The question of dichotomising has been raised again by a reader, and since it is so often raised, and since it is so important to be clear about it, I am going to devote a post to it, and then hope to move on.  Unless someone comes up with something so earth-shatteringly important on the topic that I cannot ignore it, I will try not to keep revisiting it, but in future just refer back to this post. 

There are different types of dichotomising.  Except as a sort of exasperated, comic shorthand, it is never going to be right to talk of there being, for example, ‘two types of people in this world, those who thoughtfully take their shoes off at the door, and those who tramp mud through other people’s houses’.  In fact, in my book I quote whoever it was who said that ‘there are two types of people in this world: those who divide the world into two types of people, and those who don’t’.  I’m with the second party here. 

An example of a very poor dichotomy along these lines would be ‘good drivers’ and ‘bad drivers’.  There is no fundamental difference between the two entities being indicated here.  Almost all ‘good’ drivers sometimes drive badly, almost all ‘bad’ drivers sometimes drive relatively well, and there are a whole host of elements that go to make up good and bad driving.  There just are no such two groups.  We have invented a dichotomy out of a continuum.  It doesn’t make the distinction entirely meaningless, but it is not a good example of a valid dichotomy. 

However there are other continua where a dichotomy is rather more legitimate.  It may not be absolute, but it has meaning because it does point to two underlying phenomena that are different in character, not just more or less of something.  This might be between, for example, left-wing and right-wing philosophies of society.  There is a continuum here, too, but it is between two, in themselves coherent, entities that are readily distinguished in their characteristic forms.  There is more content, and more purpose, to the distinction here (misleading as I agree it can be) than there would be in the case of  ‘good’ and ‘bad’ politicians. 

Then there is a dichotomy based on the existence of two separate phenomena: say, Hinduism and Christianity.  Note I am not saying that there are not people who claim to be both at once (though they must have to go to some mental lengths to achieve this); nor that there may not be commonalities between the world views involved; nor am I saying, of course – God forbid – that there should be any sort of antagonism between them.  I am just drawing attention, for the purposes of argument, to the fact that these are two coherent entities, which undoubtedly have points of overlap, but are generally distinct phenomena – culturally, historically and philosophically.  This is an example of a dichotomy which it would be irrational to disregard, or pretend didn’t exist.  It obviously does. 

There are, of course, all the dangers of those who would misuse the dichotomy to discriminate adversely, or to disadvantage, stigmatise or even attack members of either group.  But that does not imply there is something wrong with the dichotomy.  How it is used is the responsibility of the user, and the situation will not be improved, and could be worsened, by ignoring the existence of a real distinction here. 

Once again let me emphasise: I am not talking about the particulars of these examples.  They are used only as examples.  I am not going to engage in any discussion of issues to do with the content of the examples themselves, that are irrelevant to the point I am making, which is that there are some dichotomies that have no basis, some that have a partial basis in fact, and some that it would be irrational to pretend don’t exist. 

The division of the cerebral hemispheres falls into this last category, a ‘dichotomy’ which it would be profoundly irrational to ignore just because we don’t like dichotomies.  As I have mentioned, evolution has taken care to preserve, and even to intensify, the division of the brain, this organ whose whole purpose is to connect.  The hemispheres differ in their structure and function at every level.  So let’s not say we are dichotomising when we take a look at why that should be. Every intelligent person should want to know why this is the case.  I am not saying I have all the answers, just some suggestions that look pretty good to me, and which are backed by scientific evidence, carefully detailed in my book. 

There may be another type of objection to dichotomy here, though.  It may be accepted that there is a dichotomy, and that it is worth trying to understand its basis, but a fear that this will lead to a ‘dumbed down’ version encouraging simplistic thinking.  At the end of the RSA talk, I confront that point, and I have to say that I don’t know if there’s anything much more I can do to stop that happening in the hands of the wrong people. As Jonathan Rowson points out there, my book is full of nuances and caveats.  But at some point one has to assume one’s audience has got all that by now, and get on with the argument.  In 600 pages it would be hard not sometimes to talk in terms that can be misconstrued, but I do take trouble to point out that the distinction is not absolute, that there is overlap, and so on, as well as that individuals can’t be summed up neatly as ‘left hemisphere’ or ‘right hemisphere’ people, and, above all, that we need both hemispheres, not just one.  At the end of the day, though, there are undoubtedly differences, and in my view they desperately need to be understood.  The last thing we should do is ignore them, because they don’t happen to fit the view of the world we already happen to have.

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