ADAPTING MINDS Evolutionary psychology and the persistent quest for human nature David J. Buller

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1 Monday 01 August 2005 IN THIS WEEK'S TLS The selfish gene pool Jerry Fodor 27 July 2005 ADAPTING MINDS Evolutionary psychology and the persistent quest for human nature David J. Buller 550pp. MIT Press (US $34.95) Full story displayed On my bad days, I sometimes wonder what philosophers are for. Philosophers used to believe they had a proprietary method that reveals proprietary truths, but that is increasingly hard to credit. Nobody has been able to say what the method is, while the proprietary truths have been thin on the ground. There are, to be sure, a fair number of traditionally philosophical problems: scepticism, freedom of the will, the nature of the mental, the objectivity of the moral, the a priori, the modal, justification, induction and so on. But millennia of arguing these topics have now flowed under the bridge, and all the plausible positions seem already to be occupied; to say something new you have to say something outrageous. (I gather that much the same is true in Shakespeare criticism: Prospero was senile, Rosalind was queer, Goneril was a feminist that sort of thing.) I m happy to report, however, that books like David J. Buller s Adapting Minds go some way towards dispelling the gloom. Philosophers are trained to criticize arguments. Very well, there are plenty of arguments out there aching to be criticized; let s have a look at them. Buller, perfectly sensibly, has decided to keep busy by minding other people s business and not worrying much about whether he is really doing philosophy. Good on him. Adapting Minds is an extended critical discussion of the Evolutionary Psychology movement. Evolutionary Psychology (when spelled with capitals) is the name of a galaxy of empirical theses including the idea that our minds are massively modular (they consist of a bundle of functionally autonomous, special-purpose, or domain specific information processors); that quite a lot of our psychological organization is innate (1 of 10)8/1/ :23:27 AM

2 ( Nativism ); and, crucially, that much of it is an adaptation to selection pressures that operated in the ancestral conditions in which our minds evolved. The affinities are with Sociobiology, of which Evolutionary Psychology (EP) is a more respectable descendant. Accordingly, Buller s book comes in two parts. The first is an exposition and criticism of the various theses that compose EP; the second is a detailed examination of the data that have been offered in support of it. I think Buller generally gets the exposition right, though, by my lights, he s often on the wrong side of the issues. For example, Bullerhe is an anti-nativist. He thinks that learning from experience is accomplished by the operation of some more or less general purpose, topic-neutral cognitive mechanism. This is, of course, the kind of view Empiricists have held for centuries. What s always been lacking is a serious account of what a generalpurpose, topic-neutral learning mechanism would be like; one that is compatible with the traditional Rationalist observation that we apparently know more than our environment tells us. Buller has a candidate that he thinks is neurologically plausible, but he offers no reason to believe that his kind of Empiricism will work better than the kinds that have failed. If you were a Nativist when you started reading Buller, you will find your faith unshaken at the finish. (Buller can be very unconvincing when he puts his mind to it. Consider since Homo sapiens is an individual, not a natural kind, there is no such thing as human nature. How many questions would you say this begs?) What bears emphasis, in any case, is that Buller has no objection to the central thesis of EP, namely that much of our mental structure is an evolutionary adaptation to the ancestral environment in which our kind evolved. To the contrary, Buller is himself explicitly an Adaptationist; his quarrel with EP is mostly about exactly which adaptations it is that our minds exhibit. For example: it is a typical EP thesis that women have an inherited interest in conjugal fidelity that functioned, back in hunter-gatherer times, to ensure them of helpmates for child rearing. Buller thinks, by contrast, that women have an inherited interest in conjugal fidelity that functioned, back in hunter-gatherer times, to ensure them of reliable opportunities for mating. But Buller and his antagonists agree that women have an inherited interest in conjugal fidelity, and that the interest they have is an evolutionary adaptation. In short, Buller grants EP its adaptationism, which is what I take to be precisely the thesis that most begs for critical discussion. He has, in my view, come down with the malady that he undertook to cure. More about this presently. The second part of Buller s book, a critical review of the empirical data that have been offered in support of EP, does what has needed doing for years: it makes clear how exiguous these data are. Buller goes through the classical results, showing pretty convincingly how often they are inconclusive with respect to the theses they are alleged to support. His discussion is worth considering in detail; sometimes it s fully persuasive, sometimes not. One ought to bear in mind, after all, how hard it is to evaluate empirical claims about the psychology of creatures that are long since dead. Minds don t, of course, leave fossil records; and you (2 of 10)8/1/ :23:27 AM

3 can t do experiments on extinct animals. Still, I think Buller is very likely right on balance: much too much has been made of much too little. The only empirical findings I ve been personally involved in examining are widely supposed (in EP circles) to show that we have an innate, modular cheater detection mechanism that evolved to monitor social exchanges when our Pleistocene ancestors lived in small groups of hunter-gatherers. (These findings are, by the way, the sole experimental results so far that are even alleged to exhibit the adaptivity of a specifically cognitive mental trait.) Buller is pretty sure that they are an experimental artefact; and I m pretty sure that he s right. So that s all very useful. Still, I think Adapting Minds is, in important respects, a lost opportunity; there s this elephant aboard that Buller appears not to have noticed. For reasons I ll now turn to, I think that something is radically wrong with the whole attempt to treat beliefs, desires, hopes, goals, intentions and the like as evolutionary adaptations. You just can t merge an Adaptationist account of evolution with the kind of psychology that says that we act out of our beliefs and desires; not, anyhow, in the way that EP proposes to do. Since the argument that you can t is conceptual rather than empirical, it s one that you might have thought that a philosopher would attend to when he joins the discussion. In relatively untendentious Adaptationist explanations ones that don t involve the evolution of the mind the situation is something like this: one finds some heritable feature of a creature s phenotype (for example, opposed thumbs, complex eyes, sexual dimorphism; whatever) and then constructs a story about how developing the feature would have increased fitness (here understood as an ancestor s probability of contributing to the gene pool of his breeding group) in the environment in which the creature evolved. The logic of Adaptationist explanations in EP accords with this general pattern: the datum is that a certain kind of creature reliably exhibits a certain kind of behaviour; and the putative explanation attributes the behaviour to a psychological mechanism typically a complex of beliefs and desires that would have been selected for in the ancestral environment. Roughly: on the one hand, the behaviour is intelligible on the assumption that the creature acts out of a certain motive; and, on the other hand, a propensity to act out of that motive would have been selected for if the evolutionary ancestors had had it. The point to keep your eye on what distinguishes Adaptationism as applied to specifically mental traits is that the explanations it has on offer incorporate the kind of reasoning in which a creature s behaviour is explained by reference to its beliefs and desires. So you can t so much as start on constructing this kind of explanation unless you know not just how a creature behaves, but also its motive for behaving that way. This introduces complications that are not found in Adaptationist theorizing outside psychology: complications to which Evolutionary Psychologists Buller included are pretty generally insensitive. Here s one: it s often perhaps always true that there are any number of ways of (3 of 10)8/1/ :23:27 AM

4 construing behaviour as the outcome of beliefs and preferences. Jones is observed to carry an umbrella; well, perhaps he thinks it will rain and desires not to get wet. Or perhaps he thinks it won t rain, but he s past due to return the umbrella that Smith loaned him. Or perhaps Jones has no particular end in view at all; he just likes carrying umbrellas. Or perhaps he just likes carrying this umbrella. And so forth. Let s pretend, for the sake of the exposition, that we think that Jones s carrying his umbrella is the manifestation of an adaptation, and that we are seriously trying to explain the behaviour as such. If so, then it matters a lot in deciding which Adaptationist story to tell what we think Jones s motive was. If his motive was to keep dry, we need to show that a preference for not getting wet would have been selected for in Jones s ancestral environment. If his motive was to return what he had borrowed, we need to show that an inclination to pay their debts would have conduced to his ancestors reproductive success. And so on, once again. Well, then: how are we to establish the motive for the behaviour we are trying to explain? In the most transparent case, we might just ask Jones. If he is compliant and sincere, he ll tell us why he s carrying his umbrella, and we can then get on with the question Evolutionary Psychologists really care about: whether behaving with the motive he avows would have helped his ancestors to reproduce. There are, however, several reasons why the fully transparent case isn t typical of the ones that Evolutionary Psychologists actually encounter. For one thing, Jones may not be reliable about his motivation. Perhaps his motive was unconscious: he carried his umbrella with malice aforethought all right, but he can t, for the life of him, tell you why. Unconscious motives (if, indeed, there are such things) complicate the Adaptationist s problem, but, arguably, they don t make it intractable. If Jones can t tell us why he had his umbrella in tow, we can always ask his analyst. At worst, we can make an educated guess. It s more of a problem and Buller is quite clear on this that an Adaptationist account of Jones s behaviour may need to appeal to a motive that explains his action but that Jones didn t actually have; not consciously, not unconsciously, not at all. It s a main tenet of psychological Darwinism that the ultimate motivation for an adaptive behaviour is to maximize one s relative contribution to the genetic endowment of one s breeding group. So (still assuming it s an adaptation) what Buller calls the proximal cause of Jones s behaviour is that he wants (maybe consciously, maybe not) not to catch his death of cold and he believes (maybe consciously, maybe not) that he won t catch his death of cold if he doesn t get wet. But the ultimate cause of his behaviour is his wanting to maximize his contribution to the gene pool of his breeding group, which requires, inter alia, that he not be dead. That, to repeat, is what Jones really wants, assuming that his umbrellacarrying behaviour is an adaptation; and it s what his ancestors were selected for wanting in the old days back on the savannah. The trouble is, of course, that Jones wants no such thing not consciously or unconsciously either. Jones may never have so much as heard about breeding groups; his ancestors certainly never did. So, really, what are we to make of motives that explain one s actions even though one (4 of 10)8/1/ :23:27 AM

5 doesn t have them? And who is it that is motivated by Jones s genotypic ambitions if it isn t Jones? Notice, once again, that this is a kind of puzzle that is proprietary to Psychological Adaptationism; it doesn t arise for evolutionary explanations of the opposed thumb, or of bipedal gait, or of the anatomy of the retina; that s because neither your motivations, nor your ancestors, nor anybody else s, come into the story about why thumbs work the way they do. It s Psychological Adaptationism, not Adaptationism per se, that is raising this spectre of unattached motives. The canonical Evolutionary Psychology literature contains a number of ideas about how a creature s behaviour might be explained by attributions of motives that it doesn t have. I confess that they seem to me to be simply bizarre. Daniel C. Dennett suggests that, if Jones s behaviour is an adaptation, then it s (not Jones but) Mother Nature who is concerned about his contribution to the gene pool. But you might as well blame the Easter Bunny. There isn t any Mother Nature; and if unattached motives can t explain behaviour, neither can the concerns of fictitious persons. Richard Dawkins suggests that, if Jones s behaviour is an adaptation, then it must be (not Jones but) Jones s selfish genes that wish to maximize reproductive success. Steven Pinker seems to have swallowed Dawkins whole. "Dawkins explained the theory.... People don t selfishly spread their genes, genes selfishly spread themselves. They do it by the way they build our brains.... Our goals are subgoals of the ultimate goal of the genes, replicating themselves.... The confusion between our goals and our genes goals has spawned one muddle after another." It has indeed. As I say, Buller is aware of the need to avoid that sort of solecism. Passages like the following recur: "[Evolutionary Psychologists] in no way think that parental psychologies have been designed to process information about reproductive value and relatedness.... Our motivational systems can be designed to cause us to act in ways that enhance our reproductive success without processing information about reproductive success." But that doesn t cut the knot since, strictly speaking and theology aside, nobody did design our motivational system; like Topsy, it just growed. How, then, is the talk of its having been designed to cause us to act in ways that enhance our reproductive success supposed to be construed? No doubt our motivational systems are, often enough, causally implicated in our reproductive successes. But what something causes is one thing; what it is designed to cause is quite another. The point is entirely general. The structure of our nervous system is part of the etiological story about our migraines. It doesn t follow that our nervous system was designed to give us migraines; it doesn t follow, and it isn t true. This sort of playing fast and loose with the notion of design is, notoriously, the soft (5 of 10)8/1/ :23:27 AM

6 underbelly of Adaptationism. The more Buller explains his views, the more mysterious they seem: "saying that marriage evolved as an exchange of paternal care for paternal certainty or parental opportunities does not mean that ancestral members of either sex were consciously or unconsciously motivated by a desire [for either].... Hypotheses about the evolution of marriage are not hypotheses about... motives... they are hypotheses about the beneficial effects of marriage. " Buller also says that insofar as we have motives that impel us to commit to marriages, Evolutionary Psychology seeks the ultimate causes of these motives..... But none of that will do. Familiar example: it s a beneficial effect of my having a nose that it helps to support my glasses (thereby contributing, indirectly, to such reproductive successes as I ve managed to scrape together). But nobody, the Easter Bunny included, designed my nose. A fortiori, my nose wasn t designed to support my glasses. Of course it wasn t. In fact, it goes the other way around: my glasses were designed to be supported by my nose. There s no mystery about that; my glasses literally and unmysteriously had a designer; and that the glasses he designed should be supported by noses like mine was, literally and unmysteriously, part of what he had in mind when he designed them. Notice, in particular, that our glasses are designed to be supported by our noses whether or not our noses actually succeed in supporting them. It belongs to the logic of designs, goals, motives and the like, that you can t infer the effects intended from the effects produced. This is a stumbling block for EP, as we ll see in a moment. The problem about how a creature could act out of an unattached motive implies a problem about how to distinguish what s (merely) selected from what s selected for when traits of mind evolve. Or (to put it in terms Buller often uses) how to distinguish mental traits that really are adaptations from mental traits that are only by-products of adaptations. This is no small matter: on the one hand, the logic of evolutionary explanations in psychology (and elsewhere) requires distinguishing adaptations from their merely incidental effects; it s only the former that are supposed to have been selected for. On the other hand, it s quite plausible that when the adaptation at issue is psychological, the required distinction can t be drawn without fudging. I ll run through a case that I suppose nobody ever actually worries about, but which may serve to illustrate the problem. Why does copulation thrive so? I mean, there does seem to be a lot of it around, so what s in it for people who do it? Here are two different kinds of answers: the first is, I suppose, the sort that common sense commends; the second is the sort that an Evolutionary Psychologist might well be imagined to offer. First proposal: we copulate a lot because we like it a lot; we do it for its own sake. It s a virtue of this suggestion that it makes no appeals to unanchored motives. It doesn t suppose that there s any end that we copulate in hope of achieving; that our interest in copulation is somehow instrumental. In particular, it doesn t suppose that we copulate because our unconscious (or the Easter Bunny, or a selfish gene) wants us to have more children. Second proposal: copulation is (6 of 10)8/1/ :23:27 AM

7 an adaptation. We copulate with further ends in view; we copulate in order to propagate our genotype. It is, to be sure, a bit unclear in whose minds these further ends are in view. Quite likely not ours; maybe our genes ; maybe the Easter Bunny s. I m about to consider how the dialectic between these answers might play out. First, however, I want to call your attention to a difference between the question about copulation and the question about Jones. It s not clear how, if at all, the differences between the various proximal motives that Jones may have acted on would affect his reproductive success (or, mutatis mutandis, how they would have affected the reproductive successes of his evolutionary ancestors). Maybe one has more children if one carries one s umbrella in order to avoid getting wet; or maybe one has more children if one carries one s umbrella in order to discharge one s debts. But the question is moot; all that matters to whether his behaviour is an adaptation is that Jones will have more children if he carries his umbrella than if he doesn t (all else equal). In the copulation case, however, the cards are on the table. What motivates one s copulations just doesn t matter at all to how many children one has; you end up with the very same number whether you copulate for fun or because you want to make an heir. In effect, there s a tie. That being so, is one s interest in copulation a by-product of one s interest in reproduction? Or does it go the other way around? I think that it s a matter of principle that this sort of question can t have an answer when the motives are unanchored. Correspondingly, it favours the first proposal, as opposed to the second, that it doesn t raise this sort of question. The moral, in any event, is that one can t simply stipulate that the unanchored motive that evolution selected for (in contrast to the ones that it merely selected) is whichever would maximize reproductive success. Not, anyhow, in a case where the reproductive consequences of a behavioural disposition don t depend on what motivates the behaviour. I hope you won t think I asked the question about whether copulation is an adaptation in a spirit of frivolity. To the contrary, I think the issue it raises casts doubts on the whole project of applying the Adaptationist paradigm to the explanation of psychological traits. EP says that behaviour is adaptive if there is some effect that it was designed to have; and the effects that adapted behaviours were designed to have are the ones that would have contributed to reproductive success in the ancestral environment. My puzzle arose because, on the one hand, the alleged adaptation is our motive for copulation; and, on the other, the motive for copulation just doesn t affect its reproductive consequences. But, on second thought, that isn t really just a puzzle about copulation. Rather, it s part and parcel of belief/desire explanations as such; it pertains to what philosophers call the intentionality of motives, plans, designs, goals and the like. The behaviours that such things cause invariably have unintended effects, but it s only the effects that the behaviour was intended to have that are relevant to the identity of a motive. Having climbed up the hill Jack fell down and broke his crown and Jill came tumbling after. But we have it on good authority that Jack s motive in climbing up (7 of 10)8/1/ :23:27 AM

8 the hill wasn t to fall down it, or to break his crown, or to tumble Jill. His motive was to fetch a pail of water; the falling down was just an unintended consequence. So, then, is a propensity for hill-climbing an adaptation or isn t it? According to EP, that depends on what effects such a propensity had (or would have had; or would probably have had) in the ancestral environment; specifically, whether it was reliably a cause of reproductive success. But that simply can t be right: propensity for works like designed to, wants to and the rest; what propensity a behaviour manifests just isn t a question of what effects it has. Since these include, inter alia, the effects of the propensity on reproductive success, it follows that its effects on reproductive success can t be what decides whether a mental propensity is an adaptation. That just isn t the way that belief/ desire explanations work. It s the last of these claims that I want to emphasize. The project of Evolutionary Psychology is to exhibit propensities for acting out of beliefs and desires as adaptations. Well, it can t be done. Not, anyhow, so long as adaptive propensities are, by stipulation, ones that increase the likelihood of having children (or that would have done so, Back Then). That sort of story may work when the traits in question are morphological; there are those who think it does and there are those who think it doesn t. But, to repeat one last time, it can t work when the propensities are intentional in the philosopher s sense of that term. The intentional content of the mental propensity that one s behavior manifests ( what you had in mind in behaving as you did) can t be reconstructed from the effects of the behaviour; that s true of proximal and ultimate propensities indifferently. Suppose there s a question about whether you like marriage because it s nice having a spouse to help with the children, or whether you like marriage because you want to maximize your opportunities for breeding. That question just can t be decided by determining which motive would have led to reproductive success in the ancestral environment. It just can t be; that s not the way that belief/desire explanations work. (Or have I mentioned that?) Why don t Evolutionary Psychologists pay attention to this? Why doesn t it keep them awake at night? Perhaps it s because they think they know a way out. True, your motives don t matter to the reproductive success of your copulations so long as copulation and reproduction are reliably linked. But ask yourself what happens if the connection is broken. Or rather, what would have happened if the connection had been broken in the ancestral environment? Would copulation have thrived then all the same? Counterfactual hypotheticals are notoriously hard to evaluate, but I should think that of course it would; so, anyhow, our current enthusiasm for birth control strongly suggests. Appealing to counterfactual disconnections breaks the tie all right, but apparently not in the direction that Adaptationists want. Ah, but, comes the reply, the situation that you re imagining wouldn t have what we call evolutionary stability. You forget that, if the connection between copulation and reproduction had broken, those of our ancestors who continued to copulate regardless wouldn t, in fact, have become our ancestors (or anybody else s). Instead, they would eventually have become extinct. Evolution would have selected against them in favour of rivals who spent (8 of 10)8/1/ :23:27 AM

9 their time more (re)productively. This is, no doubt, the crux; but I really don t think that it gets Adaptationism off the hook. For one thing, there were no such rivals for our ancestors to compete against; and evolution can t select for the behaviour of merely counterfactual competitors. For another thing, as many biologists have rightly insisted, it s whole organisms, not their individual traits, that evolutionary pressures select or reject. That being so, a creature has room for discretionary indulgences so long as it continues to be viable on balance. There isn t, in fact, the slightest reason to suppose that our ancestral evolutionary niche was so narrow that it left no room for occasional uninstrumental copulation. Maybe, indeed, we were so good at hunting and gathering Back Then that there was often time at the end of the day for recreational copulation. Perhaps that wouldn t have caused our extinction after all. The real issue is the biological plausibility of pluralism about motives; it s whether biology entails that, in some sense or other, there is only one goal that we ever pursue. One can imagine selection pressures so intense that no trait survives unless it conduces to reproductive success: but is there any reason at all to suppose that those were the conditions under which we evolved? To the contrary, as far as anybody knows, it looks like we ve been singing for fun and dancing for fun and painting for fun and gossiping for fun and copulating for fun right from the start; there isn t, to my knowledge, the slightest shred of evidence to the contrary. It s not, in short, part of the scientific world-view that only mental traits that favoured reproductive success would have survived in the ancestral environment. The scientific world-view does not entail that writing The Tempest was a reproductive strategy; that s the sort of silliness that gives it a bad name. First blush, there seem to be all sorts of things that we like, and like to do, for no reason in particular, not for any reason that we have, or that our genes have; or that the Easter Bunny has, either. Perhaps we re just that kind of creature. Over the years, people keep proposing theories that go: what everybody really wants is just... (fill in the blank). Versions fashionable in their times have included: money, power, sex, death, freedom, happiness, Mother, The Good, pleasure, success, status, salvation, immortality, self-realization, reinforcement, penises (in the case of women), larger penises (in the case of men), and so on. The track record of such theories has not been good; in retrospect they often look foolish or vulgar or both. Maybe it will turn out differently for what everybody really wants is to maximize his relative contribution to the gene pool. But I don t know any reason to think that it will, and I sure wouldn t advise you to bet the farm. (9 of 10)8/1/ :23:27 AM