SPLIT BRAIN, SPLIT VIEWS – DEBATING IAIN MCGILCHRIST
February 24, 2013 § 22 Comments
Iain McGilchrist has written a response to my post about his book The Master and his Emissary and about the RSA workshop that discussed it. Since it is a long reply, Iain asked me whether I could publish it as a post, rather than as a comment, which I am happy to do. I have appended my own response at the end. (And just to avoid any confusion, while I have set up the discussion in the form of two open letters, Iain’s piece was written as a straightforward essay, not in letter form.) I am slightly puzzled, as I observe in my reply, by the tone of Iain’s piece. He seems to suggest in places that my original was written in bad faith and that I seem not to have not read his book or the RSA document. Whether I have adequately understood either is, of course, a matter for debate. But my post was written in good faith, and while critical of Iain’s thesis was also, in my eyes at least, respectful of his work. I wrote it to engage in the kind of debate for which I had hoped that Iain himself had written his book, and the RSA had held its workshop. I am publishing Iain’s essay in the spirit of such debate, I have written my response to it in that spirit, and I hope that people will engage in that spirit with both sets of arguments.
When Jonathan [Rowson, Director of the RSA’s Social Brain Centre] and I agreed to attempt this short publication we did so with a degree of foreboding. We knew that the attempt to abbreviate an argument that is, for the most part, carefully articulated, and already somewhat compressed, in its original 350,000 word form, was inviting difficulties. One such difficulty was that in further compression much would be lost: subtlety, nuance, complexity of argument, qualification of expression, and that I would be taken as saying something cruder than I am. Another was that the casual reader might be lead to think that they could substitute an acquaintance with the paper for a careful reading of the book. Yet we were encouraged by the advice of many readers from many academic disciplines and from many walks of life to think that it was worth risking such casualties in order to engage readers who otherwise might not have come across it at all, trusting that, at least before passing judgment, they would be led to do the book justice by reading it for themselves.
But perhaps even the RSA document is too long for today’s reader. Our fears would appear to have been more than justified. It is a little dispiriting that most, if not all, the comments and objections that KM raises are addressed, sometimes at considerable length, in the course of the document. Of course, those responses might still not satisfy KM, but at least if he had read them the debate would be at a higher level.
I am sure that, as a scientist, KM would agree that science involves acquainting oneself with the facts, keeping an open mind, and trying to maintain balance in considering the whole picture.
On that last matter, it is interesting, and not a little sad, that KM refers to the contribution of only one participant at the RSA workshop, probably the only one out of the 20 or so present who appeared largely unconvinced, Ray Tallis. Dissenters to any proposition are to be expected. And indeed Ray and I are nowhere near as far apart as this might suggest: our standpoints on all the big issues involved here are almost identical, and it is in fact only by attributing beliefs to me that I do not hold that he could find targets to criticise. You would not think from KM’s account that I had in fact responded, as did several others, to every one of the points that Ray is quoted as making. Similarly the only review KM refers to, that of Owen Flanagan, is also the only truly negative review the book has received out of about 50 or so published reviews or commentaries, most of which have been to say the least, positive. It is also the weakest review – of course I would say that, wouldn’t I? But anyone who has read my book and reads that review will realise what a shameful piece of writing it is. The review appeared the same week that the book came out, and so one could hardly expect the author to have read it (most thoughtful readers say that it takes about two or three months to get properly to grips with). But ignorance doesn’t make a promising basis for an informative review. You can see how well Flanagan understood his subject by the fact that he does not seriously engage with anything in it – not the science, the philosophy, the cultural history or anything else, manages to misunderstand the primary metaphor of the book by getting the Master and the Emissary the wrong way round (you only have to get to p 14 to get that right), accuses me of wanting us all to ‘sit on the beach and sing Kumbaya’, and thinks I want to reduce human history to brain events. A cursory read would have saved him such howlers. The entire drift of the book is against such reduction of human phenomena to brain events. It would not be the first time that shoddy invective made up for lack of care and ignorance of one’s subject, but one might have expected better of a journal with Science in the title. In fact Professors Alwyn Lishman and Mary Midgley wrote to take issue with such a travesty, but the New Scientist, which clearly does not like to be exposed, was apparently not able to find space for such distinguished writers to attempt objectivity.
On the hypothesis of The Master and his Emissary, balance in treating this tertiary evidence – what people generally say about the book and its hypothesis – would have been one way KM could have displayed an open mind. Another would have been balance in treating the secondary evidence – reading the book and being fair to its arguments. I get no sense that KM has read my book, but if he has, he would appear not to have understood it. I am very definitely not a critic of reason. Quite the opposite. I am a critic of what has in our time come to take the place of reason, a mindless rationality which neglects judgment and experience. In most languages other than English, certainly in German, Greek and Latin, there are different words for these kinds of reason (eg Vernunft versus Verstand, nous versus logos/dianoia, intellectus versus ratio). As Mary Midgley pointed out in her Guardian review, it is not about thinking versus feeling, but about two kinds of thinking. The difference is similar to that made by Aristotle between phronesis and techne: I have never heard Aristotle accused of being a New Ager. Just because I believe that certain questions do not have answers that could ever be proved to be true does not mean that I think anything goes, and that we are condemned to the realm of the purely subjective. Absolutely not. I could not have made this point clearer in my writings. On all these matters I am KM’s ally. I am also a defender of the proper use of language in an age where both reason and language are too often travestied. But, in turn, it would be sloppy thinking to assume that that meant that there were no limits to what language can precisely express.
Analysis itself shows the limits of analysis, reason shows the limits to reason. As Pascal said, ‘the ultimate achievement of reason is to recognize that there are an infinity of things which surpass it. It is indeed feeble if it can’t get as far as understanding that.’ This famous mathematician also wrote: ‘Plenty of things that are certain are mutually contradictory; plenty of things that are false contain no inconsistency. Contradiction is not a sign of falsehood, nor the lack of contradiction a sign of truth.’ He also wrote: ‘it is equally excessive to shut reason out and to let nothing else in’. The mistake that some readers make is to think that I see no place for reason if I argue the case for carefully nurtured intuition (people who reason well have better intuitions, people who have good intuitions reason better) in a world that has ceased to respect it. We need both. One hemisphere difference KM would read about in my book is that this black and white, either/or, ‘if it isn’t this, it must be that’ attitude is characteristic of the left hemisphere’s exclusive, precision-directed outlook, when compared with the ability of the relatively inclusive right hemisphere to see more than one option and to hold them together.
But what about balance in treating the primary evidence – the scientific data? I don’t know how well KM knows the literature on hemisphere asymmetry. I say that merely because there are not many people these days who really know it well, partly because of the very prejudice which has led scientists to neglect the issue for the last approximately 30 years. He does say with an air of authority that I have ‘cherry-picked data’, so maybe he is well-versed in it (although I suspect he may have borrowed this idea from the insightful Flanagan). In my case, it took 20 years to familiarise myself with this literature, in so far as I can say I have. I did not speak about hemisphere asymmetry, nor write about it except in the context of a few technical papers reporting research data, until I had spent two decades pondering the material and being fairly sure I was not misrepresenting it. (Incidentally, it would be quite counterproductive for me to attempt misrepresentation, since my only interest is in finding out what is actually the case. That is all that has kept me going: not having a large budget or the likelihood of a prestigious chair to pursue, there have been no temptations in my path.) It is a rather too simple dismissive comment to say ‘he’s cherry-picked the data’. In reality most people can’t have that kind of knowledge of the area. I quote from about 2,500 papers, and I am not sure how many more would have satisfied. I didn’t pin my argument on a handful of unrepresentative findings. It’s also somewhat underhand, if I may say so, to talk of cherry-picking, because it involves the critic in no work, can’t be answered except by silence or indignation, depending on one’s mood, and casts aspersions which cannot easily be dispelled, while giving the impression that the critic is far more knowledgeable than his critical object. Quite a reward for little effort! Unless the critic is willing to demonstrate a knowledge of the asymmetry literature and show me what he is talking about in the context of the whole, it is not a remark that should be made. And, by the way, a study or even a brace of studies, that do not chime will not in themselves do. Nothing in the biological sciences yields entirely consonant data. One must see the whole. A finding can be perfectly valid, and even of the greatest significance overall, and yet admit of contrary findings. The average temperatures in Iceland and Indonesia are clearly very different, which goes a long way to explain the wholly different characteristics of the vegetation, animal life, landscape, culture and economy of these two regions, as well as no doubt much else that differentiates their ‘feel’ and the ways of life there. But it is still true that the lowest average annual temperature in Indonesia is lower than the highest average annual temperature in Iceland – and of course the average temperature varies considerably from month to month, as well as, less predictably, from day to day, and indeed from place to place within each region. The nature of generalisations is that they are approximate, but they are nonetheless of critical importance for understanding what is going on. A misplaced need for certainty may stop the process altogether. I know that that means that the critic would have to address the whole of the data, not just pick off bits, but that is the price of fairness and objectivity.
Having said all of that, it is not as though I do not refer to contrary data. Originally I did so in the body of the text, but my editor, I think wisely, suggested that all such excursus should be put in the notes, in order not to lose the thread of an often complex argument. So KM should read the footnotes too, I am afraid. I might add that many who do really know this literature – Colwyn Trevarthen and James Wright, both of whom researched split brains with Roger Sperry at Cal Tech, Jaak Panksepp, VS Ramachandran, Michael Trimble, Alwyn Lishman, Jurg Kesselring, Todd Feinberg and others – think I represent it well enough.
Let me just remind the reader that the brain is not only profoundly divided, but profoundly asymmetrical. There are clear, subtle but significant, observable differences at every level. The two hemispheres are different sizes, shapes, and weights (the right hemisphere is bigger and heavier in all social mammals); have different gyral conformations on the surface, and in places different cytoarchitecture – that is to say the arrangement of the cells; different proportions of grey matter to white, different sensitivity to neuroendocrine influences, and rely on different preponderances of neurotransmitters. And in psychometric testing they consistently yield different results, which is in keeping with something any clinician could tell you: when there is damage to one hemisphere or the other, through injury, tumour or stroke, there are consistent differences in what happens to the subject and his world depending on which hemisphere suffers the lesion.
So before we move on to look at specifics, let me ask KM some questions.
1) Given that the brain consists in a mass of connections, whose power depends on the number and complexity of those connections, why is it divided? Or is that just random, and we should give up trying to find a pattern which make sense in terms of evolutionary advantage? (Animal ethologists have already found that asymmetry is an evolutionary advantage, and some of the reasons why – I take those into account in the book.) 2) Is it logical or just a prejudice to dismiss the idea that there are significant hemisphere differences? 3) If it is logical, why? If it is not logical, should we not all be interested in what sort of difference this might be? 4) If not, why not? If so, what sort of difference would he himself suggest? 5) Failing any suggestion of his own, why is he opposed to others making suggestions? 6) Since it is in the nature of a general question that the answer will be general, what sort of criticism is it that an answer that has been offered is general in nature (though highly specific in its unfolding of the many aspects of cerebral function involved, of the implications for the phenomenological world, and in the data that are adduced)? 7) It is in the nature of generalisations that they are general. It is also almost always the case that there will be exceptions. Does that mean that no generalisations should ever be attempted for fear of being called generalisations or because there are exceptions? 8) I have never tried to hide the difficulties surrounding generalisations. My book is replete with caveats, qualifications, and admonitions to the reader. Does either KM or Ray Tallis think they have said anything substantial by calling a generalisation ‘sweeping’? What kind of generalisation is not, other than one that is qualified?
Turning to specifics, KM quotes Ray Tallis as follows.
McGilchrist’s thesis, a thesis that is ‘highly systematising, linguistic, explicit etc’ and is built upon ‘massive quantities of painstakingly acquired, precise data, 2,500 sources’, looks, Tallis suggests, ‘rather left hemisphere according to his own characterisation’. The left hemisphere, according to McGilchirst [sic], is ‘out of touch with reality’. ‘Doesn’t this make it rather odd’, Tallis asks, ‘that he relies on the neurological data presumably gathered by that hemisphere to support his extraordinarily ambitious account of ‘reality’, a reality that encompasses the history of mankind?
There are a number of points to make here.
First, I have no quarrel with using the left hemisphere. We all use the left hemisphere all the time! Civilizations, as I again constantly remind people, are founded on it. It is the same old basic mistake to suppose I am arguing against the usefulness of the left hemisphere. I myself rely on the world as revealed by the left hemisphere very substantially, as Tallis says. My quarrel is not with the left hemisphere per se. It is with a lack of balance between left and right. My suggestion is that the left hemisphere is not aware of its own limitations – this is a neurological as much as metaphorical truth. Sometimes people say, ‘you’ve depicted the world according to the left hemisphere – what would the right hemisphere world look like, then?’ To which I answer, ‘very balanced’. Because the right hemisphere is more aware that it needs the left hemisphere than the left hemisphere is aware that it needs the right. This idea is embodied in the parable of the master and his emissary.
Second, reliance on data and evidence is at least as much in keeping with the right hemisphere’s take on the world – with what is actually the case, rather than with what accepted opinion tells us is the case, which tends to be more typical of the left hemisphere’s stance.
Third, the left hemisphere is only out of touch with reality when it fails to work in partnership with the right. Tallis’s point is, once again, illogical, since I use strategies of the left hemisphere – yes – and of the right, to convey the complexities of the world as the right hemisphere is aware of it – a difficult thing to achieve because the language that is available naturally construes things in the left hemisphere sense, but necessary because it is no use expressing the right hemisphere’s perceptions only in right hemisphere ways – implicit, rather than explicit ways – if you want to reach people who are currently, for cultural reasons, over-reliant on the left hemisphere’s take on the world. If you, then, as I have done, make heroic efforts to speak to the left-hemisphere culture in terms it will understand, you are accused of using left hemisphere strategies … not an accusation I feel at all concerned about.
Fourth, I am not trying to give a comprehensive account of ‘reality’, or of the history of mankind – which would be an overambitious undertaking for a team of scholars working for centuries. I am trying to do something much more modest. I am pointing to differences in the ways our cerebral hemispheres attend to the world, to the differences this makes to the way we construe the world, and to how reconciling these conflicting, but nonetheless both necessary, ‘versions’ of the world might be expected to be reflected in the history of ideas. I deal with the history of the West, true, but only in that one respect – whether we see something new or thought-provoking emerge when we look at each of the great epochs of the history of ideas in the light of what we know about the cerebral hemispheres.
I have commented on the problem of what seem to be ‘sweeping’ generalisations. Personally, I love the unique and particular, and if KM were to read my book, he would find it contains many examples of both. But in a short document one can only speak shortly. To talk of the left hemisphere ‘using’ the world is shorthand, which makes more sense to those who have read why I reach that conclusion. It refers to a point argued at some length that the left hemisphere’s narrowly focussed attention has evolved in response to an evolutionary need, manipulation of the external environment (which is incidentally why the right hand, which it controls is the tool-utilising hand, and why its contributions to language are the parts which enable us to ‘grasp’ something (cognates of ‘grasp’ exist in almost all languages). There is a mass of (to me at least) fascinating data about this which fleshes out the picture: for example, the current mainstream hypothesis that speech evolved from bodily gestures, in particular hand gestures (located in the same part of the left frontal cortex near Broca’s area).
Equally the point about Far Easterners in comparison with Westerners is a shorthand for the exposition of a fair number of studies over the last 20 years that suggest that we differ not only in the ways in which we think, but even in what we perceive (which is what one would expect from the fact that there are attentional differences). This is dealt with at greater length in the book. In relation to this, it is not accurate to say that ‘McGilchrist has taken a long-standing dubious argument about cultural differences and modernized it by locating it in the brain’. First, the old cliché was that the West was ‘left-hemisphered’, and the East was ‘right-hemisphered’. What the data suggest is more interesting: that people in the Far East use strategies of both left and right hemisphere equally, whereas Western responses have become strongly skewed towards the left hemisphere point of view only. It’s not a point about some oddity of Easterners, but yet another sign, if such a sign be needed, that our culture has become less balanced in its outlook. Second, I report studies which show such differences in experimental situations. Does KM dispute the studies? Only if so, can I see the problem here. If he does, on what basis does he dispute them? Does he think they do not really demonstrate any difference?
One point KM makes is, however, quite legitimate. ‘But McGilchirst [sic] insists that the Master and Emissary, and the idea of the one usurping the other, are more than simply metaphors. What could this mean? … clearly McGilchrist is saying more than simply that we are over-relying on one hemisphere. He is suggesting that the way the two hemispheres operate has somehow allowed the emissary to usurp the Master, the left hemisphere to usurp the right, and to colonize our experience. And it has done so independently of our desires or needs or wishes. For only then would the neuroscience be relevant to the social issues that McGilchrist raises. But in what way is it operating independently? Presumably, McGilchrist is not suggesting that the hemispheres are agents in their own right. So what is he suggesting? He does not say.’
In fact I do, and many others have helped articulate it. I would draw KM’s attention especially to the response of John Wakefield, included in the RSA report, which KM would seem not to have read along with much else. The point is a difficult one to convey because we think – I would say ‘in left-hemisphere fashion’ – only in terms of linear causation. Either the brain must ‘cause’ events in the phenomenological world, or the phenomenological world ‘causes’ the brain to be the way it is. A constant theme of my book is the importance of the hermeneutic circle. Indeed it is a primary point of understanding for the whole hemisphere hypothesis that there is not a naively realist, objective world that exists apart from our knowing it, but also that there is not a naively idealist, subjective world, equally omnipotent and impotent, post-modern fashion. Brain and the world – each shapes the other, and various worlds with different characteristics come into being as a result of the nature of the attention we pay to whatever it is that exists apart from ourselves. There is a constant dialogue between brain and environment, which is traceable, if one wishes to do so, at the level of the synapse, but is also traceable at the phenomenological level. Each helps to mould the other. And so the answer to the left hemisphere question ‘which causes which?’ is – right hemisphere fashion, ‘both and neither’. But out of that relationship everything that we know, or can know, ultimately comes.
You can find JW’s subtle and rewarding piece on pp 71-76 of the RSA document.
I am sorry that you should seem so irritated by my post, and somewhat puzzled as to why you should be so. The original post was written in good faith and while it is critical of your argument, it is also, it seems to me, respectful of it and of your work. I had assumed that it was precisely this kind of debate that you wanted to generate with your book. Perhaps I was wrong.
A couple of minor points before I answer some of your questions. First, you suggest more than once that I have not read The Master and his Emissary. Given that I quote at length from the book (and you must know that all the quotes from you in the post were taken from The Master and his Emissary, apart from one which came from your website), it is difficult to see how I could not have read the book. It is striking that you seem to think that only those who agree with your argument have actually read the book properly. That is perhaps an understandable sentiment (I feel the same way sometimes about criticisms of my books). All I would say is that it is quite possible to have read the book thoroughly and still disagree with your argument.
Second, you suggest that ‘it is interesting, and not a little sad, that KM refers to the contribution of only one participant at the RSA workshop, probably the only one out of the 20 or so present who appeared largely unconvinced, Ray Tallis’. What I actually wrote was that
McGilchrist’s argument has won considerable support and praise, not least from the participants at the RSA workshop. The workshop opened, however, with a critical review of the argument from Ray Tallis.
I acknowledged, in other words, the support your thesis has won (elsewhere I mentioned ‘the praise showered upon The Master and his Emissary’) but sought deliberately to pick up on Tallis’ criticisms. Why? Because, first, it was the key response at the RSA workshop and in the RSA document itself; and, second, because it chimed with concerns I have with your argument. I was writing a blog post, not a comprehensive review of all the responses to the book or the thesis.
So, what of that thesis? You ask a series of eight questions. In order to keep this response to a moderate length, let me collapse those eight into two key sets of questions:
Is it logical or just a prejudice to dismiss the idea that there are significant hemisphere differences? If it is logical, why? If it is not logical, should we not all be interested in what sort of difference this might be?
I am not sure where I might have suggested that there are no significant differences between the hemispheres, or that we should not be interested in such differences. All I did was to query the kinds of labels you hung on the two hemispheres – for instance that one is ‘narcissistic’ and ‘driven forward by a desire for power and control’, while the other possesses ‘ideals’ consonant with an outlook that is ‘essentially local, agrarian, communitarian, organic’. These, it seems to me, are labels that belong to the whole person in a social context, not things that one can attribute to an isolated hemisphere.
It is in the nature of generalisations that they are general. It is also almost always the case that there will be exceptions. Does that mean that no generalisations should ever be attempted for fear of being called generalisations or because there are exceptions? Does either KM or Ray Tallis think they have said anything substantial by calling a generalisation ‘sweeping’? What kind of generalisation is not, other than one that is qualified?
We all make generalisations. But it is nature of the generalisations in your book that I was questioning. When someone suggests that the distinction between the ideas animating the French and American Revolutions can be understood in terms of hemispheric differences, then I get queasy. Similarly when you suggest that early Jeffersonian democracy was ‘in harmony with the ideals of the right hemisphere’ but that later democracy ‘came to be swept away by the large-scale, rootless mechanical forces of capitalism, a left-hemisphere product of the Enlightenment’. The ideological differences between the French and American Revolutions, or the changing character of democracy, are immensely complex issues; to reduce them to the left hemisphere-right hemisphere distinction seems to me to be, to say the least, unwarranted and unhelpful.
I have no doubt, even though my first degree was in neurobiology, that you have a vastly superior knowledge of brain lateralization. That does not mean, however, that I cannot criticize either your use of data or, more pertinently, your interpretations of that data, and the generalisations you draw from them. I am sorry if my line about ‘cherry-picking and idiosyncrasy in the presentation of [the] data’ upset you. I was not trying to question your knowledge or impugn your integrity. I was simply pointing out that the kinds of unwarranted generalisations to which I have just alluded requires one to be highly selective and idiosyncratic in one’s interpretation of the data.
In any case, my key criticism was not about the data on lateralization. It was, rather, about the link you make between the neuroscience, on the one hand, and, on the other, the social and philosophical problems you raise, and your insistence that the first is an explanation of the second.
You seem to think that you (and John Wakefield) have answered this criticism. And not for the first time you insist that I disagree with you only because I ‘seem not to have read [the RSA report] along with much else’. Let me say again: It is quite possible to have read your book and the report thoroughly and still disagree with you. Since you flag up John Wakefield’s comments as addressing my points, let me say a few words about those comments. According to JW
[McGilchrist] insists that his book provides no ‘causal explanation’ of what may be going on in the world. He says that when asked what the book tells us about the world that could not be discovered by other forms of human inquiry his answer is: ‘Nothing’.
If this was the case then we would, indeed, have nothing to debate. But this is not how I understand your argument. As you put it your book, ‘I believe [the hemispheres] are in fact involved in a sort of power struggle, and that this explains many aspects of contemporary Western culture’ [p3]. If the ‘power struggle’ between the hemispheres ‘explains many aspects of contemporary Western culture’, then clearly you are providing a ‘causal explanation’ and suggesting, if not insisting, that ‘what the book tells us about the world… could not be discovered by other forms of human inquiry’.
What exasperates Iain is that Ray [Tallis] is saying nothing (Iain claims) that he has not himself said in the book.
Your critique of Tallis (and of me) is, in fact, more than simply that we repeat what you have already said. It is that we are mistaken in many of our claims.
JW also suggests:
[McGilchrist] is telling us that in inhabiting the world we inhabit we are increasingly in thrall to the left hemisphere’s ‘take’ and that this is radically affecting our behaviour and, as a consequence, the very substance of the actual world we are living in.
If this means that we are increasingly in thrall to a decontextualized, mechanistic culture, or that we are over-relying on one hemisphere, then, as I wrote in the post, I partly agree. But, as I suggested above, you seem to mean much more. You seem to want to provide a causal explanation, to insist that the left hemisphere’s ‘power struggle’ with the right, the emissary’s usurpation of the Master’s role, is somehow driving the social and intellectual changes. That is where I disagree.
Finally, JW suggests:
Iain’s thesis provides us with ‘an understanding’ that is metaphoric and that may (or may not) one day come to be regarded as literal.
Insofar as the thesis is metaphoric, I do not have a quarrel with it as such (though I would question both the over-generalisations and some aspects of the presentation of the intellectual history). But I was, in my post, pointing out some of the conceptual problems in thinking about your thesis as providing a ‘literal’ account. For instance, you write in your post, in response to Ray Tallis’ criticisms:
My suggestion is that the left hemisphere is not aware of its own limitations – this is a neurological as much as metaphorical truth.
What does it mean to say that the ‘left hemisphere is not aware of its own limitations’? It is, after all, not an agent in its own right. It is not aware of anything. It is only the person who is aware.
I am not, of course, suggesting that the structure of the brain has no impact on the character of our perception or understanding. Clearly it does. What I am suggesting is that part of the conceptual problem in your argument is the constant elision between brain (or hemisphere) and person, an elision that allows you to attribute agency to a hemisphere while denying that you are doing so. If what you mean by the sentence above is that ‘the person embodying the left hemisphere is not aware of that hemisphere’s limitations’ in the sense that he or she is unaware of the limitations of ‘left hemisphere kind of thinking’, then I would agree with you, but it would seem to be a truism. But if what you mean is that the left hemisphere ‘is unaware of its own limitations’ as an agent in its own right, independently of the person embodying it, then it becomes far more than a truism. But it also becomes a highly implausible account of agency, consciousness and personhood. Your thesis, it seems to me, rests to a large degree upon this ambiguity in the understanding of agency.