could sexual selection have made us psychological altruists?

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Stud. Hist. Phil. Biol. & Biomed. Sci. 39 (2008) 153–162

and Philosophy ofBiological andBiomedical Sciences

Could sexual selection have made us psychological altruists?

Tom Walker

Centre for Professional Ethics, Keele University, Keele, Staffordshire ST5 5BG, UK

Received 30 July 2006; received in revised form 6 March 2007

Abstract

Psychological altruism (being motivated by the needs of others) has a tendency to produce behaviour that is costly in evolutionaryterms. How, then, could the capacity for psychological altruism evolve? One suggestion is that it is the result of sexual selection. Thereare, however, two problems that face such an account: first, it is not clear that the resulting behaviour would be altruistic in the relevantsense, and second, it does not seem to fit with key features of our actual helping behaviour. I will argue that both of these problems canbe avoided if we adopt a modular account of desire formation.� 2007 Elsevier Ltd. All rights reserved.

Keywords: Sexual selection; Psychological altruism; Modular mind

When citing this paper, please use the full journal title Studies in History and Philosophy of Biological and Biomedical Sciences

1. Introduction

As Gregory Kavka has pointed out, being motivated bythe interests of others has a systematic tendency to producebehaviour that helps those in need, behaviour that tends tobe costly for the actor (see Kavka, 1986, p. 61). When thosewho have the capacity to be motivated in this way comeacross someone in danger, they will have some motivationto rescue them; and when they come across those who arestarving they will have some motivation to feed them. Ofcourse, they may not always act on that motivation. But,on those occasions when they do, they decrease, by how-ever small an amount, their own chances of survival. Shar-ing resources with those who lack them, for example,means that these resources are not available should theybe needed later—a particular problem where resources

1369-8486/$ - see front matter � 2007 Elsevier Ltd. All rights reserved.

doi:10.1016/j.shpsc.2007.12.006

E-mail address: [email protected] Prominent among people who hold this position are supporters of psycholog

For a review of the history of this theory, and attempts to show that it is fals

are scarce or are likely to become so. Those who lack thecapacity to be motivated by the interests of others willnot take these risks to the same extent (although that isnot to say that they will not take them where they see somepersonal benefit in doing so). In each generation, therefore,those with this capacity will be more likely to help others ina way that damages their own chances of survival thanthose who lack it. As a result the proportion of the popu-lation with the capacity to be motivated by the interests ofothers will go down over time. Given enough time it will beremoved from the population entirely.

If this story is correct, then it would provide strong sup-port for those who hold that we are not capable of beingmotivated by the interests of others.1 But is it correct? Afirst step in challenging it may be to note that the helpingbehaviour it describes is not only altruistic in the sense that

ical egoism, the theory that the only thing that motivates us is self interest.e, see Batson (1991) and Sober & Wilson (1998), Part II.

mailto:[email protected]

154 T. Walker / Stud. Hist. Phil. Biol. & Biomed. Sci. 39 (2008) 153–162

it is motivated by the interests of the individual being helped(which I will call ‘psychological altruism’), but also in amore technical sense (which I will call ‘evolutionary altru-ism’).2 Within evolutionary biology an act is described asaltruistic if it has the effect of decreasing the actor’s fitnesswhile increasing the fitness of others (see Wilson & Dugat-kin, 1992, pp. 29–33). Going to rescue someone in danger,or sharing your resources with those in need, both seemto be altruistic in this more technical sense. In this theyare not alone. Behaviour that appears to be altruistic inthe evolutionary sense is widespread in the natural world.Biologists have taken a variety of strategies when tryingto account for it. They have, for example, variously argued:1) that far from reducing your chances of surviving, helpingmay actually increase them (this is the strategy taken byadvocates of both reciprocal altruism3 and group selection4

accounts); 2) that while helping may reduce the helper’schances of surviving, it may at the same time increase thechances that their close relatives will survive, and so spreadin this way (the approach taken by advocates of kin selec-tion accounts5); 3) that helping may have been selectedfor precisely because it is costly (the line taken by sexualselection theorists). Each of these approaches has had somesuccess in accounting for evolutionary altruism in non-humans. This raises the possibility that one or more of themcould account for psychological altruism as well.

What I want to do here is to focus entirely on the thirdoption: sexual selection. I will argue that it can account forthe human capacity for psychological altruism, but to do soit will need to make use of a particular idea about how themind is structured. It is important to note here that parts ofthis argument will be highly speculative. As such, I am notclaiming to have shown that psychological altruism inhumans exists and was produced by sexual selection.Rather, my aim is more limited, being simply to show thatour capacity for psychological altruism could have beenproduced by sexual selection.

2 For discussions of the difference between these two types of altruism, see K128–129; Sober & Wilson (1998), p. 6.

3 The basic idea behind Robert Trivers’s theory of reciprocal altruism is thaapparently altruistic acts (see Trivers, 1971). For instance, vampire bats shareThe recipient of the food benefits, but so does the bat who gives the food. Whenit has helped. Bats who give are bats who receive. Thus, in the long term helping1988). In reciprocal altruism, then, the helper appears to be altruistic if we conwhole history of the interactions between these two creatures we see that in heloverall effect of helping is actually to increase the helper’s own fitness.

4 The central idea of group selection is that individuals who live in groups whthan those that live in groups where they do not (Sober & Wilson, 1998). Thoseto survive and reproduce (because they are more likely to be helped when thebenefit could tip the balance so that an individual will have a better chance of susince they will then get the benefits of living in a group of altruists. Where th

5 Kin selection theory makes use of William Hamilton’s idea of inclusive fit

selected for. Inclusive fitness is obtained by taking the fitness of an individual anthe fitness of others, in each case devalued by an amount (known as the regresalso inherited the trait (Hamilton, 1996, p. 336). Because there is a good chanceindividual’s fitness could nevertheless increase its inclusive fitness. This willindividual’s close relatives is large enough to outweigh any negative effects onpopulation with that trait in each succeeding generation will actually increase. Iselected for, because while it decreases an individual’s fitness, it may actually

2. Sexual selection

Rather than focusing on survival, sexual selectionaccounts start from the idea that, for sexually reproducingspecies, the number and quality of mates that an individualcan attract will have a major affect on their reproductivesuccess. As a result those traits that increase an individual’schances of attracting potential mates will, all else beingequal, tend to spread through the population. Some thingsselected for in this way will aid survival. But, as AmotzZahavi has argued, when it comes to the sexual selectionof traits, high cost, far from being a disadvantage, canactually be a desirable feature that is positively selectedfor (see Zahavi, 1975). The reason for this is that costlytraits are hard to fake, their high cost serves as a guaranteethat the individual concerned actually has the desired trait.In contrast, choosing sexual partners on the basis that theyhave a cheap trait leaves one open to being fooled. Suchtraits are relatively easy to fake and as a result there is avery real chance that any sexual partner you select maynot actually possess the desired trait after all.

Helping others, particularly non-relatives, appears to begood way to demonstrate that an individual has access toresources and is biologically fit. It is also hard to fake;you can only help if you actually posses the resourcesand strength needed to do so. As a result, it is just the sortof trait that may be picked up on, and selected for, by sex-ual selection. This indeed appears to be what has happenedamong the Arabian Babblers studied by Amotz and Avi-shag Zahavi (see Zahavi & Zahavi, 1997, Ch. 12). Not onlydo these birds behave in ways that appear altruistic in theevolutionary sense—sharing food with non-relatives, act-ing as sentries, and mobbing predators to drive themaway—they seem to compete to do so. Zahavi and Zahaviargue that this behaviour, which is otherwise hard toexplain, is the result of sexual selection. Only very fit indi-viduals can afford to win the competition to be altruistic.

itcher (1985), pp. 396–406; Kavka (1986) Section 2.4; Sesardic (1995), pp.

t in many cases both the helper and the helped benefit from the former’sfood with members of their roost who have been unsuccessful in hunting.it, in turn, has been unsuccessful in hunting it will receive food from thosebenefits those who give the help as well as those who receive it (Wilkinson,centrate on a particular instance of their behaviour. But if we look at the

ping they benefit themselves. That is, where there is reciprocal altruism the

ere they share a particular trait may be better able to survive and reproducewho live in groups where individuals help those in need will be more likely

y need it) than those who live in groups where this does not happen. Thisrviving and reproducing if they are altruistic than if they are non-altruistic

is happens evolution by natural selection will favour altruists.ness to argue that evolutionary altruism towards close relatives could bed adding all the effects of having a particular trait on its own fitness and onsion coefficient) which reflects the chances that the individual affected hasthat close relatives have inherited the same traits, a trait which decreases anhappen whenever the beneficial effects of that trait on the fitness of anits own fitness. The overall effect will then be that the proportion of the

n this way a trait like evolutionary altruism towards close relatives could beincrease their inclusive fitness.

T. Walker / Stud. Hist. Phil. Biol. & Biomed. Sci. 39 (2008) 153–162 155

Their success in doing so leads to higher status, which inturn increases their chances of mating with high fitnessindividuals.

Could something similar be true for humans? IrwinTessman, Geoffrey Miller, and Amotz Zahavi have allargued that it can (see Tessman, 1995; Miller, 2000, Ch.9; Zahavi, 2000). On Zahavi’s account, just as with theArabian Babblers, helping makes us more likely to attractsexual partners via its effects on our status—helpingincreases status, and higher status individuals are moreattractive to potential mates. In contrast, status does notplay a role on either Tessman’s or Miller’s account. Tess-man argues that altruism demonstrates the ability andthe intention of the altruist to be a reliable mate and par-ent. Because helping others imposes a cost on the helper,the extent to which a potential partner helps others givesan accurate indication of these qualities. Once people havestarted to select mates, at least partly, on the basis of howmuch they help others, there will be sexual selection forthose who help. On Miller’s account helping others is sim-ply a way of demonstrating biological fitness. Only thosewho are fit can afford to act altruistically. The more altru-istic they are the fitter they need to be. So, the offspring ofthose who mate with altruists would be more likely to sur-vive and reproduce than the offspring of those who matewith non-altruists. In this way sexual selection could selectfor helping behaviour that is costly to the helper.

On all of these accounts there has been selection forhelping behaviour because helping others is an accurateadvertisement of qualities that are desirable in potentialmates. Some support for such accounts comes from the factthat in all thirty-seven cultures investigated in David Buss’sstudy of sexual preferences both men and women rated‘kindness’ as one of the features that they found most desir-able in potential sexual partners (Buss, 1989; Miller, 2000,p. 292). This suggests that among humans there may wellbe some advantage in being helpful to those aroundyou—by doing so you are likely to be displaying behaviourthat others find attractive. What is more, Miller argues thatseeing helping behaviour as the result of sexual selectionenables us to explain otherwise puzzling features of theway we help others. For instance, when giving to charitypeople appear to be relatively unconcerned about the effi-ciency of the charities they give to. They do not, in general,seek out those where their donation will do the most good.But they do appear to be concerned about being seen to becharitable. In most cases to get people to donate to yourcharity they need to be given some token to show that theyhave done so. And people tend not to give to charities thatno-one else has heard of (Miller, 2000, pp. 321–325). Thesefeatures make sense if there has been sexual selection forhelping others. The evolved mechanism that enables us tobe motivated by the needs of others will then have beenshaped by the need to demonstrate that we have done so.Giving to charity will demonstrate that we have resourcesto spare even if the charity we give to is inefficient, butnot if no-one knows that we have given. Thus, the motiva-

tion to help will be affected by whether or not we are seento have helped far more than by the efficiency of the helpwe provide.

3. Two problems

At the heart of sexual selection accounts of altruism, aswe have seen, is the idea that helping is beneficial because itis a way to demonstrate that we have certain qualities,qualities that members of the opposite sex find desirablein potential mates. How effective helping is at demonstrat-ing these qualities will depend, in part, on the visibility ofthe help given (at the extreme, helping that no-one knowsabout does nothing to demonstrate your qualities), and,in part, on the cost of that help (the more valuable thethings you have to give up to help, the better helping isas a display). Different systems for producing helpingbehaviour will vary in how sensitive they are to these fac-tors, and hence in how good they are at producing behav-iour that effectively demonstrates that the actor has thosequalities. As a result we would expect that sexual selectionwill not only produce systems that result in us helping, butthat it would also tend to favour some of those systemsover others. In particular we would anticipate that sexualselection will produce systems that are sensitive to how vis-ible help will be and to the cost of helping, but may not besensitive to considerations about the effectiveness of thathelp (as, on its own this does not affect how well helpingworks as a display). This is the very prediction that Millermakes use of in arguing that the way we give to charitiesprovides support for his argument that sexual selectionhas been the process that produced human altruism.

That sexual selection would favour systems of this type,however, produces two problems for any account ofhuman psychological altruism that depends on the ideathat helping is a way to attract potential mates. The firstis that when we look at the overall pattern of human help-ing we do not find the pattern of behaviour that sexualselection accounts would predict. The second is that it isnot clear that such behaviour is altruistic in the relevantsense. From Thomas Hobbes onwards philosophers haveused the idea of helping as a display to support the claimthat psychological altruism simply does not exist (for Hob-bes’s own position, see Hobbes, 1968). The idea being thatwhen we help others we are motivated to do so, not by theirneeds, but solely by a desire to further our own ends byshowing that we have some desirable quality. Let us takethese in turn.

Although the idea that there has been sexual selectionfor helping may make sense of our behaviour when givingto charity, it appears that it cannot be a complete accountof why we help others. This is partly because, on the sexualselection account, helping should reflect the ability to helpas a way of demonstrating some desirable property (fitness,say, or suitability as a parent). This, in turn, appears to ruleout the possibility that people would help in ways thatdestroy that property—such as helping where they know


doing so will lead to their death. But we know that thissometimes happens. Think of those soldiers who, by throw-ing themselves on a grenade, save the lives of their com-rades. It is also partly because, as Simon Blackburn haspointed out, if humans are to be interpreted as consciouslyor unconsciously pursuing their genetic success we wouldexpect that people would be more likely to go to the aidof others when there are more people around to beimpressed (Blackburn, 1998, p. 149). The same seems tobe true if the ability to be motivated by the needs of othershas evolved as a way of demonstrating our own properties.In that case also we should be more likely to help whenthere are more people around to view our display. But ina series of psychological experiments, Bibb Latane andJohn Darley have demonstrated that people are actuallyless likely to go to the aid of those who need help whenthere are other people around.6 This is known as thebystander effect and, as Blackburn argues, it appears topose a serious problem for any account of our helpingbehaviour that appeals to helping as a display of somekind, as sexual selection accounts do.

The problem for sexual selection accounts posed by thebystander effect is that the larger the audience the betterhelping appears to be as a display. Of course, helping infront of any audience would be a better display than help-ing where no-one will know that you have done so. As suchwe might anticipate, that where sexual selection is thesource of the mechanisms that produce helping behaviour,helping would be restricted to occasions where at leastsomeone will know about it. This appears to be a point thatMiller, for one, accepts. For instance, when discussing giv-ing to charity he appears to take the possibility of anony-mous donations as something that would pose a problemfor his theory (Miller, 2000, p. 323). Miller in fact goesso far as to argue that people do not give anonymously.Instead he claims (and a very similar point is made byAmotz and Avishag Zahavi) that the social circle of socalled ‘anonymous’ donors will almost certainly knowabout the donation—and these are the people who matteras far as displaying your qualities are concerned as it is thisgroup that contains the actor’s potential sexual partners(Zahavi & Zahavi, 1997, p. 227; Miller, 2000, p. 323).Whatever the merits of this proposal it leads us onto thesecond problem facing the sexual selection account: thatwhat is produced by sexual selection may not be psycholog-ical altruism at all.

If we are genuinely motivated by the interests of others,it appears that when we want to help them we want to doso for their sake—not as a means to further our own ends.Examples of such desires would be wanting someone’s pain

6 In one of these experiments subjects were told that they would be involved inTo avoid embarrassment each person would be in a separate cubicle and commthat everyone could speak twice and then there would be a group discussion.experimenters) revealed that they were prone to seizures, and on their next turnfor the subjects to leave their cubicle and seek help for the victim. 85% of thoseof those who thought that four other people knew of it did so. For further de

to end, and wanting your friends to prosper—where theseare wanted for their own sake. There seems to be no reasonfor thinking that people with such desires will not help attimes when no-one will know that they have done so. Thus,it appears that a species capable of psychological altruismwould be perfectly capable of helping in ways that areanonymous. As a result, if sexual selection accounts ofthe evolution of helping behaviour rule out anonymousdonations, this would suggest that what sexual selectionproduces is not psychological altruism after all.

Indeed, systems that produce desires to help others fortheir own sake seem to be singularly ill equipped to producethe sorts of helping behaviour that sexual selection wouldfavour. Suppose that, on becoming aware that you are inpain, I come to want that pain to end. It appears that thesorts of information I will make use of when deciding whatto do in this situation are things like: how much pain youare in, what help I can give you, how effective that help willbe in relieving your pain, and the cost of helping (at least interms of what else I would need to give up were I to help youin one way or another). That is, the processes that lead up tomy helping behaviour do not seem to take any account ofthe visibility of helping you, but they do take account ofwhat will actually benefit you most. This is not what wewould predict a sexually selected helping mechanism wouldlook like—such a system would take account of the visibil-ity of helping, but not of the effectiveness of doing so.

While it is true that if I am motivated to help others fortheir own sake I may well take the costs of helping intoaccount, as the sexual selection account suggests I will,even here I will not do so in the right way. If what moti-vates me is your need, I will try to help you in the most effi-cient way possible—doing so reduces the cost to me, whileensuring that you get the benefits that I want you to have.But, mechanisms selected for by sexual selection will notwork in this way. Such mechanisms are in the business ofproducing a display, and the most effective way to meetyour need may well not be the best way to display my attri-butes. This is a point that Miller makes use of in his argu-ment that our behaviour in giving to charity is evidence forsexual selection of human helping. He claims that the factthat we often choose to help others by giving up our time todo ‘charity work’ reveals that we use generosity not as anefficient way to help those in need (to do that we wouldbe better off donating more money) but rather as a fitnessdisplay (Miller, 2000, p. 322).

If the purely altruistic motivational system describedhere does not produce the patterns of behaviour predictedby sexual selection accounts, it is not difficult to come upwith a system that does rather better in this respect. It

a discussion about personal problems with one, three or five other people.unicate by microphone. Each microphone would be switched on in turn soOn their first turn the future victim (actually an actor in league with theappeared to be having one. The experiment tested how long it would takewho thought that they alone knew of the seizure reported it, but only 31%tails of these experiments, see Latane & Darley (1970).


would be naı̈ve to think that every time we go to someone’said we are motivated to do so purely by their needs. Peopleare aware, at least on some occasions, that helping otherswill impress people and even that it will help to improvetheir own status—a point emphasised by Zahavi (2000, p.255). In such cases they may choose to help to achieveone of these ends. Similarly, where people anticipate beingblamed when they do not help, or being praised when theydo, we might expect that they will sometimes help as a wayto get praise and to avoid blame.7 Finally, where peopleselect partners at least partly on the basis of their displaysof generosity, we may simply have developed the ability totell what preferences the opposite sex have and the abilityto reason from ends to means. If we have, then we maydecide to act generously as a way to improve our chancesof attracting a particular sexual partner.

Such helping is not altruistic in the psychologicalsense—the people concerned are helping as a way to fur-ther their own interests. But, if some of our helping is moti-vated in these ways, then this would help to produce thepattern of helping behaviour predicted by sexual selectionaccounts. Where we are helping to impress people, or toreceive praise, we are only likely to help where we thinkour helping will be visible to others. As such, these self-interested motives will tend to reinforce any altruisticmotives that we may have on those occasions where we willbe seen to have helped in a way that they will not wherehelping would be anonymous. This, in turn will increasethe chances that we will actually help on those occasions.Similarly, these self-interested motives may be best servedby helping in extravagant ways, thus making it more likelythat we will engage in the costly helping predicted by sexualselection accounts.

It appears, then, that motivational systems that containboth altruistic and non-altruistic motives will produce thepattern of behaviour that sexual selection would predictin a way that purely altruistic motivational systems willnot. They do so because non-altruistic motives for helpingseem to produce the sorts of behaviour that sexual selectionwould tend to favour. Because of this, where we find thepattern of helping behaviour that sexual selection appearsto predict, as Miller claims to have done in relation toour charitable donations, this cannot easily be seen as evi-dence for the sexual selection of psychological altruism.What produces that pattern are the self-interested elementsof our motivational system. As such, far from being evi-dence for psychological altruism it may appear that thisis actually evidence that at least some of our motives forhelping are not altruistic, but self-interested.

Mixed systems of the sort just described are still capableof psychological altruism. As a result, they are still ones thatare quite capable of producing helping that is anonymous,even if it turns out to be less common than helping where

7 This is a possibility that John Darley and Bibb Latane raise in their discbasically is that where more people could help responsibility, and hence praise abe blamed for failing to help to the same extent when other people could hav

we will get recognition for doing so. Thus, if this is what sex-ual selection has produced there is still no reason for think-ing that it rules out anonymous donations, and no need toexplain such donations away (as Miller and Zahavi attemptto do). But, if sexual selection would tend to favour non-altruistic motivation, then it seems that it would also tendto remove any motivation to help that is altruistic in thepsychological sense. In that case, Miller would be right tothink that anonymous donations would threaten his sexualselection account. As we have seen purely altruistic motiva-tional systems do a poor job at producing the sorts ofbehaviour that sexual selection predicts. Although mixedmotivational systems do a rather better job, they continueto produce desires to help where there are no benefits interms of attracting potential mates—for example, by pro-ducing desires to help where no-one will know that you havehelped, and by producing desires to help in the way that bestmeets the needs of the other person rather than that whichbest displays our personal qualities. Purely non-altruisticmotivational systems would not do this. As such, we mightexpect that such motivational systems might do even betterthan those which contain both altruistic and self-interesteddesires to help others when it comes to producing behaviourthat is attractive to potential mates.

Of course, things might not work out that way. In somecircumstances, psychological altruism may be the bestoption available for producing sexually attractive behav-iour. It may also be that helping others provides benefitsin addition to those connected with sexual success. But,given that we have powerful self-interested reasons for help-ing others, there is reason to think that the tendency will befor sexual selection pressures to have strengthened thosemotives at the expense of any purely altruistic motives thatwe may have. Because of this it appears that sexual selectionaccounts of human helping behaviour are not well suited forexplaining the evolution of psychological altruism after all.Just as the behavioural evidence produced in their favourseems to be evidence for the non-altruistic elements of ourmotivational systems, it appears that the tendency will befor sexual selection to favour those non-altruistic mecha-nisms at the expense of altruistic ones. That way the result-ing motivational system will be the one that is most likely tolead to us helping where there are benefits in doing so (interms of impressing the opposite sex) while not wastingresources where helping produces no such benefit.

4. Response: a module shaped by sexual selection

In everything that has been said so far we have, I think,been tacitly accepting what is perhaps the standard pictureof desire formation. According to this picture—which fol-lowing Robert Audi we can call motivational foundational-ism—there are some things that we want for their own sake

ussion of the bystander effect (Darley & Latane, 1968, p. 378). The ideand blame, are diffused through the group. As a result, we do not expect to

e helped, as when we alone could do so.


(which we can call ‘basic’ desires), and everything else thatwe want we want as a way to help us to satisfy our basicdesires (Audi, 1989, p. 36). There is a tendency to reducethe number of things that we want for their own sake toas small a group as possible. For instance, according toRobert Noggle, ‘The most plausible version of [motiva-tional foundationalism] holds that biological forces suchas drives and homeostatic mechanisms produce or consti-tute basic desires that can then combine with beliefs andproduce non-basic desires . . .’ (Noggle, 1995, p. 59). Onthis account, then, we have basic desires for things likefood, drink, sex, warmth, pleasure and pain. Every otherdesire is produced from these basic desires by means—end reasoning. An even more restricted set of basic desiresis posited by psychological hedonism, which at least onElliott Sober’s characterisation of it, claims that our onlybasic desires are desires for personal pleasure and desiresto avoid personal pain (Sober, 1992, p. 101).

I suspect that it is this tendency that creates the prob-lems for sexual selection accounts of psychological altruismthat we have been looking at. For example, as we saw ear-lier, Miller’s evidence suggests that our desires to help arenot basic. If we wanted to help others for its own sake, thenit is hard to see why it is being seen to help rather thanactually helping that plays the most important role in get-ting us to act. His evidence suggests, rather, that we arehelping as a way of satisfying some other desire—forinstance, the desire for sex or for improved status. But, ifthis is why we want to help, then our helping behaviouris not altruistic in the psychological sense. We are beingmotivated by our own interests rather than the interestsof others. What I want to suggest is that the tendency tosee basic desires as some minimal set based on biologicaldrives and homeostatic mechanisms should be resisted.Instead we should see our basic desires as the outputs ofsome form of desire forming modules.

4.1. Desire forming modules

To start with, the idea that we have a small set of basicdesires and all of our other desires are present as a way tosatisfy those in that set seems to be problematic when weconsider what R. Jay Wallace calls the ‘unruliness’ of manyof our desires. By describing desires as unruly Wallace isreferring to, ‘the fact that many desires are not responsiveto our practical reasoning about how we ought to act’

8 It might be thought that these are simply cases where we have ends that arwants to stop smoking as a way to ensure her future health. Unfortunately shethat there are ways to get pleasure other than by smoking, ways that are compremains, ‘why does she want to smoke as a way to get pleasure, where she knothat do not conflict with those aims?’

9 In a different context Kim Sterelny has made much the same point about10 This is not to say, however, that we would need a different system for each d

to produce desires for those things that have given us pleasure in the past, wheproduce desires to eat cake (when we can see cake) and desires to smoke (whenencapsulated because it can only make use of information about what has givinformation that is relevant to what we want to do would be unavailable to i

(Wallace, 1999, p. 640). For example, consider Anne whohas decided that all things considered she wants to stopsmoking. The damage to her health and her wallet, she rea-sons, are too high a price to pay for the benefits she getsfrom smoking. This does not mean that Anne will neverwant to smoke, even if she continues to judge that notsmoking is preferable to her. It is a common occurrenceamong ex-smokers that they experience repeated, althoughnot continuous, cravings for a cigarette. Occurrences of thistype are not restricted to those who are coming off drugs—Imay have judged that all things considered I will not havedessert after my meal, for example, but when the waiterbrings across the sweet trolley I experience a strong desireto have one. In both these cases the agent may, of course,withstand the temptation to consume. But the importantpoint here is that desire forming seems to be unruly, it doesnot take account of our judgements, nor of all our beliefs.8

For a different type of example that illustrates the samepoint, consider food aversions. It appears that whatever thesystem is that produces our desires for food, they will notproduce desires to eat certain substances even if we arehungry. Instead we will shy away from these potentialsources of food. For instance, when we have been nauseousafter eating a particular substance we may come to have anaversion to it. This is usually a reasonable thing to happen,things that make us nauseous are likely to be dangerous.But it seems that we will retain the aversion even if wedo not believe that it was the food that made us ill. Thisis a surprisingly common event. When A. W. Logue andcolleagues carried out a survey on food aversions inhumans they found that 21% of respondents said that theythought the cause of their illness was something other thanthe food they became aversive to (Logue et al., 1981, p.326). But if people believe that a particular food is not whatmade them ill, why do they not want to eat it? Particularlyif, as is often the case, they previously liked that type offood. Here again it looks as if our desire forming systemsdo not take into account all the information available tous. And again this seems to be a widespread occurrence.

What examples like these suggest is that the systems thatproduce at least some of our desires do not have access toall the information that is available to us.9 That is, they are,to use Jerry Fodor’s term, ‘informationally encapsulated’(Fodor, 1983, pp. 64–86). The examples also suggest thatour desires are not all being produced by the same sys-tem.10 To see why let us go back to the example of Anne

e incompatible—Anne wants to smoke as a way to get pleasure, say, andcannot get both. But this would be a mistake. Anne may be perfectly awareatible with her desire for a long and healthy life. Given that, the questionws this conflicts with her other aims, when she could get pleasure in ways

our food aversions (see Sterelny, 2003, p. 84).esire, or even for each ‘unruly’ desire. For instance, a system that was set upnever we are in the presence of cues that those things are available, couldwe are in a smoky atmosphere). Such a system will still be informationallyen pleasure in the past, and cues about our present situation. Any other

t.


who is trying to stop smoking. It seems that when Anne hasa desire for a cigarette, the system that produces that desiredoes not have access to information about her decision tostop smoking on health grounds. But, notice that Annehas other desires that conflict with her desire for a cigarette,and the processes that form these desires do appear to haveaccess to that information. Anne’s desire to go to the shopto buy nicotine patches is one such desire. It seems that it isonly if she believes that this is a way to implement her deci-sion to stop smoking (itself a way to satisfy her desire for alonger and healthier life) that she will come to have thatdesire. So, the system that produces Anne’s desire for a cig-arette is informationally encapsulated in a way that the sys-tem that produces her desire to go to the shop to get somenicotine patches is not. The former does not have access toall the information that the latter does. This suggests thatthey are different systems. You can tell a very similar storyabout the desires to eat of the dieter, and of the person witha food aversion, described above. In each case the systemsthat produce one of their desires (to eat the cake, or avoidthe particular type of food respectively) does not appear tohave access to information that is available to other of theirdesire forming systems. Thus, they appear to be separatesystems.

The picture of our desire forming system that these sortsof consideration suggest is one in which there are a range ofspecial purpose desire forming systems each of which islimited in different ways, and which produces desires onlyof a particular type. It seems reasonable to call these sys-tems ‘desire-forming modules’ given Fodor’s claim that,‘The informational encapsulation of the input systems is. . . the essence of their modularity’ (Fodor, 1983, p. 71).Although not all proponents of modularity agree thatinformational encapsulation is needed for modularity—Simon Baron-Cohen, for instance, denies that the ‘mind-reading’ modules he proposes are informationally encapsu-lated (for a discussion of this point see Samuels, 2000, p.20)—it does not appear that they would deny that systemswhich are informationally encapsulated are modular insome sense.

Before continuing two important points need to bemade. The first is that the idea that there are desire formingmodules does not preclude the possibility that many of ourdesires are not produced by such modules. When Fodorfirst introduced the idea of modularity he restricted mod-ules to input systems, leaving the rest of the mind as non-modular. Something similar could well be the case fordesire forming modules—that is, there could be a set ofmodules that produce some of our desires and these pro-vide inputs to some non-modular system. In such a systemthe outputs of desire forming modules would, like the basicdesires described earlier, be things that we can work outhow to satisfy using means—end reasoning. The secondpoint is that, again like Fodor’s input systems, there maywell be a range of modules producing desires connectedwith one domain or area of activity. We do not have amodule that produces beliefs about how the world appears

to us, rather a range of different modules produce suchbeliefs even within a particular sense modality. Similarly,there need not be just one module that produces desiresconnected to food, say, or desires for those things that willattract sexual partners.

4.2. An ‘altruism module’

Suppose that this is correct and our minds do containmodular desire forming systems, and further suppose thatthese modules have been shaped by selection pressures toproduce desires for things that we need to do to surviveand reproduce. How would this help those who wish todefend a sexual selection account of psychological altruismagainst the criticisms raised earlier?

As we have seen sexual selection accounts focus on theneed to act in ways that will attract potential mates. Help-ing others is one way in which we might do this. As such, amodule that regularly produces desires to help (what I willrefer to as an ‘altruism module’) could well, all else beingequal, be favoured by sexual selection. It will make it morelikely that we help those in need, and helping those in needincreases our chances of attracting sexual partners. Impor-tantly, however, it is not just the existence of an altruismmodule that may benefit us in the competition for sexualsuccess. The internal workings of such a module, the algo-rithm that it runs to produce the desire to help, may alsovary from person to person. Some of these algorithms willdo a better job than others at producing desires to act inways that attract the opposite sex. Thus, sexual selectionwill tend to favour some versions of the altruism moduleover others. To see how this could happen, let us focuson helping as a fitness indicator.

If the system that produces our desires to help is analtruism module that has evolved as a fitness indicator,then its only task will be to produce desires to help thatindicate fitness. The versions of this module that wouldbe favoured by sexual selection are those that make it mostlikely that we will help in ways, and at times, where ourhelping serves as a good demonstration of our fitness—these will be those that take account of the visibility ofany help that we provide, and its effectiveness at displayingour fitness. An example of the sort of system that could befavoured in this way is one which is set up as follows. First,systems outside the module provide a filter so that it is onlytriggered when you are in a position where you can help.Second, on being triggered the module assesses the helprequired, whether others can help and whether anyone willknow that you have helped. This is the information thatseems to be relevant when assessing whether or not helpingwill demonstrate your fitness. In general, if no-one elsecould help, then, as long as people know you have helped,helping will be a very good indicator of fitness. So, rescuingsomeone from a burning building will be a good indicatorof fitness because most people do not have the courage orresourcefulness to do it. On the other hand, giving a smallamount to charity is something that most other people


could do and, as such, it will not provide much informationabout an individual’s fitness compared to other people.Third, on the basis of this assessment the module producesa desire to help whenever you can help and it will be knownthat you have helped. Finally, it adjusts the strength of thatdesire so that it is stronger where helping is something fewother people could do, and weaker where it is somethingmany other people could do.

The first thing to note about a desire forming systemcontaining a module along these lines is that, althoughthe altruism module has been shaped by sexual selection,it does not predict that we will be more likely to help wherethere are more people around to witness us doing so. Thisis partly because the presence of more people may weakenour desire to help, in that case we are more likely to judgethat others could help as well as we could and so helping isnot a particularly good indicator of our fitness. But it isalso partly because the altruism module does not produceall of our desires. We will want other things too, and thesemay well come into conflict with our desire to help whenwitnesses are present. Thus, sexual selection accounts ofthis type are quite consistent with the bystander effect.

Competition between desires also allows a way toaccount for self-sacrificial helping. According to sexualselection accounts the extent to which we help should besensitive to whether or not we can afford to help, butself-sacrificial helping appears to show that it is not. How-ever, a modular desire forming system can be sensitive tothe costs of helping even if the individual desire formingmodules take no account of the consequences of actingon the desires they produce. It can do so because eachdesire has to compete against the desires produced by othermodules. For instance, whether we can afford to act on anyparticular desire to help will depend on the other thingsthat helping will rule out. Because of this there is no needfor the altruism module to take account of the costs ofhelping. Thus, it could produce a self-sacrificial desire, suchas the desire to help by throwing yourself on a grenade.This will be one of the desires we could choose to act on.Almost always, however, we will not do so. Thus, if ourdesire forming systems are like this we will be capable ofacts of self-sacrifice, but such acts will be rare. This fits withwhat we know of human behaviour.

4.3. The behaviour that results is altruistic in the

psychological sense

We have seen how a desire forming system that includesan altruism module shaped by sexual selection could pro-duce self-sacrificial behaviour and is consistent with thebystander effect. As such, it seems that sexual selectionaccounts can respond to the first of the two problems thatwe encountered earlier. More importantly, perhaps, theidea that our desire forming system is modular also appearsto provide a way to respond to the second of those prob-lems. Recall that the problem here was that desires to helpothers for their own sake do not seem to be the sorts of

thing that sexual selection would favour. Rather, to obtainthe best results in terms of attracting the opposite sex, whatwe seemed to need were non-altruistic motives for helpingthose in need. That is, it appeared that the motivationalsystems favoured by sexual selection would not be onesthat produced psychological altruism.

By introducing the idea that the desire to help others isproduced by a module, however, we have opened up away in which the pattern of our helping behaviour canbe such that it is well adapted for attracting the oppositesex without needing to introduce non-altruistic motivesfor helping others (although this is not to say that suchmotives do not exist). If our minds contain such a module,then sexual selection can affect the internal workings ofthe module itself rather than having to add new desiresin order to get the right pattern of helping behaviour.As a result, if our minds contain such a module, the waysin which we want to help those in need, and the strengthof our desires, will vary depending on the situation we arein. What is more, they will vary in ways that tend to makeit more likely that our helping behaviour will make usmore attractive to potential mates. Nevertheless, if weact on those desires it would appear that our motive inacting is not our own interest but rather the interests ofsomeone else.

In order to see this we first need to draw a distinctionbetween two types of explanation that we might give ofhuman motivation: those that focus on how we came tohave the motivational systems that we have, and those thatfocus on what our ends are in acting as we do (for furtherdiscussion of this distinction see Kavka, 1986, p. 63; Sober& Wilson, 1998, pp. 199–200). The account that we havebeen looking at—of how an altruism module could be pro-duced, and shaped, by sexual selection—is of the first type.It tells us how we came to have the systems that producecertain desires. At this level, it is true that what I have beencalling an ‘altruism module’ produces a desire to help onlywhere doing so is visible to others. And, it is also true thatthis is no accident: the module has been shaped to do justthat because having such desires increased the chances thatour ancestors would act in ways that attracted potentialmates. So, in some sense, we have desires to help onlybecause doing so benefits us (or at least benefits our genes).

It is important to see, however, that this does notdirectly tell us anything about what our motive is in helpingor about what we are aiming to achieve by acting as we do.This is not to say that in other cases it would not do this. Ifthe account of how we come to have the motivational sys-tem that we do operated as the sexual selection accountappeared to (see Section 3), then the resulting system wouldbe one in which the details of how the motivational systemevolved revealed our motivation for helping—the systemproduces only a few basic desires which are all self-inter-ested, and as such the only type of motivation it can pro-duce is one that is non-altruistic (at least in thepsychological sense). On such an account, as we have seen,one way to get us to help is to ensure that individuals have


a preference for generous and helpful mates, and that wecan tell that about each other. We will then want to helpas a way to further our own ends. This was the source ofthe worry identified earlier—if this is what is happeningthen our helping is not altruistic in the psychological senseat all. But, once we move to a system in which basic desiresare not all produced directly by evolution, and under whichsome are produced by modules, then this need not be whatis going on. Indeed, if our desires to help are produced by asystem like the one described here, it is not what is goingon. Although the altruism module has been produced toget us to act in ways that impress others, increase our statusor attract sexual partners, it will produce a desire to helpwhether or not we want any of these things. The modulewill fire, in other words, irrespective of what we want. Itdoes so automatically, producing a desire to help whichwe may find intrusive and which we would far rather nothave. This is surely a common feature of our experience.If we act on such a desire, it would seem that we are notmotivated by our own interests—after all, we do not thinkthat it will promote any of our own interests. Thus, suchaction looks to be altruistic in the psychological sense.

5. Conclusion

It seems, therefore, that whereas sexual selectionaccounts of the evolution of psychological altruism appearproblematic if our minds are non-modular, things are verydifferent if the systems which produce our desires containmodules. In that case motivational systems that would pro-duce altruistic motivation are just the sorts of things thatcould be sexually selected for. That our desires to helpare, at least partly, produced by such mechanisms wouldalso fit with much of our observed helping behaviour. Thisis not to say that we are in fact capable of genuine psycho-logical altruism, nor that, if we are, the capacity to do sowas produced by sexual selection. It is possible that thereis a better explanation of our behaviour. However, it does

show that the capacity for psychological altruism inhumans could have been produced by sexual selection,and it is this that was my aim here.

Of course, an altruism module that is as simple as theone I have described above could not account for the fullrange and complexity of our dispositions to help. Forone thing, any actual altruism module would undoubtedlybe much more complex than the one I have briefly sketchedhere. For another, there is no reason to think that, even ifwe have an altruism module, it would produce all ourdesires to help. It is possible that other desire forming mod-ules, such as modules that produce desires to get pleasureor to avoid pain, could also do this. If desire forming ismodular, we would expect there to be modules which pro-duce desires of this type because in general pain appears to

11 This is not meant to be anything like a full account of our helping behaviourillustration of how it would be possible to produce a desire to help from a ple

be produced by things that are detrimental to an individ-ual’s fitness, and pleasure by things that are beneficial totheir fitness (at least until fairly recently). Such modulescould produce desires to help in an individual who grewup in an environment where they learn that helping otherstends to lead to pleasure and not helping tends to lead topain. For example, they may have been rewarded whenthey helped, and punished when they did not.11 Such anindividual has a mental module which will produce desiresfor those things which tend to lead to pleasure, and haslearnt that helping others tends to lead to pleasure. Becausethe module is informationally encapsulated there is no rea-son to think that it will also have access to any informationthe individual may have about whether or not helping inthis instance will lead to pleasure or will reduce the chancesof experiencing pain. As such, they may well come to wantto help even where they believe that helping will not lead toany pleasure or avoid any pain. Of course, the individualmay not act on this desire. Other interests may get in theway. But, because of the environment they have grownup in, they are capable of forming a desire help otherswhere there is no benefit to themselves.

Acknowledgements

I would like to thank Stephen Laurence, Richard Joyce,David Owens and an anonymous reviewer for helpful com-ments on earlier drafts of this paper, and the Arts andHumanities Research Board for financial support. Versionsof this paper have been presented to audiences in Sheffield,Belfast and Canterbury and I am grateful to all those whoparticipated in the discussion on those occasions for theircomments and questions.

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