Why, why, does everyone go on so about the brain? Each Tuesday, the New York Times does its section on science, to which I am addicted. I like best the astrophysical stuff on pulsars and quasars and black holes and how old and far away everything is; there’s a pleasantly vertiginous aftertaste that sometimes lasts until ‘Arts and Entertainment’ comes out on Saturday. But I’m quite prepared to settle for the breaking news on whether birds are dinosaurs, or when Africa was last attached to Brazil, or which kind of cholesterol is good for you after all. It’s all grist for the same mill: how odd it is how odd the world turns out to be.
I am, as I say, addicted, and I keep a sharp eye out for trends. Over the last several years, I’ve noticed a striking increase in articles whose common theme is where things happen in the brain. It appears that recent technological developments in ‘neural imaging’ have made it possible to measure the amount of activity that’s going on in a given brain region while a subject is engaged in some experimental task. And, though perhaps not mandatory, it’s natural enough to infer from a reliable correlation between a mental process and a locus of neural activity that the latter is the site of the former. If there’s a place in the brain where you find a whole lot of neurons going off when and only when whoever owns the brain is thinking about teapots, it’s at least plausible, all else being equal, that you’ve found where in that brain its thinking about teapots happens. Likewise, if certain neurons fire at certain frequencies just when a guy is conscious, one might infer that that’s where his consciousness hangs out. All the more so if the correlation holds across subjects.
To be sure, the data aren’t generally quite as clean as you might suppose from made-up examples, and the inferences they are said to suggest are by no means apodictic. But I won’t dispute any of that. I admit, for the sake of the argument, that consciousness is correlated with certain neurons firing at 40 Hz cycles; and that some bits of the brain light up when we hear nouns but not when we hear verbs; and that there are (different) bits that light up when we see a thing, or form its mental image, but not when we hear a thing or describe it to ourselves. It appears there’s even a place in the brain that turns on just when we hear a word that stands for a vegetable; ‘lettuce’ excites it but ‘roast beef’ doesn’t. So be it.
It bears emphasis that there are lots of things other than looking for functional loci that brain scientists do for a living; and that they use lots of experimental techniques other than neural imaging to do them. But it’s functional localisation by neural imaging for which the Times is especially enthusiastic; and I’d guess that as the Times goes, so go the grants. It particularly likes those polychrome maps that show a place in the brain that’s red when you’re thinking about one thing and green when you’re thinking about something else. (Disappointingly, I gather it’s not that the brain turns red or green depending on what you’re thinking about; the colours are computer generated to summarise the levels of neural activity that the experiments discover.) Well, to come to the point, I wonder why the Times cares. I wonder why anybody cares.
I’m old enough not to be surprised when people are interested in things that seem to me not to be interesting: Golf, the music of Andrew Lloyd Webber and the adulteries of politicians are three examples in a plethora. Since, in most such cases, we’re not competing for resources, I don’t mind at all. But science is different. Science is expensive, and it’s largely publicly funded, and there’s never enough money to do all the research that might be worth doing. In particular, brain imaging is expensive compared to other ways of trying to find out about the mind. If you put your money (which is to say: our money) into the elaborate technology required to establish neural localisations of mental functions by imaging techniques, you almost certainly take it out of other kinds of psychological research. Likewise in respect of the time and money that is required to train people to do the science; graduate students, too, are a limited resource. So I’m increasingly concerned when I find that yet another Tuesday has come around, and the Times is still interested in the neural localisation of mental functions and I still can’t figure out why. It occurs to me that maybe we’re heavily invested in finding answers to which we don’t know the corresponding questions. Maybe the availability of the new technology is running the science rather than the other way round. It would hardly be the first time. A research technology tends to develop its own constituency, especially if it is capital intensive. Look upon the space programme and despair.
But I’m a philosopher, not a neuroscientist, so perhaps I’ve badly missed the point. Hence my present attempt to make out what the point that I’ve badly missed might be. I’ll give you some suggestions, not all frivolous, that I’ve heard about why it’s a good thing that science is spending so much time, money and computer power on brain localisation research. I’ll also tell you why none of these suggestions moves me much. Maybe, if I have indeed got it all wrong, someone will correct me by return of post.
I want, to begin with, to distinguish between the question whether mental functions are neurally localised in the brain, and the question where they are neurally localised in the brain. Though I find it hard to care about the second, the first clearly connects with deep issues about how the mind works; ones that even us philosophers have heard of.
For example: there has been, for centuries, a debate going on between people who think that each of the various kinds of mental process is more or less sui generis, and people who think that they are much of a likeness, all consisting of the same elements although differently arranged. With occasional anomalies, the argument between homogeneous minds and heterogeneous minds aligns with the argument between empiricists and rationalists; and, far from being settled, it keeps popping up in unexpected places. Do you think that a classical education disciplines the mind for whatever pursuits it later undertakes? If so, you should think that learning Latin gives rise to intellectual capacities that are more or less equally in play in devising a foreign policy, or designing a bridge, or making money on the market. Similarly, if you think there’s such a thing as ‘general’ intelligence – what IQ tests are supposed to measure – then you should also think that designing bridges and designing foreign policies manifest much the same kind of cleverness, albeit applied to different tasks. People who are good at the one should then be, potentially, equally good at the other. So Veblen held, maybe naively, that society ought to be run by engineers; and Plato held, maybe even more naively, that it ought to be run by philosophers.
Whereas, if you’re on the rationalist side of this debate, you won’t be surprised to find every sort of intellectual sophistication cohabiting with every sort of naivety, and will be disinclined to trust the obiter dicta of experts.
I don’t know who’s right about all that, but it’s easy to see that whether mental functions are neurally localised is likely to be relevant. If the brain does different tasks at different places, that rather suggests that it may do them in different ways. Whereas, if anything that the brain can do it can do just about anywhere, that rather suggests that different kinds of thinking may recruit quite similar neural mechanisms. So empiricists, since they typically hold that all mental processes reduce to patterns of associations, would like the brain to be ‘equipotential’, whereas rationalists, since they think that there might be as many different kinds of thinking as there are different kinds of thing to think about, generally would prefer the brain to be organised on geographical principles. Unsurprisingly, rationalists thought there might be something to phrenology, but empiricists made fun of it. (The empiricists won that battle, of course; but my guess is they will lose the war.)
In any case, I quite see why anyone who cares how the mind works might reasonably care about the argument between empiricism and rationalism; and why anyone who cares about the argument between empiricism and rationalism might reasonably care whether different areas of the brain differ in the mental functions they perform. Likewise for anyone who cares about how much of the mind’s structure is innate (whatever, exactly, that means). If you think a lot of it is, you presumably expect a lot of localisation of function, not just in the adult’s brain but also in the infant’s. Whereas, if you think a lot of mental structure comes from experience (whatever, exactly, that means), you probably expect the infant’s brain to be mostly equipotential even if the adult’s brain turns out not to be. Rationalists are generally nativists and preformationists; empiricists generally aren’t either one or the other.
But given that it matters to both sides whether, by and large, mental functions have characteristic places in the brain, why should it matter to either side where the places are? It’s deeply interesting that there apparently are proprietary bits of the brain in charge of one or other aspect of one’s linguistic capacities. And, no doubt, if you’re a surgeon you may well wish to know which ones they are, since you will wish to avoid cutting them out. But whereas, historically, studies of the localisation of brain functions have often been clinically motivated, I take it to be currently the consensus that they have significant scientific import over and above their implications for medical practice. Very well, then: just what is the question about the mind-brain relation in general, or about language in particular, that turns on where the brain’s linguistic capacities are? And if, as I suspect, none does, why are we spending so much time and money trying to find them?
It isn’t, after all, seriously in doubt that talking (or riding a bicycle, or building a bridge) depends on things that go on in the brain somewhere or other. If the mind happens in space at all, it happens somewhere north of the neck. What exactly turns on knowing how far north? It belongs to understanding how the engine in your auto works that the functioning of its carburettor is to aerate the petrol; that’s part of the story about how the engine’s parts contribute to its running right. But why (unless you’re thinking of having it taken out) does it matter where in the engine the carburettor is? What part of how your engine works have you failed to understand if you don’t know that?
Maybe the Tuesday Times is really some sort of closet dualist. There’s a funny didactic fable of Bernard Shaw’s called, I think, The Little Black Girl in Search of God, in which the eponymous heroine wanders around what was then the intellectual landscape, looking for such wisdom as may be on offer. She runs into Pavlov, who explains to her why he is, rather horribly, drilling holes in the mouths of dogs: it’s to show that expecting food makes them salivate. ‘But we already knew that,’ she says, in some perplexity. ‘Now we know it scientifically,’ Pavlov replies. It may be that some such thought also motivates the current interest in brain localisation. Granted that we always sort of knew that there’s a difference between nouns and verbs, or between thinking about teapots and taking a nap, we didn’t really know it till somebody found them at different places in the brain. Now that somebody has, we know it scientifically.
To put the same point the other way around: what if, as it turns out, nobody ever does find a brain region that’s specific to thinking about teapots or to taking a nap? Would that seriously be a reason to doubt that there are such mental states? Or that they are mental states of different kinds? Or that the brain must be somehow essentially involved in both? As far as I can see, it’s reasonable to hold that brain studies are methodologically privileged with respect to other ways of finding out about the mind only if you are likewise prepared to hold that facts about the brain are metaphysically privileged with respect to facts about the mind; and you can hold that only if you think the brain and the mind are essentially different kinds of thing. But I had supposed that dualistic metaphysics was now out of fashion, in the brain science community most of all. Brain scientists are supposed to be materialists, and materialists are supposed not to doubt that distinct mental states have ipso facto got different neural counterparts. That being so, why does it matter where in the brain their different counterparts are?
To be sure, serendipity is full of surprises and there’s always the chance that something might turn up. It might turn out, for example, that the neural loci of similar kinds of mental process are pretty reliably spatially propinquitous (as, indeed, the phrenologists generally supposed). If that were so, then good brain maps might usefully constrain our hypotheses about psychological taxonomy: if thinking of teapots happened to be side by side in the brain with taking naps, maybe we would then revise our intuition that the two really haven’t much in common. But the issue is academic in the invidious sense since in fact there’s no good reason to think that similarity of psychological functions generally predicts similarity of brain locations or vice versa. And serendipity is a frail reed; if the best you can say for your research strategy is ‘you can never tell, it might pan out,’ you probably ought to have your research strategy looked at.
I once gave a (perfectly awful) cognitive science lecture at a major centre for brain imaging research. The main project there, as best I could tell, was to provide subjects with some or other experimental tasks to do and take pictures of their brains while they did them. The lecture was followed by the usual mildly boozy dinner, over which professional inhibitions relaxed a bit. I kept asking, as politely as I could manage, how the neuroscientists decided which experimental tasks it would be interesting to make brain maps for. I kept getting the impression that they didn’t much care. Their idea was apparently that experimental data are, ipso facto, a good thing; and that experimental data about when and where the brain lights up are, ipso facto, a better thing than most. I guess I must have been unsubtle in pressing my question because, at a pause in the conversation, one of my hosts rounded on me. ‘You think we’re wasting our time, don’t you?’ he asked. I admit, I didn’t know quite what to say. I’ve been wondering about it ever since.