western World,” McGilchrist discusses the hemispheres and their different “personalities,” and then shows a sweeping dissertation on the history of Western civilization as seen from the context of the divided brain.

McGilchrist came to medicine later in life, following a distinguished career in academia. He is interested in a variety of psychiatric conditions, as well as neuropsychiatry. He also has a busy practice as a medico-legal expert and writes for numerous publications.

He named “The Master and His Emissary” after a parable that Friedrich Nietzsche told about a wise spiritual master who ruled a small but prosperous domain, who grew the land and appointed emissaries, one of which began to see himself as the master and used his position to advance his own wealth and influence. The emissary saw his master’s self-control and restraint as weakness, and usurped his master, creating a tyranny, and bringing the land to ruin.

McGilchrist likens the right and left hemispheres of the human brain to the master and the emissary of this story, respectively. McGilchrist weaves this cautionary tale to show that while the cerebral hemispheres should cooperate with one another, they have been in conflict for some time, with our current civilization in the hands of the emissary who, although gifted in many ways, functions as “an ambitious regional bureaucrat with his own interests at heart.”

Brain World: Can you describe the process of how the different brain hemispheres interact?

Iain McGilchrist: The theory that two hemispheres have differences comes from a simple Darwinian point: In order to survive, we need to be able to do two things at once. We need to be able to be busily focused on something that we’ve prioritized, like the bird needing to focus on picking up a twig to build a nest. At the same time, if it’s going to survive, the bird also needs a wide-open attention, looking out essentially for predators, not just in a threatening way, but also for its fellow creatures; indeed, for its mate.

Those two ways have somehow to be combined. And yet, if you look very narrowly at something and bring it into sharp focus in the middle of your vision, it’s very different from the contextual penumbra of other experiences — intuitively based, body-based, ancient, and gathered from a synthesis of all your experience, which you also bring to bear on the whole picture. Both have to be there, too.

That’s why I think the two hemispheres have evolved in this way. They need, to some extent, to be kept apart, because you can’t really do both things at once. The two hemispheres are connected by a bridge of tissue called the corpus callosum, which is commonly thought of as the thing that communicates between the hemispheres. It does. Although a lot of the communication is activating in its original sense — the nerves are stimulating something to happen — what they’re often stimulating to happen is in fact an inhibition. So their ultimate aim in a majority of cases is not to make something happen in the other hemisphere, but to stop something from happening there. And by filtering like this, things come into existence.

BW: You believe the left brain has been gaining control over the course of human evolution. How did this come about?

IM: I think an aspect of being a conscious being is that you are aware that you can become powerful by manipulation. Other creatures, of course, are competing and manipulating, but they’re probably not aware of the fact that this is a way of becoming powerful — that it seems to work well for a lot of the things that one does as one grows a civilization.

One needs to build structures by putting brick upon brick, or stone on stone. One needs to create drainage and irrigation and so on. One creates these things that seem to make life simpler, easier, and better and make you more powerful. It’s enticing, and you can soon begin to think that everything works like this. Everything in your world seems to break down into a lot of machines that we’ve created. While this is a very interesting way of looking at things, it’s basically a practical tool for getting ahead. It’s not really a very good instrument for epistemology or for ontology — for finding out actually what the world is and how we know about it. It can lead us to narrow down the way we think about things to a merely rationalistic set of propositions, a series of algorithms.

BW: What are the effects of the left brain taking over?

IM: One of the interesting elements that comes out in research into the “personalities” or the “takes” of the two hemispheres is that the left hemisphere thinks it knows it all, and as a result is extremely optimistic. It overvalues its own ability. It takes us away from the presence of things in all their rich complexity to a useful representation — that representation is always much simpler. And an awful lot is lost in it.

That’s not necessarily a bad thing. Sometimes you need to simplify. For example, if you’re designing a building, or if you’re fighting a campaign, you need a map, a scheme. You don’t really need all the richness of what would be there in the real world. But I’m afraid that that representation moves into a world where we have the ability constantly to interact with the world only as a representation, over a screen.

Even Facebook and social networking may look like you suddenly have loads of friends, but what it may actually do is take you away from your real-life friends so that your life is more crowded and there’s less time, actually, to be aware peacefully of the world around you and to interact socially — a word that used to mean “with your fellow creatures.”

BW: What can we do about this?

IM: People often ask me this question. I think they’re rather hoping I’ll give them a list of bullet points — “The 12 Things You Need” — like a best-selling paperback. That is really a perfect example of the left hemisphere. “Okay. Fix it by having a little plan. We do this, we do that, and bingo!” But in fact, what I have tried to convey throughout the entire book is that the world, as it is, has its own shape, value, meaning and so on, and that we crowd it out with our own plans, thoughts and beliefs, which are going to be narrow.

A wise thing to do would be not to do certain things. Another theme of my book is that negation is creative. That by having less of something, more comes into being. So actually what we need to do is not create a world. We need to stop doing lots of things and allow the wonderful thing that is already there to evolve, to give it room to grow. That’s also true of a single human mind.