Back in November, I read The Master and His Emissary: The Divided Brain and the Making of the Western World, Iain McGilchrist’s much-lauded and very influential work from 2009. I liked the first half of it very well, and disliked the second half in equal degree.

The first part of the book is an excellent introduction to research on how the left and right hemispheres relate. The picture McGilchrist presents is quite different from the older pictures of this lateralization of the brain: subtler and more interesting than the old canards about “left-brained” and “right-brained” people and subjects and fields. In particular, McGilchrist describes the importance of the integration of the left and right hemispheres. He offers fascinating experimental evidence from neuroscience and psychology on patients with split brains (i.e. where the corpus callosum has been severed) or lesions that effectively disable one or the other hemispheres. The two hemispheres are very obviously very different: the right more integrative, the left working more piecemeal. Either alone ends up with significant gaps — literal sensory gaps, because of how the parts of our body are wired up to the brain, but also cognitive gaps because of the way they have specialized functions. The left hemisphere’s verbal comprehension needs the right hemisphere’s integrative sense-making, but the right hemisphere’s ability to work with metaphor and reasoning is “mute” without the left — and so on.

From these observations McGilchrist draws some interesting insights about what happens when the hemispheres are “out of balance” in some way. He focuses in particular on how left hemisphere dominance can end up with a particular kind of blindness toward broader context and a severe lack of awareness of its own limitations. So far so good, and given the nature of most of the studies he cites, most of this stills stands up in the wake of the replication crisis, very much unlike, say, the results cited to such striking effect in Thinking, Fast and Slow.

Alas, the second half of the book is much less careful, much less rigorous, and much less interesting. From those fascinating observations about biology and psychology, McGilchrist pivots to of cultural analysis. He argues at great length that the entire history of Western thought from the emergence of Greek philosophers forward is the history of the ebb and flow of left hemisphere dominance over the right, with the left slowly but surely pushing beyond healthy balance eith the right and to a position of ascendance. Periods McGilchrist likes he frames as evincing a healthy balance between the hemispheres; periods he dislikes he frames as representing left hemisphere dominance.

He explains too much: he explains everything. This ends up being a kind of reductionism. Everything fit into a neat little schema. Everything is explained by the different, competing “wills” of the two hemispheres. Ironically, this kind of schematization is just where he accuses an overly-dominant left hemisphere of going wrong!

I could go on at great length about how the second half of the book falls far short of the first half in clarity, coherence, and for that matter simply accuracy. I will content myself instead with two comments, which stand in well for whatever further elaboration I could offer.

First, in areas of history I know reasonably well, McGilchrist’s claims were often ludicrously wrong. His characterization of the nature of the Protestant Reformation was the kind of cliched stereotype I might expect from the worst kind of Roman Catholic apologetics,¹ and bears little resemblance to the historical realities; it gives precious little shrift to the Reformers’ actual stated arguments; it frames the Reformers actions in the most hostile of lights.

Being aware as I am of the Gell-Mann amnesia effect, this also led me to significantly discount his other historical claims, even where they were not quite so obviously being selectively edited to make his point.

Second, the claims in the second half of the book simply do not admit of falsification. To the contrary, McGilchrist adopts a classically specious form of argument in which any argument against his view can simply be dismissed as left hemisphere thinking which cannot integrate his more holistic and metaphorically-rich right hemisphere frame.

In practice, this comes out as a series of motte-and-bailey moves. He advances the idea of the left hemisphere steadily encroaching on the territory of the right, of its constructing a whole world shaped so that it does not have to encounter things outside its comfort zone. On any rejoinder, though, he can fall back to claiming (as he does at several points) that the idea of the left hemisphere as having a will is just metaphorical language. Well: which is it? If you want to claim that the left hemisphere is doing something, it cannot be purely a metaphor. To this he replies (of course!) that this is “left hemisphere”, black-and-white, polarized thinking, rather than the holistic, integrative thinking favored by the right hemisphere. Again: no argument allowed.

In sum, you could read and profit well from the first half of the book; but the second half is simply not worth your time. There might be some interesting things to be said of an imbalance between left and right hemispheres in our world, and a few of them even appear in The Master and His Emissary. Unfortunately, they are hard to find amidst the rest of the work, and your time would be better spent elsewhere.

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Notes

1. To be clear, I make no commentary here on good Roman Catholic apologetics — with which I still differ significantly, but which are aware of and are indeed much chastened by the strongest arguments of the Reformers, even while they still have significant differences! ↩︎