Stone Age Minds
and
Group Selection –
What difference do they make?
Jack Vromen
EIPE
[email protected]
(first draft; please do not quote)
Paper prepared for the Workshop ‘The Nature and Evolution of Institutions’,
Jena, 11-13 January 2001
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1. Introduction
Over the last years evolutionary psychology (EP) and Sober and Wilson’s
multiselection theory (MST) attracted much attention. These two currents in
evolutionary theorising did not only gather adherents. Both currents provoked
massive and sometimes heated controversy. But they succeeded in establishing
themselves as ‘centres of gravitation’ pulling together much of present-day debate
within evolutionary theory. Evolutionary psychology and multiselection theory also
caught the eye of practitioners in the social sciences. There also they are received in
many different ways. Not only range responses from utterly dismissive all over to
wholeheartedly affirmative. There also seem to be much confusion about what
evolutionary psychology and multiselection theory are and what they could mean
for the social sciences.
This paper sets out to do three things. First an attempt is made to understand the
basic ideas in both theories. This already is not an easy task. This is so for several
reasons. Both EP and MST are relatively recent endeavours. They both are ‘moving
targets’ that are still in their infancy. Their basic claims and ideas are often also
ambiguous, as we shall see. And in EP there seem to be internal disagreements. The
second thing I want to do is to compare the two theories with each other. Significant
agreements and disagreements between the two will be spelled in some detail. And
finally some first steps are made to find out of what possible relevance EP and MST
are for economics.
2. Evolutionary psychology (EP)
Evolutionary psychology (EP) often is depicted as sociobiology in disguise (or
1
sociobiology garbed in a new dress). Edward O. Wilson, for example, one of the
founders of sociobiology (Wilson 1975), argues as if EP is identical to sociobiology
(Wilson 1998, 165 and 185). But this, I think, slides over at least one significant
difference between the two. Sociobiology has often been said to endorse genetic
determinism. Sociobiology holds, it is argued, that genes code for brain archtecture
and brain processes, and that these in turn would directly determine behaviour. EP
differs from sociobiology in that much more attention is paid to an intermediate link
in between neurophysiological processes and brain architecture on the one hand, and
behaviour on the other. Indeed, EP has been introduced by its pioneers as an attempt
to provide the missing link in evolutionary theory (Cosmides and Tooby, 1987). EP
situates this link at the level of the human mind. To be more precise, EP postulates
the existence of a multitude of psychological mechanisms (or modules) working at
the level of the human mind (Buss, 1995 and 1999).
In order to fully comprehend EP, the crucial distinction between ultimate and
proximate causes has to be well understood. Indeed, it is no exaggeration to state that
the whole of current evolutionary theory cannot be understood if this distinction is
disregarded (see, for example, De Waal, 1996). The distinction goes back to Mayr
(1961). Mayr argues that there are several perfectly legitimate answers to the
question why for example warblers migrate to the south when winter is about to
1
It has to be noted that EP is far from uncontroversial. There also seem to be different views within
EP. And central notions do not seem to be unambiguously defined. For more on this, see Vromen
(1999a).
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come. What is the cause of bird migration? One legitimate answer is that migration is
linked with photoperiodicity. Warblers are equipped with some internal
physiological machinery that allows them to sense decreases in day length and that
allows them to respond by migrating southwards. Another legitimate answer is that
during the evolutionary history of the species, warblers have gained a genetic
constitution making for such internal physiological machinery. Here the causes are
the evolutionary forces that impinged on the ancestors of the warblers living now.
Mayr calls the first class of causes proximate causes and the second class ultimate
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causes.
Proximate causes refer to the decision-making machinery (or behaviour-instigating
mechanisms) inside the behaving entity. They are internal to the behaving entity and
they operate just before the behaviour is displayed. Ultimate causes on the other
hand refer to circumstances outside ancestors of the behaving entity responsible for
the behavioural profile the behaving entity has now. Thus, while proximate causes
refer to causes internal to the behaving entity working now, ultimate causes refer to
causes that were external to its ancestors then (that is, to causes working way back in
time). The link between the two types of causes is that proximate causes are effects of
ultimate causes. Ultimate causes impinging on behavioural entities in the past have
produced the proximate causes that govern the behaviour of their descendants now.
One of the central (if not the central) ultimate causes in evolutionary theory is natural
selection. But what are the paradigmatic species of proximate causes in evolutionary
theory? The example of the migrating warblers given above suggests that
neurophysiological processes inside organisms are prime proximate causes in
evolutionary theory. If we add to this the widespread belief that neurophysiological
processes are coded for in the organism’s genes, then the image that emerges is one
of a direct, straightforward chain running from genes over neurophysiological
processes to overt behaviour. It seems we are back then at genetic determinism.
Agency appears to have vanished from the evolutionary scene. Not we ourselves are
in charge of what we do. It is our genes that, via the neurophysiological processes
that they code for, determine our behaviour.
But this need not be the case. EP identifies psychological mechanisms (or modules) at
the level of the human mind as the proximate causes of human behaviour. And
although genes undoubtedly play an important role in the construction of
psychological mechanisms, their workings need not be (and probably are not) fully
determined by them. Indeed, EP tries to be as neutral as possible on ontogenetic and
heritability issues (Symons 1992, 141).
What exactly are psychological mechanisms and with what psychological
mechanisms are we equipped according to EP? EP is often circumscribed as
'cognitive science meets evolutionary theory'.
From cognitive science (see
particularly Fodor, 1983) EP takes over the idea that the human mind consists of
modules. Typically, when confronted with some task not all of the human mind is
mobilised. Only one module, as a part of the mind, is activated. What part is
activated depends on the domain to which the task belongs. Now, what domains are
there and, relatedly, what modules does our mind consist of? Here evolutionary
2
Actually, Mayr discusses two more classes of causes. They too can be classified in terms of proximate
and ultimate causes. But for the purpose of this paper discussion of the two classes of causes mentioned
suffices.
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theory comes in. EP holds that in order to tell what modules we have and in what
domains they are triggered, we have to look at the evolutionary (sub) problems our
ancestors had to cope with. The idea here is that although it is clear that individual
differential reproductive success was decisive in the evolution of the human species,
our ancestors were never directly faced with the problem of how to maximise their
individual reproduction rate. What they were directly faced with instead was some
component of this. In order to achieve a favourable reproduction rate several
evolutionary subproblems had to be solved. Obviously, finding a suitable individual
of the opposite sex to mate with was such an evolutionary subproblem. And so are
successes in withstanding climatological changes, in staying away from predators
and in solving co-operation problems in groups. A central hypothesis in EP is that
domains correspond to such evolutionary (sub)problems and that our modules
evolved to solve these problems.
Perhaps the best worked out example of a module is the cheater-detection algorithm
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discussed by Cosmides and Tooby (1992). Cosmides and Tooby argue that in order
to have ‘TIT FOR TAT’ sustain a social contract, the people in question must be good
at spotting cheaters. If people were not good at this, they would be unable to punish
cheaters. And the latter of course is crucial to TIT FOR TAT. In Cosmides and
Tooby's opinion, the existence of a specialised cheater-detection algorithm is
confirmed by the findings in the Wason Selection Task. Peter Wason devised his
Selection Task to find out whether people perform well in applying modus tollens, the
logical rule underlying Popper's falsificationism. To his surprise, people tended to
perform quite poorly. The only exception to this tendency was when a specific type
of propositional content was given to the problem. When the problem was framed in
terms of a social contract problem, the performance rate increased dramatically from
less than 25% to 75%. Apparently, then, Cosmides and Tooby conclude, people avail
of a content-specific algorithm, an algorithm that is activated only if the problem has
the right propositional content.
EP advances a Swiss army knife model of mind on which the human mind consists of a
multitude of such special-problem devices. Each of these devices evolved to solve a
specific evolutionary (sub)problem in times long foregone, EP argues. But they can
still be triggered if people are provided with the right informational input. In this
sense, our skulls still house a stone-aged mind. EP revitalises the view that people all
around the world share the same basic repertoire of modules. Human nature is said
to be the same everywhere. But it is important to recognise that human nature, as EP
sees it, is not of a piece. What module is activated, to repeat, depends on the
informational input provided. This explains why the same people who behave
altruistically in some setting (as in following TIT FOR TAT in social contract settings)
behave much more self-regardingly in other contexts.
Do our modules prompt us to behave rationally? Among other things this depends
on how well adapted modules were to ancestral circumstances and to what extent
our present-day circumstances resemble these ancestral circumstances. Behaviour
that was optimal then may well be far from optimal now. The Maladapted Mind
(Baron-Cohen 1997), for example, discusses current psychopathologies as
adaptations to the Environment of Evolutionary Adaptedness (EEA) that in relevant
respects was rather different from environmental circumstances we are now
confronted with. Cosmides and Tooby (1994) advance the puzzling suggestion that
3
The most controversial example of a module no doubt concerns mate preference.
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behaviour prompted by our modules may make for better than rational behaviour.
What they mean by this is that having a rich repertoire of special problem-solving
devices (as EP claims) may be more efficient than having just one general problemsolving device. Modules as special problem-solving devices function as shortcuts,
facilitating 'fast-track' learning. Hence they save on time and energy. The flipside of
this is, however, that our stone-aged skull may be poorly adapted to solve today's
problems. Our modules may prevent us from quickly learning certain useful things.
Thus modules enable and facilitate. But they also inevitably constrain and confine
(what can be learned or done).
Criticism
Over the last years EP has been criticised from several vantagepoints. For example,
EP has been criticised for endorsing an extreme form of adaptationism. EP is said to
entertain the view that all enduring life forms are optimal solutions for problems
produced by natural selection. In the preceding paragraph I already touched upon
this issue. I believe this criticism is cogent only up to some point. EP abides to the
adaptationist program. But it does not take for granted that all features of our minds
are perfectly adapted to the EEA (let alone that all features are perfectly adapted to
our present circumstances). EP has also been criticised for embracing genetic
determinism. But although at least some EPists seem to be wedded to the view that
the ontogenetic development of our mind’s modules is genetically specified (in some
sense; see below), no one of them goes as far as to claim that this development is
fully genetically determined.
More reasonable critiques seem to come from those who criticise both the way
Cosmides and Tooby conducted Wason selection task experiments and the
conclusions they draw from them (see, for example, Evans and Chang 1998).
Contrary to what Cosmides argues, critics hold that it is not at all clear whether her
account of these experiments in terms of biologically evolved algorithms is superior
to what this was supposed to supersede: the permission and obligation schema
proposed by Cheng and Holyoak. In fact, some even fail to see a real difference
between the two accounts (Lloyd 1999, 221).
Several commentators argue that transmitted culture and cultural evolution in
general are given short thrift in EP. Although there may be some problems with
identifying exactly what (as an analogue of the gene) is transmitted in processes of
enculturation, there seems to be little doubt that ‘things’ like values, norms, customs,
conventions, notions, ideas and tunes spread and decline (in ways that differ from
genetic inheritance) in populations. ‘Evoked culture’, the notion EP introduces, may
fall short of capturing the most significant elements in processes of cultural
evolution. EP tends to explain cultural differences by referring to different ecological
circumstances evoking different behavioural responses from shared modules having
a conditional structure. Accounts in which more significance is allotted to
‘transmitted cultural evolution’ include Lumsden and Wilson (1981), Boyd and
Richerson (1985) and Durham (1991). More recently, in The Cultural Origins of Human
Cognition, Tomasello (1999) argues that some 250.000 years are too short for uniquely
human cognitive modules to have evolved in processes of biological evolution.
Tomasello argues that it is much more likely that in this relatively short period of
time (in terms of phylogenetic time) only one uniquely human biological adaptation
accrued: the capability of intentional and causal thinking. The capability of
intentional thinking includes the essential capability to understand others as
intentional agents (also having intentions, beliefs, plans and the like). It is this
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capability, Tomasello argues, that has allowed humans to obtain ratchet effects: the
maintenance of useful creative inventions. The problem with other primates is not so
much that they are much less creative than humans, but that newly invented
practices and artefacts are not faithfully transmitted socially so that slippages
backward occur time and again.
Buller (2000) contains what seems to be a sustained and well-informed criticism of
EP from the perspective of contemporary neuroscience. Buller introduces a useful
taxonomy of different claims made by EP, ranging from very general to specific ones.
At the most general level, EP’s claim that the human mind is the product of
evolution seems to be uncontested. At a somewhat less general level, EP’s claim that
our brain houses some specialised psychological mechanisms is not controversial
either. But in the light of contemporary neuroscience, Buller argues, EP’s claims that
go beyond this, its more specific claims, are questionable. Cosmides and Tooby’s
contention that the human mind consists of hundreds or thousands modules seems
to be unwarranted (see also Samuels 1999). And so are their claims that all of these
modules are uniquely human, stem from the Stone Age, and are universal and
uniform.
The most interesting point Buller makes, however, is that EP may well be right that
our brains produce specialised information-processing solutions to recurrent
evolutionary problems, but that they presumably got the way wrong in which the
brains produce the solutions. EP claims that adaptations are to be sought among the
products of brain development – that is, among the special-purpose brain structures
that emerge during the course of brain development. Recent research in neuroscience
suggests, however, that the fundamental adaptation rather is the brain’s
developmental plasticity. The relatively stable problem-specialised structures EP
posits emerge as by-products of interactions of the developmentally plastic brain
with particular environments. The picture emerging from this is that, contrary to
what EP claims, what is ‘innate’ is not a multitude of genetically specified modules,
but rather a relatively small number of learning biases in the brain that heighten the
responsiveness to certain classes of stimuli. A process of gradually branching domain
specificity, Buller argues, unfolds only later.
Buller’s discussion here no doubt is very informative. But one is left wondering how
damaging it is for EP. For if Buller is right, contemporary neuroscience agrees with
EP that in the end, after the brain has gone through a developmental process, many
special-purpose modules do come about (see also Cummins and Cummins 1999). It
seems that this vindicates one of EP’s central claims. Buller argues that the
developmental path leading to the emergence of the modules is quite unlike how EP
envisions it. But perhaps with the exception of a few proponents, EPists do not make
claims about what drives brain development. What is more, they are happy not to
burn their fingers on how brain and mind developments hang together. And,
furthermore, as we have seen in section 4, many EPists prefer to remain agnostic
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about hereditary and ontogenetic matters.
One last point of criticism is that our mind’s modules may not be informationally
rich (Mallon and Stich 2000). That is, they do may not provide us with clearly
4
On the other hand, it can be argued that closing their eyes for these issues and for developments
within adjacent disciplines deprives EPists not just of valuable sources of (possibly disconfirming)
evidence and information, but also of allying with possible bystanders. It seems, for example, that EP
can find some support in the neurosciences in the work of LeDoux, Gazzaniga and Damasio.
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specified biases and heuristics in our learning efforts. Knowledge of the modules we
have then falls far short of predicting how we will behave in various circumstances.
Environmental factors, social and natural, then can be argued to have a greater effect
on how we learn and behave. Sometimes EPists engage in some sort of
transcendental argument. They argue, for example, that every learning effort
requires, as some sort of a conditio sine qua non, innate capabilities that allow us to
learn. The logic behind this may be impeccable. But if the capabilities are
informationally poor, this need not tell us very much about how we actually learn.
3. Sober and Wilson’s Multi Selection Theory (MST)
In order to understand Multi Selection Theory (MST), let us first have a look at the
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notion of group selection. Group selection became a discredited notion for many
soon after Wynne-Edwards (1962) invoked the notion as an explanation of ultrasocial
behaviour in nature. There seem to have been two major reasons for this. The first
reason is empirical in kind. Starting with Williams (1966), many biologists (and
evolutionary theorists in general) have not so much doubted that 'group selection'
denotes a genuine possibility in nature, as that the conditions for the force of group
selection to be stronger than that of individual selection are so severe that they are
not likely to be met in reality. The second reason is conceptual in kind. Biologists
increasingly felt that, on the basis of Hamilton's (1964) inclusive fitness theory (based
on kin selection), and of Trivers' (1971) theory of reciprocal altruism, they could
explain all kinds of ultrasocial behaviour in what was regarded as orthodox
Darwinian terms of individual selection (or even in terms of gene selection; see
Dawkins, 1976). Hence there was no need for the notion of group selection.
Sober and Wilson (1998; see also Wilson and Sober, 1994) want to rehabilitate the
notion of group selection. In fact, Sober and Wilson want to establish at least two
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different points. The first is that the longstanding eschewal of group selection in
evolutionary biology is ill founded. Sober and Wilson want to rehabilitate the notion
of group selection. They argue in particular that if individual organisms are accepted
as paradigm cases of vehicles in evolutionary processes, as all evolutionary biologists
do, then there cannot be well founded reasons not to accept groups as vehicles also.
The second point Sober and Wilson want to make is that evolutionary altruism
requires group selection to evolve. Evolutionary altruism cannot possibly be the
outcome of individual selection. I will argue that in their attempt to establish the two
points Sober and Wilson put forward two notions of a group that are not only
different from one another, but that are even incompatible with one another.
First consider Sober and Wilson’s argument that evolutionary altruism requires
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group selection to evolve. As a starting point of their argument, Sober and Wilson
assume that individual selection is omnipresent and will inevitably lead (unless
counteracted by other evolutionary forces) to evolutionary selfishness. Sober and
Wilson define ‘evolutionary selfish behaviour’ as behaviour that enhances the
5
For a more detailed analysis and discussion of Sober and Wilson’s notion of group selection, see
Vromen, (1999b).
6
Another point Sober and Wilson want to establish in their book is that no fully compelling arguments
can be made for or against the existence of psychological altruism. In this paper I only deal with
evolutionary altruism.
7
The converse does not hold, however: group selection may also lead to non-altruistic, ‘nasty’
behaviour.
7
(inclusive) fitness of the behaving entity at the expense of the (inclusive) fitness of
other entities. Evolutionary altruistic behaviour is taken to be the opposite of this:
behaviour that enhances the (inclusive) fitness of others at the expense of one’s own
(inclusive) fitness. The argument here is the familiar one (familiar, that is, in
evolutionary theory) that no matter how well (evolutionary) altruists are represented
in a population, and how beneficial this is for all the individuals in that population
(in terms of their individual inclusive fitness), altruists will always be at an
evolutionary disadvantage compared to selfish individuals. For selfish individuals
will engage in free loading or free riding. They will ruthlessly exploit the selfsacrificing behaviour displayed by altruists. Altruists cannot withstand treachery or
mutiny from within. That is why in every population individual selection, if it is the
only evolutionary force at work, will eventually wipe out altruists.
Thus it takes some other evolutionary force (or forces) to prevent this from
happening. Sober and Wilson argue that group selection exactly is this evolutionary
force. Sober and Wilson carefully hedge this claim, however. When individual
selection does not act alone, but is joined with group selection, altruism can survive.
This is not to say, Sober and Wilson hasten to add, that individual selection is always
accompanied by group selection. Group selection is not (or at least need not be) as
omnipresent as individual selection. Furthermore, if there is group selection, it may
not be strong enough to counter the altruism-eroding effects of individual selection.
What will happen depends on the relative strengths of the two evolutionary forces.
And, finally, even if group selection is powerful enough to overrule individual
selection, altruism may still not evolve. Group selection can also generate other types
of evolutionary behaviour than altruism. In sum, Sober and Wilson claim that group
selection is a necessary, but not a sufficient condition for altruism to evolve.
Now what exactly is group selection here? How does it work? And how can altruists
survive as a consequence of it? The key idea here is temporal isolation of interaction
clusters. If the individuals in a population have an equal chance of interacting with
one another, the eventual demise of altruism cannot be avoided. But if a population
is structured into groups of individuals only interacting with one another (with
respect to the evolution of some trait), then altruists have better prospects. To
simplify maters, say a population consists of two such groups, one consisting only of
altruists and the other consisting only of selfish individuals. Now if the individuals
in the groups only interact with other individuals in the same group for a while, the
first ‘altruist’ group will do better (in the sense of all its members leaving more
offspring) than the second ‘selfish’ group. As a consequence, the first group’s share
in the population will grow at the expense of the second group’s share.
It may appear that this already is enough to make Sober and Wilson’s point. After all,
it seems that if the process just described goes on long enough, the second groups’
share in the population will eventually be reduced to nil. But this is not the case. And
Sober and Wilson acknowledge it is not. For we should not forget to take individual
selection into account also. No matter how successful the first group is, it cannot
resist invasion of selfish mutants. Sooner or later a selfish mutant will make its
appearance in the group, exploiting the altruists. Selfish individuals can have no
better soil to thrive on than a group of altruists. So the share of selfish individuals
within the group will rapidly increase at the expense of the altruists. This will go on
until the share of altruists within the group has fallen down to nil. Since this will
happen in all groups, the inevitable outcome still seems to be that in the end we will
be left with only selfish individuals in the population.
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Sober and Wilson argue that what is needed next to temporary isolations of groups
are re-assortments of groups now and then. Only if altruists in different groups
occasionally ‘join forces’ (that is, form new groups) can the eroding consequences of
individual selection be compensated for. In sum, as Sober and Wilson see it two
things are both needed to thwart the eroding effects of individual selection:
temporary isolation of groups and periodic re-shufflings of groups (resulting in the
formation of new groups). These two things should suitably alternate in temporal
sequences in order to forestall elimination of altruists in the larger population.
The notion of a group involved here is a very minimal (or thin) one. A group is
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defined here solely in terms of interactions. It is enough for some individuals to
interact only with each other for some period of time to call them members of the
same group. Indeed, as other commentators also have noted (see, for example,
Maynard Smith 1998), Sober and Wilson are prepared even to call two individuals
that interact only once a group! What is more, the individuals interacting need not
have anything in common with one another except that they interact with one
another. Individuals can be radically different from one another in all respects, as
long as they for whatever reason only interact with each other they are part of the
same group. Let us henceforth call this minimal notion of a group the interaction
notion of a group.
This is not the only notion of a group Sober and Wilson entertain. In the argument
they develop to establish their other point – that groups can be vehicles just as
individual organisms– they invoke a different notion. This can be called the shared
fate notion. The key idea here is that the evolutionary fate of individual group
members can be as dependent of the evolutionary fate of the group they are part of
as the fate of genes is dependent of the individual organisms they inhabit. The
individuals in a group are ‘in the same boat’. They are integrated so tightly and tied
together so strongly in a group that when the group expires in competition with
other groups its individual members go with it.
At first it may seem that the unity of a group cannot be as tight as that of an
individual organism. After all, it seems that, contrary to genes within an organism,
individuals within groups can go their own way and can act against the interests of
the group as a whole. Sober and Wilson argue that sometimes the bonds between
individuals in a group are so strong that the individuals can be regarded as
inseparable parts of a comprising unit. More importantly, the above comparison
between genes within an organism and individuals within a group falsely assumes
that there is some sort of self-evident harmony between genes and the organism
housing them. From an evolutionary perspective the harmony between genes and
the organism (if there is one) is itself an adaptation. Far from taking this for granted,
evolutionary theory seeks to explain the internal integration and co-ordination of an
individual organism as a solution to the problem of how to cope with freeloading
selfish genes in the organism. Thus the internal integration and co-ordination of
individuals in groups is no less natural or elementary than that of genes within a
well-functioning organism. Both can be regarded as adaptations.
8
To be fair, Sober and Wilson also demand that interactions should have different fitness consequences
with respect to some trait. But I think that taking this additional requirement into account does not
affect our discussion here.
9
The latter is granted by proponents of the Dawkins’s ‘selfish gene’ perspective. Yet,
Sober and Wilson rightly observe, the selfish gene proponents accept individual
organisms as paradigm instances of vehicles in evolutionary theory. Sober and
Wilson argue that selfish gene adepts are bereft of a sound argument to refuse
accepting groups as vehicles also. The selfish gene adepts inist that what ulimately
counts in evolution is the relative success of repicators to propagate themselves in a
population. Sober and Wilson agree. But this does not establish that there can only be
individual selection. In arguing this selfish gene adepts commit the averaging fallacy:
by (rightly) insisting that the effects of selection always are to be counted in terms of
frequencies of replicators in some population they (wrongly) brush genuine
differences in causes under the carpet. A change in frequencies of replicators registers
the average effect of possibly different evolutionary forces. Such a change may be
caused by individual selection working alone, for example, or by the joint operation
of individual and group selection. This shows that Sober and Wilson believe the
group selection debate is about vehicles, not replicators. They also urge evolutionary
theorists to distinguish carefully between theoretical perspectives and actual causal
processes. They furthermore argue that evolutionary theory, unlike the selfish gene
perspective, should respect and reflect differences in processes. Their own Multilevel
Selection Theory (MST) purports to be exactly that: an attempt to clearly bring out
differences in processes in evolutionary theory.
As indicated above already, the notion of group selection associated with the shared
fate notion of a group is that of groups competing with one another as behavioural
units. One can think here of tribal warfare, for example. The type of group selection
involved here can be called group competition by means of group interaction. The notion
of group selection associated with the interaction notion of a group is quite different.
This notion comprises both what can be called group competition without group
interaction and selective individual interaction without group competition as indispensable
ingredients. ‘Group competition without group interaction’ is intended to bring out
the idea that groups can compete for shares in a population without ever getting in
touch with one another. It is simply a matter of different growth rates (in terms of
propagating replicators in a population) how large a group’s population share turns
out to be. ‘Selective individual interaction without group competition’ it meant to
convey the idea that periodic re-assortments of groups (that, as we have seen, are
also needed to sustain altruism in a population) are brought about not by groups, but
by individuals that selectively pick out each other to form new groups.
It sometimes seems that Sober and Wilson are looking for a notion of group selection
that covers more than just group competition by means of group interaction. But it
also seems that Sober and Wilson run into conceptual problems here. It is not just
that the second notion of a group is thicker, or more substantial than the first one.
Strictly speaking, the notion of group selection associated with the interaction notion
of a group rules out the notion of group selection associated with the shared fate
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notion of a group. Consider tribal warfare or platoons in combat situations. If we
take the interaction notion, we should not speak of different groups competing with
one another, but rather of some individuals competing with other individuals of the
same group. For on the interaction notion the distinguishing feature of a group is
that its individual members only interact with each other (for some period of time). It
is clear that when it comes to tribal warfare, even though tribes can be considered to
be behavioural units, actual encounters between individual members of different
9
Other terms for the specific type of groups I have in mind here are clans, cliques and gangs.
10
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tribes are very likely to take place. But if this is so (and they do have fitness
consequences for the individuals involved!), then the interaction notion of a group
implies that the individuals involved do not belong to different groups.
In conclusion, Sober and Wilson succeed in making a convincing case for what can
be called the structured deme theme: population structure matters. But they fail to
demonstrate convincingly that taking population structure into account forces one to
take group selection in the more substantive ‘shared fate’ sense on board as well.
What outcomes emerge from evolutionary processes depend on whether there is or
is not population structure and, if so, what population structure there is. It matters
whether all individuals in a population interact with one another. If individuals for
some period of time only interact with some of the other individual in a population,
then outcomes can accrue that cannot obtain if there were no such groups. This
seems to be the whole point of ‘interaction’ group selection. It remains to be seen,
however, whether it is really meaningful to speak in all such cases of group selection
taking place alongside individual selection. I do not think it is. Especially if one’s
theoretical outlook is to reflect genuine differences in causal processes, as Sober and
Wilson argue it should, then this does not seem to make much sense. It seems that
different causal processes are going on only if there are groups in the more
substantive ‘shared fate’ sense. Thus only if there are such groups it seems to make
sense to talk of group selection. In other cases it seems to be more appropriate not to
invoke the notion of group selection and instead to talk of individual (and genic)
selection under different conditions. Individual selection can take place under
conditions of random pairing, for example, or under conditions of selective pairing.
4. Agreements and disagreements
Both EP and MST tentatively accept the adaptationist programme in evolutionary
theorising. The central presupposition guiding the adaptationist programme is that
persistent and widespread instances of organised complexity are adaptations
brought about by natural selection. It is not denied in this programme that other
forces than natural selection can be (and de facto are) driving evolutionary processes.
And it is not denied either that features or traits well adapted to circumstances
prevailing in the evolutionary past can be ill adapted to circumstances prevailing
today. What is maintained only is that natural selection is the only known
evolutionary force capable of producing enduring instances of organised complexity.
EP and MST do seem to have different reasons for accepting the adaptationist
programme, however. While EPists seem to embrace the adaptationist programme
wholeheartedly, Sober and Wilson seem to accept it only for the sake of argument.
What Sober and Wilson primarily set out to argue is that even if natural selection
were the only or all-powerful evolutionary agent, it need not work only on
individual organisms.
In endorsing the adaptationist programme EPists rely on Williams (1966). Williams
(1966, 1971) also has been one of the most ardent opponents of group selection. Yet,
although EPists seem to be somewhat sceptical of the relevance if not cogency of
group selection, they seem to leave open the possibility that group selection is a
cogent and significant force in evolution (Buss 1999). Edward O. Wilson argues that
10
An exception would be that all individuals of the one tribe surrender to those of another one without
there being any actual clash between any individuals.
11
research on epigenetic rules has pointed out that choices are group-dependent, but
he immediately adds to this that the extent to which this is the case varies strikingly
from category to category of behaviour (Wilson 1998, 227). Wilson does not go into
the issue, however, whether recognition of the group-dependence of choices entails a
theoretical commitment to group selection à la Sober and Wilson.
When discussing the possibility of psychological altruism, Sober and Wilson accept
folk psychology. They argue that assuming that their desires and beliefs (as the
proximate causes of their behaviour lead persons) is fully compatible with
evolutionary theory. By contrast EPists believe that modules of the mind are the
proximate causes of human behaviour. EPists do not seem to accept folk psychology.
What they tend to stress is that our mind’s modules predispose our behavioural
patterns in ways that we are most of the time not aware of.
No doubt more agreements and disagreements between EP and MST can be
discerned. Sober and Wilson emphasise the importance of cultural transmission in
human behaviour much more than EP does, for example. Here I want to focus on
what I take to be one of the central agreements. EP and MST, it can be argued, share
to some extent the same research agenda: how to explain (various forms of) social cooperation between non-kin? In particular, why do individual human beings that are
not genetically related to one another engage in forms of mutual co-operation even
though it is not in their evolutionary interest to do so? What is more, both prominent
EPists such as Cosmides and Tooby (1992) and Sober and Wilson relate to Axelrod’s
Evolution of Cooperation to make their respective points. Axelrod’s analysis of Tit
For Tat proves to be an interesting point of departure to discuss differences between
11
EP and MST more thoroughly.
Cosmides and Tooby (1992) embed postulating the existence of a cheater detection
module in the context of a discussion of Axelrod’s Tit For Tat. The strategy Tit For
Tat implies that cheating (or defecting) by some individual in some pairwise
encounter is reciprocated by the other individual in the next encounter between the
two. Thus Tit For Tat essentially assumes reliable and accurate detection of cheaters.
Their findings in the Wason Selection Task suggest that this assumption is realistic.
What is especially germane for the present discussion is that Cosmides and Tooby
hypothesise that the module of cheater detection evolved to solve social contract
problems. The module evolved in situations in which it was in the interest of all to
uphold some social contract. In such situations all had an interest in finding out
whether or not the confidence put in others (by co-operating themselves) was not
violated. Cosmides and Tooby further hypothesise that the cheater detection module
only is activated if people think they are in a social contract setting. In other settings
quite different modules may be activated. People may then be paying attention to
quite other things.
Sober and Wilson do not believe that by Axelrod’s analysis of Tit For Tat exhausts all
possible varieties of evolutionary altruism. But they put a lot of effort into showing
that Tit For Tatters are altruistic and that Axelrod’s explanation of the success of Tit
For Tat amounts to a specific invocation of group selection. The key to understand
Sober and Wilson’s position here is provided by the way in which they identify
11
Axelrod’s treatment is far from uncontroversial (for a cogent criticism from a game-theoretic
perspective, see for example Binmore 1994). The points EP and MST want to make here do not seem
to fully dependent on the validity of Axelrod’s treatment, however.
12
groups. In Sober and Wilson’s discussion each box of the payoff matrix denotes a
separate group (Sober and Wilson 1998, 80). In other words the population always
contains as many groups as there are boxes in a matrix. Based on this identification
of groups, Sober and Wilson focus on the following two conditions an altruistic
strategic type has to meet. First, the type must have the relatively lowest fitness in
mixed groups. And, second, the group performance should be better (again in fitness
terms) the more the altruistic type is represented in a group. They argue, for
example, that the C-strategy in a PD is altruistic because it meets both conditions. In
order to see that C meets the first condition, we have to look at the box representing
an interaction between a C- and a D-strategist. We then see that the fitness (increase)
of the C-strategist is lower than that of the D-strategist. Thus the first condition is
met. In order to see that the second condition is also met we first have to add up the
two figures in each box. We then see that the sum of the (C, C) interaction is higher
than that of the (C, D) interaction, which in turn is higher than that of the (D, D)
interaction. Thus the second condition is met as well.
This argument only makes sense, I submit, if the pairs of interactions remain isolated
for some time (for example, if there is assortative pairing). Only then, only if there is
some endurance of group competition without group interaction, does it make sense
to compare the relative ‘group’ performance of the (C, C), (C, D) and (D, D) pairs. For
only then does it make sense that the gene frequency of the C-strategy increases in
the population because the ‘group’ (C, C) grows faster than the ‘group’ (C, D), which
in turn grows faster than the ‘group’ (D, D). It is clear that this latter condition is not
met if there is random pairing (which is assumed by Axelrod).
Sober and Wilson’s analysis here once again shows, I think, how facile their
interaction notion of group selection can be. It does not make much sense to argue
that group selection is invoked in Axelrod’s account of how Tit For Tat can come to
dominate a population. It is quite contrived to distinguish two selection processes in
this case. Pace Sober and Wilson I would argue that instead of individual and group
selection jointly being at work here only individual selection is taking place. And it
also does not seem to make sense to artificially distinguish primary and secondary
behaviour here (Sober and Wilson 1998, 142-149). One cannot meaningfully argue
12
that primary and secondary behaviour evolve independently of each other here.
Primary and secondary behaviour are inextricably tied up with one another in Tit
For Tat. The threat of ‘punishments’ is built into Tit For Tat.
If there is one element of group selection in Axelrod’s account of the evolution of Tit
For Tat, it is to be found in the earliest stages of Tit For Tat entering a population of
defectors. Axelrod (and Hamilton) clearly saw that Tit For Tat has to enter a
13
population of defectors in a cluster. In this cluster Tit For Tatters must for some time
be shielded from encounters with defectors. Only after this cluster has gained some
12
Curiously enough, Sober and Wilson themselves acknowledge that primary and secondary
behaviours often evolve as a package (Sober and Wilson 1998, 146). See also Binmore for similar
criticism.
13
It is easy to verify that (given the PD matrix Axelrod uses) Tit For Tat can only invade a population
of Defectors in random pairings if the following condition is met: x > (1 - w)/(3w - 1), where x stands
for the frequency of Tit For Tatters in the population and w for the discount parameter. Conversely, in
order for a population of Tit For Tatters to resist invasion of Defectors, w must exceed 1/2. If w = 2/3,
for example, x must exceed 1/3. In this numerical example, then, the cluster of Tit For Tatters only
interacting with each other must first occupy a share in the population of at least 1/3 for Tit For Tat to
be able to spread further in the population via random pairings.
13
non-negligible size (some critical value) can Tit For Tatters spread the population in
random matings. One can say that in the earliest phase by selective pairing only with
other Tit For tatters, Tit For Tatters formed a group within the encompassing
population.
On the basis of the foregoing discussion it may be useful to introduce a taxonomy of
different forms of altruism. Let us define altruism somewhat loosely as a behavioural
disposition that, if activated, prompts individuals to do things that enhance the
welfare (or well-being, or…) of other individuals at the expense of one’s own welfare
(or well-being, or…). Note that I do not define altruism here in terms of antecedent
intentions for, or causes of behaviour. The definition does not tell why or how
altruistic behavioural dispositions are triggered. Then we can distinguish at least
14
between the following four forms of altruism.
1. Unconditional altruism: an individual is unconditionally altruistic if it always
displays altruistic behaviour regardless of the individual(s) it interacts with.
2. Like-seeks-like altruism: an individual is like-seeks-like altruistic if it always
displays altruistic behaviour regardless of the individual(s) it interacts with, but
that prefers to interact only with like-minded altruists.
15
3. Groupism: an individual is groupish if it only displays altruistic behaviour in
interactions with fellow group members.
4. Content-specific altruism: an individual is content-specific altruistic if it only
displays altruistic behaviour when provided with stimuli with the appropriate
propositional content.
Both unconditional and like-seeks-like altruism relate to fixed behavioural types (or
to individuals following fixed strategies). In both types a disposition to behave
altruistically is activated regardless of what properties the individuals interacted
with have. No matter whether the individuals interacted with are genetically related,
friends, like-minded altruists, fellow group members or anonymous strangers,
unconditional and like-seeks-like altruists always behave altruistically. The only
difference between like-seeks-like altruists and unconditional altruists is that the
former prefer to interact only with like-minded altruists. This means that if likeseeks-like altruists are given the chance, they will only interact with like-minded
altruists, leaving other types to themselves. Note that the latter does not imply that
like-seeks-like altruists are always able to act on this preference. Opportunities for
selective play (or pairings, or matings) may be absent temporarily or permanently.
Groupish individuals do not always behave altruistically. Groupish individuals only
behave altruistically towards fellow group members. Note that groupish individuals
need not prefer to interact only with fellow group members or like-minded groupish
individuals. The behavioural disposition involved in this type of altruism has a
conditional structure. When activated, the disposition prompts altruistic behaviour if
there is interaction with fellow group members, and non-altruistic behaviour if other
conditions obtain. A strong form of groupism is displayed if the disposition to
14
I do not claim that the list provided exhausts all possible forms of altruism. Far from that. But I
believe that it allows us to clarify relevant differences between positions taken in EP and MST.
15
It can also be argued that groupism is not a particular form of altruism. It can also be called a
separate third possibility next to egoism and altruism (Gilbert 1994).
14
behave altruistically is always activated whenever a fellow group member is
encountered. Contrast this with content-specific altruism where the disposition to
behave altruistically is activated only under certain circumstances. Here the
disposition itself need not have a conditional structure. It is rather that it is only
activated if the right conditions are met. Only if the stimuli have the right content is
the disposition to behave altruistically triggered. This leaves open the possibility that
the ‘altruistic disposition’ is not triggered in some interactions with fellow group
members, whereas it is triggered in encounters with individuals not belonging to
one’s group.
Both Axelrod and Sober and Wilson, in their interaction notion of group selection,
seem to invoke like-seeks-like altruism. Axelrod’s analysis of the evolution of Tit For
Tat assumes that in the earliest stages Tit For Tatters can act on their preference to
interact only with other Tit For Tatters. Only after the frequency of Tit For Tatters has
exceeded some critical threshold value can Tit Fir Tat further invade a population of
Defectors through random pairings. In their interaction notion of group selection
Sober and Wilson assume that individuals of different ‘groups’ first do not interact
with each other for some period of time, but that after that the barriers are lifted.
When the barriers are lifted, altruists are assumed to seek other altruists to form new
groups. Then the newly formed groups are assumed to be isolated again for some
period of time, and so on. As far as I can see, the most plausible interpretation of this
ongoing sequence is that altruists prefer to interact only with fellow altruists, but are
sometimes temporarily prevented from acting upon this preference. If they are
temporarily locked in groups, they cannot escape from interacting with whatever
types (non-altruists included) are present in their group. But if the borders open up,
they can escape being exploited by free riders by acting upon their preference to
interact only with like-minded altruists.
But if my interpretation makes sense, then Sober and Wilson owe us an explanation
of why individuals are temporarily are stuck within their own ‘group’, why after that
they are perfectly free to find like-minded individuals to form new groups, and why
and how after that groups once again are closed off from each other. With certain
types of animals, plausible stories can perhaps be told about why we would observe
such sequences or cycles unfolding. The story Sober and Wilson tell about the brain
worm, for example, is fascinating and convincing in this respect (Sober and Wilson
1998, 18). But with human beings, the situation may be different. Even if we assume
that persons are of a fixed behavioural type, it seems that we cannot ignore the
possibility of migration. Only under very extreme circumstances, it seems, can
persons be prevented from moving over to other ‘groups’ (or to found new ones).
Groupism seems to be quite close to Wilson and Sober’s shared fate notion of group
selection. The notion of groups competing with one another as well-integrated units
(or as ‘superorganisms’) suggests the combination of in-group solidarity and outgroup hostility characteristic of groupism (Gilbert 1994). Individuals here need not
prefer interaction with fellow group members. Indeed, they may even be more eager
to engage in combat with individuals of competing groups than to seek contact with
fellow group members. Content-specific altruism, finally, seems to be depicted in EP.
If people perceive situations and problems in terms of upholding some social
contract, EP argues, then a disposition to behave altruistically is triggered. But if they
perceive situations differently, for example as a situation in which their position in
the pecking order in a group is endangered, quite a different disposition may be
triggered. They may engage in competitive status-protecting and status-seeking
15
behaviour within the group then. What this shows, I think, is that EP allows for the
possibility that group members need not always behave altruistically towards one
another. Conversely, EP in principle also seems to allow for the possibility that
altruistic behaviour is directed towards individuals that do not belong to one’s own
group. It all seems to depend on whether individuals are faced with the right stimuli.
This raises the interesting question whether EPists believe social contracts can be selfsustaining also on larger scales than relatively small-sized groups.
5. What difference does it make for economics?
EP and economic theory
Several economists have reflected on the possible significance of EP for economics.
Not surprisingly, perhaps, economists of different persuasions reached different
conclusions (for a more detailed discussion, see Vromen 1999 and 2001b). In this part
of the paper I want to focus on economists who argue that EP is of interest for
economics mainly because it holds out the prospect of providing a non-arbitrary
identification and explanation of the preferences people actually have. I am thinking
here, for example, of Ben-Ner and Putterman (1998 and 2000), Zywicki (2000), Gintis
(2000) and work done in the so-called ‘indirect evolutionary approach’. Although no
explicit references are made to the EP literature in this latter approach (as far as I
know), I believe it is very much in the same spirit.
In order to see what message the ‘indirect evolutionary approach’ entails for
economics, let us have a look at Güth and Yaari (1992), the paper in which it was
introduced. Güth and Yaari (1992) set out to show how a genetically determined
preference for reciprocal behaviour could possibly have persisted in ruthless
selection processes. In order to do this, Güth and Yaari consider a simple game in
extensive form with two players. They confine their attention to an analysis of two
different ‘gene types’ (as players): one player is assumed to be genetically disposed
to reciprocate harm with harm, whereas the other player is assumed to be genetically
disposed to yield to a harming opponent. Güth and Yaari then show (assuming in
addition complete information and individual rationality) that the reciprocating type
is the only Evolutionarily Stable Strategy in the game. The interesting thing about
this result is that, appearances notwithstanding, a preference to reciprocate is
reproductively successful, not despite but precisely because of its determined
reciprocating nature. Precisely because people genetically endowed with a
preference to reciprocate are determined, regardless of the personal costs involved in
doing so, to harm others if these others harm them (and the others know this), can
16
they avoid being exploited by others.
What makes Güth and Yaari’s evolutionary approach indirect rather than direct is
that evolutionary forces and pressures are assumed to affect our behaviour
indirectly. By contrast, evolutionary game theory assumes that selection pressures
mould (or, rather, moulded) our behaviour or our behavioural strategies directly.
The basic idea underlying the indirect evolutionary approach is that selection
pressures determine what preferences (or preference profiles) evolve. And our
16
The crux of the matter here, it can be argued, is that ‘subjective’ valuations (determining what the
players do) are different from ‘objective’ results (determining what type has survival value).
16
preferences in turn guide our behaviour. The indirect evolutionary approach’s basic
logic, Huck writes, is that “… preferences guide behavior, behavior determines
fitness, and fitness drives the evolution of preferences” (Huck 1997, 773).
It may appear that we come full circle here. But for three reasons there is no
circularity involved here. First, there is temporal order. The preferences guiding our
behaviour now evolved in the past. Second, what we prefer need not coincide with
what is selected for. As Güth and Yaari’s example illustrates, what subjective
valuations people attach to certain options have may differ from the options’
objective (expected) reproductive success. “While choices are motivated by the
preferences, which may include an internal commitment to norms, objective
evolutionary success of preference types depends on "external incentives.”” (Güth
and Ockenfels 2000, 396). Third, and perhaps most importantly, preferences do not
fully determine behaviour. To determine what behaviour follows from certain
preferences, additional information has to be provided (or: additional assumptions
have to be made). Güth and Yaari explicitly state that “… we assume individual
17
rationality for given preferences” (ibid., 23). What is the rational thing to do depends
not just on prevailing preference profiles, but also on prevailing constraints and
opportunities. Thus in the indirect evolutionary approach we are not taken to be
prisoners or puppets of these evolutionary processes. Even though we may be called
prisoners of our preferences, the indirect evolutionary approach “… does not neglect
individual’s ability to adjust their behavior in different environments when studying
a selection process” (Huck, 1997, 777).
Proponents of the indirect evolutionary approach acknowledge that their approach is
reminiscent of Becker’s views on how economics and sociobiology could be merged
(see Huck 1997 and Bolton 2000). Becker was one of the first economists to spot the
potential use the then emerging field of sociobiology could have for economics. In
Becker (1976) an attempt is made to merge sociobiology with economic theory. One
of the things economists can learn from sociobiology, Becker argued, is that people
with altruistic preferences (such as ‘Big Daddy’) can survive in a harsh, ‘material’
world. Becker believed sociobiology would not in any way contravene standard
economic analysis. They rather complement each other nicely. Economists can teach
sociobiologists that rational individuals sometimes can act quite unexpectedly. Thus
altruistic ‘Big Daddy’ can evoke co-operative behaviour from a selfish ‘Rotten Kid’.
Conversely, sociobiology can tell us, Becker hoped, what preferences our
evolutionary past has passed on to us, and economic theory can tell us how to act
rationally upon them. One may say that evolutionary psychology, as an heir of
sociobiology, now is cashing in this hope. We may even go further back in time and
say that with the advent of evolutionary psychology, psychology finally delivers
what Robbins (1932) once hoped psychology could offer to economics: firmly
established knowledge about our preferences.
This ‘Beckerian’ mix of sociobiology and standard economic analysis, we have seen,
can also be observed in the indirect evolutionary approach. Proponents of this
approach also set out to demonstrate why in the one situation a single selfish
individual is capable of inducing non-selfish individuals to behave non-cooperatively, while in another situation a single non-selfish individual is capable to let
selfish individuals behave in a co-operative way (Fehr and Schmidt 1999, 819). All
17
Witness also Bolton’s characterisation of the approach: “…conceptualizing evolution as working on
preferences, and then applying rational choice to explain actual decision making” (Bolton 2000, 286).
17
this leaves the basic analytical structure of economic theory intact. As Huck argues,
there is no need “… to forsake the elegance provided by the tools of neoclassical
economics” (Huck 1997, 773).
It may well be, however, that the real lesson evolutionary psychology entails for
economics is less consoling for received economic theory. For evolutionary
psychology may imply a somewhat different picture of the ‘given’ determinants of
our behaviour and of how they interact with the environment to produce behaviour.
Evolutionary psychology may undermine the picture of fixed preference profiles that
are invariant across different situations. The point is not so much that evolutionary
psychologists object to the idea that we have fixed preferences. The innate modules,
mechanisms and rules they are talking about can be called (and sometimes are
called) preferences. The point rather is that the modules do not constitute a unitary
whole that is operative across different situations. Evolutionary psychologists may
believe that there is a universal and uniform human nature. But they do not believe
human nature to be unitary. The different modules cannot be thought of as different
terms in an all-embracing and all-purpose utility function. If one would nevertheless
want to cling to the notion of a utility function, each module represents a separate
utility function, the relevance of which is restricted to a special purpose only.
Human nature, as depicted by evolutionary psychology, is fragmented. Invariant
preference profiles and all-embracing, all-purpose utility functions suggest a unity or
homogeneity in the determinants of human behaviour that according to evolutionary
psychologists simply is not there. Contrary to what the notions of an invariant
preference profile and of an all-embracing and all-purpose utility function suggest,
there are no tradeoffs between the mind’s modules. There are no tradeoffs between
modules because not all modules are operative in all situations. Typically, only one
module (or a few modules at most) is activated in a situation. The other modules
remain inactive. They are in the switch-off mode, as it were.
The economists discussed above assume that the motivation profiles of individuals
are invariant across different contexts. Behaviour may still be context-dependent,
because different contexts provide different opportunities for individuals. By
contrast, evolutionary psychology seems to hold that motivation profiles themselves
are context-dependent. To be more precise, individuals are assumed to have several
behavioural dispositions, each of which is ‘switched on’ in suitable environmental
contexts. Behaviour is context-dependent not because opportunities differ from the
one context to the other. Behaviour is context-dependent because different contexts
bring different stimuli with them triggering different modules.
Moreover, modules do not bear only on the evaluative aspects of our behaviour.
They do not relate only to what we desire, value, cherish and so on. They also relate
to how we think and learn and how we arrive at our behaviour. In other words,
cognitive aspects are also involved. Evaluative and cognitive aspects, it seems, are
inextricably interwoven in the operation of modules. As Wilson argues, epigenetic
rules do not only determine what things we value and how much we value them.
They also determine what options we consider in our attempts to obtain the things
we value most. And they also determine the heuristics we entertain in our ‘prepared’
search behaviour. In short, they also affect the cognitive aspects of our behaviour.
Sometimes our epigenetic rules enable us to act rationally. But in other cases they do
not. Our behaviour is too diverse and heterogeneous to be subsumed under the
parsimonious general laws of rational choice theory (see also Wilson 1998). Seen in
18
this perspective, the fault the economists discussed above make is that they
erroneously believe that economic theory’s basic assumption can be retained that in
analysing behaviour affective or evaluative and cognitive aspects can be neatly
distinguished.
Group selection and methodological individualism
Sober and Wilson argue that rehabilitating group selection also provides an effective
antidote to the influential doctrine of methodological individualism (MI) in the social
sciences (Sober and Wilson 1998, 133, 329). MI has many staunch advocates
especially in economics. In this subsection I examine whether Sober and Wilson’s
argument should convert these staunch advocates.
MI is the doctrine that explanations of phenomena at the social or aggregate level
should refer only to individuals, their properties, actions and interactions.
Explanations in terms of properties, actions and interactions of supra-individual
entities are discarded. Thus the doctrine rules out that, for example, (changes in) la
volonté generale (the ‘general will’) or das gesundenes Volksempfinden are referred to in
order to explain changes in the legal system of some country. If there exist things
such as the general will at all, advocates of MI insist, then they cannot be but
outcomes of actions and interactions of individuals. And if so, they also have to be
ultimately explained in terms of the actions and interactions of individuals.
What the example just given also indicates is that the refusal of MIsts to accept
supra-individual entities as explanatory variables is to a large part extent based on
the belief that supra-individual entities are ontologically suspect. Can something like
the general will be said to exist at all? Is it not just a shorthand way of speaking about
things that really do exist: the citizens of some country and their values, desires,
beliefs and causal powers? Invoking groups as explanatory variables raised the same
suspicion with proponents of MI. Can groups be as real as individuals? Or is the
existence of groups only derivative (on the existence of individuals as the elementary
units) and talk of groups only a convenient way of speaking without real ontological
18
underpinning? And if the latter is the case, then should we not refer to the
19
individuals that form groups rather than groups in our explanations?
Do Sober and Wilson prove MI to be mistaken? Once again, I think, we should
distinguish between the interaction and the shared fate notions of groups and group
selection. Proponents of MI would find nothing to quarrel about in the interaction
notion, I submit. The ideas that population structure matters and that there can be a
combination going on of group competition without group interaction and selective
individual interaction without group competition are fully compatible with MI.
Proponents of MI would hold (and rightly so, I think) that explanations in terms of
groups and group selection here are misleading. In fact, individuals, acting under
different circumstances and with different opportunities, are the only active agents
here.
Things may be different with the shared fate notion of groups and group selection.
Here the leading idea is that if we accept individual organisms as elementary units in
our explanations (as proponents of MI do), then there is no good reason to reject
18
Perhaps work in ‘social ontology’ will shed more light on this. See also Sugden’s interesting work on
team preferences and team reasoning (Sugden 1993 and 2000).
19
But we must be careful here, since many professed proponents of methodological individualism have
seen no problem in accepting ‘supra-individual’ firms and households as explanatory individuals.
19
well-integrated groups of individuals having a shared fate as elementary units in our
explanations. For groups liken individual organisms in that they also have to cope
with the permanent danger of mutiny from within. If we are willing to accept wellintegrated individual organisms, that do reasonably well in coping with this internal
problem, as legitimate explanatory units, then we should also accept well-integrated
groups of individual organisms. What matters is how well entities (at any level of
organisation) are integrated internally. On this criterion, groups acting as
superorganisms qualify.
Maybe so. But if the notion of superorganism is meant to convey that the bonds
between group members are so tight and strong that they will never be broken, then
such groups rarely exist if at all (Ridley 1996). Basing one’s theory on such
exceptional groups would surely imply an unduly restrictive view on groups. The
shared fate notion of a group seems to imply a sort of fatalism on the part of group
members that many (not just proponents of MI) will find hard to accept when
discussing human behaviour. The shared fate notion essentially says that if a group
dies off then its individual members go ‘through the drain’ with it. It is as if
individuals do not have any escape option. Or if they do, individuals are portrayed
here as passive creatures patiently waiting what happens to their group all up to the
point that they themselves pass away. They do not take any initiative to curb their
own fate. This seems to strain credulity. It seems obvious, for example, that
individuals can leave their group, join other groups, found new groups and so on.
At least Sober and Wilson owe us an explanation why individual members of groups
as superorganisms do not seize these opportunities. Why would people not try to
leave a group, if they think it is a ‘sinking ship’, before it is too late? What prevent
them from doing so? I do not think Sober and Wilson offer an explanation for this.
But they do mention secondary behaviours and social norms as mechanisms, unique
to human groups, which at least suggest possible explanations. Explanations based
on these mechanisms would assume that group members are punished if they do not
display (their part in) mutually beneficial primary behaviours or if they do not
respect the group’s social norms. The most severe form of punishment, Sober and
Wilson suggest, is ostracism or expulsion from the group. This seems to presuppose
that group members perceive membership of the group as something they want to
retain at any cost. But exactly this presupposition can be called into question, I think.
If group members believe their whole group is about to be eliminated, they may well
want to leave the group.
This is not to argue that there are no possible ways in which individuals may be
prevented to leave the group also in such critical situations. One may think here of
groups having implemented severe punishments on desertion, for example. I do not
want to argue either that plausible notions of groups and group processes cannot be
found that seem to contradict MI. Sometimes it seems that groups, even if they are
formed or founded by individuals, can get to live ‘a life of their own’. They may
exhibit ‘emergent properties’ that are not fully reducible to the properties, actions
and interactions of individuals. Groups may ‘survive’ replacements of one set of
individuals by another one having quite different personal properties, for example.
Such groups may also have a profound influence on essential properties of their
members. My point here simply is that Sober and Wilson do not advance compelling
20
arguments, neither in their interaction nor in their shared fate notion of a group, to
20
reject MI.
Co-evolution and economic processes
Even if we were to conclude from the previous discussion that human groups are not
entities sui generis, this does not imply that groups need not be taken into account in
analyses of economic processes. Human groups can be ephemeral. Yet the ways in
which ‘populations’ are structured in groups and in which groups interact with one
another may have a profound impact on how economic processes unfold.
Let us first return to Sober and Wilson’s discussion of the function of culturally
transmitted norms in human groups. Sober and Wilson argue that each human
group has developed its own set of norms. They believe that evolutionary game
theory sheds an interesting light on how such evolutionary processes unfold. Once
we have several groups with their own norms in the population, processes of group
selection take off, favouring the most functionally adaptive ‘altruistic’ ones (Wilson
and Sober 1998, 151-2).
The overall picture emerging here is the following. Before group selection starts to
operate there is individual selection going on, leading to groups all having their own
21
distinct set of norms. Only after each group has established its own norms, group
selection starts to work on them. And once group selection takes off, the norms of the
groups do not change anymore. Thus this picture essentially involves two things.
First a temporal order is implied. Processes of individual selection are assumed to
precede processes of group selection. And, second, a causal asymmetry between the
two types of processes is implied. Group selection is causally dependent on
individual selection in the sense that group selection works on the products of
individual selection. In this sense there is scaffolding (or cumulative causation, if you
like). Conversely, individual selection is in no way causally affected by group
selection. Processes of group selection are assumed not to have a feedback on
processes of individual selection (in this particular case: on the evolution of norms).
The picture is neat. But is it also realistic? Work in social psychology on group
dynamics suggests it is not (Tajfel 1981). What happens within groups, how groups
evolve over time seems to depend both on intragroup and on intergroup processes. In
particular, the social identity of group members seems to evolve as a consequence of
both processes. The social identities of individual group members get their shape
(and are reshaped) partly in response to exchanges and encounters with (menbers of)
other groups. This point can be generalised by saying that there is co-evolution going
on. Once there are groups, individual and group selection work simultaneously
mutually affecting each other. In this complex combined process there are no ‘fixed
points’. It cannot be assumed that individual selection yields products that are
unaffected by the dynamics of intergroup interaction.
Bringing the discussion closer to home (economics, that is) now, it seems that in
analysing economic processes different levels (or layers) of organisation are to be
reckoned with. What is more, what is going on at some level of organisation seems to
depend both on what is going on at lower levels and at higher levels. Let me try to
20
It also remains to be seen whether individual selection is compatible with MI. See Vromen (2001a)
for discussion.
21
As indicated earlier, I believe that applying evolutionary game theory in this way implies that it is
assumed that individual selection is going on.
21
elaborate a bit on this. In economic theories of organisation it has become
commonplace to argue that three levels of organisation should be taken into account:
the individual, the organisation and the market (or industry). Thinking about groups
and group selection now, can the firm be treated as a group? It seems that in some
respects it can. It can be argued that firms display some unity and compete with one
another in the market. But, as Campbell (1994) has argued convincingly, especially in
larger firms it seems more plausible to locate groups in between individuals and the
firm as a whole at the level of face-to-face cliques. Within a firm, individuals who
regularly interact with another in non-anonymous ways tend to form a clique with
22
its own shared beliefs, codes of behaviour and rituals (Campbell 1994, 30). What
beliefs, codes of behaviour and rituals evolve does not depend only on the types of
individuals entering the clique (at ‘one level below’), but also on how the clique is
situated, and interacts with other cliques within the same firm (at ‘one level above’).
In other words, there is co-evolution going on.
What is interesting in Campbell (1994) is not just the suggestion that in order to get a
better understanding of firm processes a level of face-to-face groups has to be
inserted in between the levels of the individual and of the (large scale) firm.
Interesting is also the suggestion that face-to-face group selection tends to undermine
rather than support the market performance of firms. Face-to-face groups tend to
display a combination of ‘clique selfishness’ and outgroup hostility (this combination
I called ‘groupism’ earlier on). The resulting antagonisms within the firm tend to
undermine the firm’s functioning as a whole. This is a refreshing antidote, I think, to
those organisational theorists who over-optimistically argue that selection processes
working at different levels mutually reinforce each other in the direction of Paretooptimal outcomes. Such a perfectly harmonious picture is drawn, for example, by socalled agency cost theorists (such as Jensen, Meckling and Fama; see Vromen 1995 for
further discussion). The point Campbell makes here is perfectly compatible with one
of the main things Sober and Wilson argue for: selection processes working at
different levels of organisation tend to work in opposite directions. Thus conceived,
Sober and Wilson’s MST can serve as some sort of reminder in organisational
studies: don’t assume too easily that selection processes operating at different levels
of organisation work in the same direction.
6. Concluding remarks
The harvest of this paper may seem poor. Its results are programmatic and
promissory rather than substantial and ready-made for ‘consumption’ in economics.
A lot work is still to be done both within EP and MST and in efforts to flesh out their
implications for economics. Those insisting on immediate gratification in
interdisciplinary learning are likely to be disappointed. On the other hand it can be
argued, I think, that the prospects are promising. MST primarily holds out the hope,
it was argued, of coming to grips with a vexing issue that has long intrigued many
economists: how to comprehend co-evolution at different levels of organisation? And
the contribution of EP to economics may well lie, I argued, in its ability to tell what
22
Experiments in social psychology suggest that groups that are formed arbitrarily ex nihilo
immediately start developing their own codes of behaviour and rituals. And among its members
immediately ingroup feelings arise spontaneously.
22
23
behavioural patterns are enticed under different conditions and stimuli. Once we
have a better understanding of this, we may also know better not only what sorts of
behaviour are inevitable, but also how to avoid behaviour that we want to avoid and
how to stimulate behaviour that we want to promote. Thus EP could also prove to be
of interest for normative and policy issues. The latter also indicates how far
contemporary evolutionary theory already has distanced itself from the idea that we,
human beings, are puppets of our genes and memes.
No doubt many will find that culture and cultural evolution are given short thrift in
EP and MST. And many will also hold that it is better to turn to other social sciences
and theories about cultural evolution and start there. But I believe we better start
with improving insights into our biological heritage and adaptations that enabled the
human species to get its specific types of culture and its specific types of cultural
evolution off the ground (in phylogenetic time). I think it makes sense to start there
and see how far we can get with it. Probably the picture will turn out to be more
complex than we can now envisage. We may still have a long way to go, but I think it
is worthwhile to continue travelling it.
23
EP may well be able to explain why we tend to behave self-regardingly in some situations while in
other situations we tend to behave other-regardingly. EP also may be able to shed some light on
otherwise puzzling findings in experimental economics (Hoffman, McKabe and Smith 1998).
23
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