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AppendixA Proposal for the Evolution

and Development of Free WillEddy Nahmias

1. IntroductionThis dissertation has argued that free will is constituted by a set of cognitive abilities,

which allow us to introspect on our motivational states and evaluate themto know our own

mindsand to act on this knowledge. Rather than requiring a unique metaphysical ability (such

as contra-causal powers), this view sees free will as coming in various degrees. And in normal

adult humans these abilities are particularly well-developed (in a way that supports reactive

attitudes and moral responsibility, allowing for our social and legal practices). We want to know,

then, how it is that these abilities have become relatively advanced in humans, and how they

become more advanced as humans grow up. We should, therefore, look for naturalistic

explanations for the existence of free will: How, as a species, did we evolve free will? And how,

as individuals, do we develop free will?

From our vantage point, it may seem obvious that possessing the sorts of knowledge about

oneself and the world, which I have associated with free will, would provide a clear selective

advantage. An animal with the ability to predict its own behavior by being aware of its various

desires and their possible outcomes in the world would surely increase the animals rate of

survival and reproduction relative to conspecifics that lacked this ability. The story would go like

this: Most animals react differentially to their environment, moving towards what has helped their

ancestors survive and reproduce, or what has positively reinforced them in the past, and moving

away from what has killed their ancestors, or what has negatively reinforced them. These

motivationsgenetically derived or behavioristically learnedare crucial to the animals survival

and reproduction. However, they are based on mechanisms which drive the animal to act on

whichever motivation is strongest at a given time (like Frankfurts wanton). But the strongest

motivation is not always the most advantageous for the animal, given other factors in its

environment and given its longer-term prospects (e.g. a subordinate monkey acting on his

motivation to mate may never reproduce if the dominant kills him or expels him from the group).

Hence, there should be selective pressures for the ability to inhibit ones immediate desires and

allow for increased flexibility of behaviorjust as behavioristic learning allows more flexible

responses to variable environments than genetic mechanisms. If only an animal could consider

whether or not to act on its strongest motivation. One way this might occur is if the animal could

represent itself in its environment, represent various actions (based on its various motivations),

and represent likely outcomes of those actions. That is, an animal that could know its various

motivations, imagine their likely outcomes in the world, and act accordingly would do well in

comparison to an animal that just acted on its immediate desires. Basically, there should be

selective pressures for the abilities I have associated with free will;persons should be able to

survive and reproduce better than wantons.

Thats a plausible story. But it leaves way too many questions unanswered. For instance,

what particular environmental features (social and physical) would select for these

representational cognitive abilities? And from what prior traits (e.g. cognitive structures) might

these abilities arise? Not every potentially advantageous trait evolves (not even close); it takes the

right mutations in the right selective environment. And you cant get something from nothing;

complex traits do not evolve without precursors (any more than adult human beings arise from


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swamps). To provide even the beginnings of a plausible evolutionary account for a particular

trait, we need a lot more information.1

We need to know, for instance, which creatures have the

trait in question and which of their nearest relatives dont, and which features of the environment

in which they evolved might have made the difference. And we need to know what primitive

traits might have served as the building blocks for the derived (evolved) trait. As with other traits,when dealing with cognitive abilities, there should be no inexplicable differences in kindbetween

related species abilities. As Darwin stated: If no organic being excepting man had possessed

any mental power, or if his powers had been of a wholly different nature from those of the lower

animals, then we should never have been able to convince ourselves that our high faculties had

been gradually developed. But it can be shewn that there is no fundamental difference of this

kind (1871: 445).

Agent causation seems to attribute to humans a wholly different nature from any other

animal (not surprising given its historical connection to immaterial souls). An evolutionary

account of free will must locate it in abilities (or powers) that can be traced to ones possessed by

other animals.2

But even the abilities to introspect on, identify with, and influence our

motivations in the way I have described seem to involve significantly different powers than thosepossessed by other animals. Indeed, Darwin, recognizing the significance of such abilities, seems

to contradict the claim I quote above when he writes: A moral being is one who is capable of

comparing his past and future actions or motives, and of approving or disapproving of them. We

have no reason to suppose that any of the lower animals have this capacity (1871: 88-89).

However, our apparent uniqueness can be explained, in part, because many human

ancestors, which may have possessed intermediate cognitive abilities between those displayed by

modern humans and by our nearest living relatives, are extinct. Hence, we will need to look for

lower-level building blocks of the cognitive abilities required for full-fledged free will. I believe

we will find them in more basic representational abilities, including perhaps the ability to

recognize others as self-moving agents rather than objects, the ability to imitate others and

respond to what they see, the ability to inhibit ones immediate impulses, and the ability to predictones own and others behavior based on internal states. This last ability, to represent

motivational and perceptual states, is sometimes referred to as theory of mind.

Theory of mind, I will suggest, offers a foundation for the introspective abilities required

for free will. By surveying theories and experiments from several fields, including developmental

and comparative psychology, I offer a proposal for the evolution and development of these

representational cognitive abilities. My proposal deals with the evolution of theory of mind in

primates and its development in very young children. I leave it to others to advance proposals for

how these foundational ablities develop into full-fledged free will as children grown up in an

appropriate social setting.

2. The Basic Idea

1See Brandon (1990: 165-176) for the criteria required for a complete adaptation explanation. In the proposal below,

I will provide evidence for some elements of such an explanationprimarily for an evolutionary trend suggesting

selection has occurred and a description of the selective environment in which the trait is adaptive. I will not offer

evidence of heritability or patterns of gene flow in populations.

2See Waller (1998).


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My proposal seeks to link together ideas from several areas of recent research in primate

social behavior and cognition and in child development. It begins with Robert Trivers model for

reciprocal altruism, a system in which individuals exchange benefits over time. This model has

been used to support theories about the evolution of human ethical systems and moral emotions.

For instance, Frans de Waal writes, there can be no morality without reciprocity.3

However,few researchers have latched onto the final sentence of Trivers original paper, where he suggests

that reciprocal altruism may have led to the evolution of cognitive abilities and increases in brain

size:

Given the psychological and cognitive complexity the system [of reciprocal altruism]

rapidly acquires, one may wonder to what extent the importance of altruism in human

evolution set up a selective pressure for psychological and cognitive powers which partly

contributed to the large increase in hominid brain size during the Pleistocene. (1971: 223)

While Trivers suggests thatthis may be the case, I want to suggest how it may have

occurred. I propose that a complex social environment involving reciprocal altruism selects for

deception and detection of deception, in turn, creating a sort of feedback loop selecting forincreasingly advanced abilities to understand how ones own and others mental states are

predictive of future behavior.4

Put simply: sharing selects for cheating, and cheating selects for

catching cheats, and both of these select for mind-reading.

Here, my proposal turns to the growing body of research on theory of mind and deception

in animals and children. Robert Premack and Guy Woodruff introduced the concept of theory of

mind to describe a chimpanzees ability to predict how another agent would behave, given his

apparent goals:

In saying that an individual has a theory of mind, we mean that the individual imputes

mental states to himself and others. A system of inferences of this kind is properly called a

theory, first, because such states are not directly observable, and second, because the

system can be used to make predictions, specifically about the behavior of otherorganisms. (1978: 515)

An animal that can ascribe to another agent mental states, which unify broad classes of behavior

into patterns of beliefs and desires, can better predict the agents future behavior.5

While

3de Waal (1996: 136). Sociobiology is largely based on kin altruism and reciprocal altruism, and evolutionary ethics

and evolutionary psychology draw heavily on these theories.

4The evolution of these cognitive abilities may also account for at least some of the increase in hominid brain size

that Trivers refers to: modern humans have brains that, relative to body size, have increased in size roughly threefold

since we shared a common ancestor with chimpanzees about 5-6 million years ago.

5This is true regardless of whether we want to say that the other animal actually has these states, so that the

philosophical question of eliminativism can be avoided. All that is necessary is that the theory actually serves to

unify behaviors under unobservable mental attitudes, such as desires and beliefs, and is effective in making accurate

predictions about those behaviors. See, for instance, Astington (1993, chap. 2). Furthermore, as Humphrey points

out (1983, 36), an animals own mental states, its introspected conscious experience, do not need to be the same as

anothers for introspection to be advantageous; it only needs to function to predict the others behavior.


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cognitive ethologists continue theory of mind research on monkeys and apes, it has also

blossomed in developmental psychology, where researchers such as Henry Wellman and Joseph

Perner have shown that children develop the ability to represent others mental states in stages.

Building on the abilities to imitate and make believe, children in their third year develop the

ability to explain and predict others behavior based on their motivational states (desires). But notuntil their fourth year do children demonstrate an understanding of others informational states

(beliefs) as well. Finally, children sometime after the age of four come to recognize that others

beliefs (and their own) can be distinct from the way the world actually is and thus can be false.

The development of increasingly complex deception parallels these stages, which should

not be surprising, since the more complex forms of deception seem to require false-belief theory

of mind, since they require understanding that others beliefs can be different than ones own and

hence can be made different than what one knows to be the case. Four year olds, who pass false-

belief theory of mind tests, also begin to employ intentional deception, where an individual A tries

to make B believe something to be true which A knows to be false. Such deception can be

contrasted with younger childrens lies, which are based simply on what has (sometimes)

worked in the past, such as a childs saying Im tired to avoid doing what she doesnt want to do(the simplicity of such misrepresentation becomes evident when the child says Im tired to avoid

being put to bed).6

Researchers such as Richard Byrne and Andrew Whiten have gathered evidence of

deception in primates, and have found that apes deceive in more complex ways than monkeys

(while prosimians do not seem to deceive at all). They undertook this project to advance their

theory that the complexities involved in manoeuvring in ones social environment (rather than just

dealing with ones physical environment) created selection pressures for particular aspects of

primate and human intelligence:

It is suggested that it is the evolution of social intelligence which explains human brain

power, and that this is a relatively recent step in the sequence of phylogenetic elaboration

in social intellect which is reflected not only in human superiority over other contemporaryapes, but in their superiority over monkeys, and in monkeys superiority over prosimians.

(1988: 2)

Nicholas Humphrey was one of the first researchers to suggest social complexity as the most

significant factor driving increased primate intelligence. As he states:

There are benefits to be gained for each individual member [of a social group] from

preserving the overall structure of the group, and at the same time from exploiting and out-

manoeuvring others within it. Thus, social primates are required by the very nature of the

system they create and maintain to be calculating beings. (1976: 19)

Humphrey believes social complexity will lead to cooperation, but it also creates opportunities toexploit conspecifics. One of the outcomes of this evolutionary trend is our ability to be (folk)

psychologists, to introspect our own mental states so as to predict others behavior. Humphrey

calls this introspective ability, which is essentially theory of mind, reflective consciousness.

6See Perner (1991: 189-200).


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My proposal for the evolution of human intelligence ends up in the same place as

Humphreys. However, my goal is to explain more fully how we got therethat is, to explain

why animals might be selected to be aware of their own and others mental statesto have a

theory of mind. Specifically, animals in a complex social system which involves reciprocal

altruism are poised between cooperation and competition. This leads to selective pressures fordeceptive behavior, usually subtle cheating aimed at gaining more than one gives in a cooperative

relationship. However, for reciprocal altruism to maintain itself, it requires a mechanism to detect

these cheats and deny them reciprocity. Thus, detection of deception would be selected, along

with the emotional motivations to withhold reciprocity from and perhaps punish cheats. These

pressures to deceive and to detect deception create a feedback loop, leading to increasingly

complex levels of theory of mind.

The most basic level is desire theory of mind which allows an animal to be a sort of

behavioral psychologist, predicting others behaviors according to their desires for rewardsand

perhaps thwarting others desires when they conflict with ones own. The next level, belieftheory

of mind allows an animal, acting more like a cognitive psychologist, to predict specifically how

another animal, given its beliefs (its perceptions and perhaps memories), may attempt to satisfy itsdesires. Finally,false-belieftheory of mind allows an animal to manipulate anothers beliefs so

thatthey misrepresent realityand perhaps to notice when ones own beliefs are being

manipulated. Indeed, this purposeful misrepresentation is what we generally mean by deception,

and this detection of deception is tied to our understanding of others intentions.7

Thus, my proposal attempts to bridge together several areas of research to come up with a

possible explanation for why we are able to be represent mental states, including our own, in the

way we are. I should stress, however, that this is aproposal, one based on substantial but

probative research from a wide range of fields, especially comparative ethology and

developmental psychology. I am following Bertrand Russells vision for philosophy: that it

should be comprehensive, and should be bold in suggesting hypotheses as to the universe which

science is not yet in a position to confirm or confute. But these should always be presentedashypotheses.

8As a hypothesis, my proposal for the evolution and development of free will

requires a number of assumptions.

2. Assumptions

Proposals for the evolution of cognitive abilities face several daunting problems. First of

all, despite the genetic and anatomical similarities between modern humans and our nearest

relatives (the common and bonobo chimps), humans have diverged significantly in certain

7 There is an important debate between theory theory of mind andsimulation theory of mind (see Carruthers andSmith, 1996), which I will discuss in section 5 below.

8From Bertrand Russells Logical Atomism (879). Wilfrid Sellars (1956) offers a myth about the development of

our abilities to understand others and our own mental states in terms of behavioral theories. His story might perhaps

be seen as an evolutionary account of theory of mind, though he presents it more as a cultural invention. My account

might be seen as offering the selective pressures that would lead our ancestors (like Sellars character Jones) to

develop a folk psychology.


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cognitive abilities, such as language, and in the anatomical feature that underlies cognition, the

brain. Numerous extinct ancestors in theAustrolopithicus andHomo lineages separate us from the

apes, and since cognitive abilities dont fossilize and since selective environments have changed,

we have limited resources to speculate about how our cognitive abilities evolved and why our

brains got so big. But we do have some resources.One resource is the comparative method. This involves looking at the traits of groups of

related living species and building common ancestors based on their shared traits, then assuming

any divergent traits evolved since the living species diverged from this common ancestor.9

The

traits that remain relatively unchanged in the living species (e.g. quadripedal locomotion in

monkeys) represent the ancestral trait, and the traits that changed (e.g. bipedalism in humans) are

the derived traits that evolved, perhaps by natural selection. This method provides a case for

evolutionary trends and selection for particular traits.

One particularly relevant evolutionary trend in primates is an increase in brain size

(specifically encephalization quotient [EQ], which is a measure of brain size relative to body

size).10

EQ, as well as brain complexity, increase from prosimians to monkeys to apes, with a

nearly threefold increase from chimpanzees through the extinct homo ancestors to modernhumans. And the comparative method suggests that the relations of ancestral to derived traits is

generally represented by the above ordering of families (prosimians to monkeys to apes to

humans); we can thus assume that higher EQ is a derived trait. Furthermore, given the significant

costs of big brains (in terms of energy use,11

difficulty of childbearing, and incapacity of infants),

there must have been a corresponding selective advantage to having relatively larger brains.12

Because big heads are not adaptive in themselves, primates increased brain size must allow for

behaviors which are advantageous in the particular selective environment in which they evolved.

These brain-based behaviors are cognitive abilities. The question, then, is which cognitive

abilities were selected for and what features of the environment selected for them.

It is highly unlikely that any single selective pressure drove increased EQ, because the

increases occurred at different times in a variety of environments. Furthermore, differentpressures may have been involved during speciation events than during more gradual changes

during the evolution of a species. Often, however, theories for increases in primate brain size and

cognition fall into two camps, one arguing that the increases were due to selective pressures from

a complex ecological environment and the other arguing that they were due to pressures from a

complex social environment. Drawing a sharp distinction between these two types of selective

9See Byrne (1995, especially ch. 2). Fossil evidence may help to confirm this assumption about the traits of the

ancestral common ancestors.

10Technically, encephalization quotient (EQ) is the ratio of an animals actual brain size to its expected brain size

based on its body size as compared to other species. EQ may also be measured more specifically to indicate the

relative size of the animals neocortex, thought to be the part of the brain most related to intelligence. Jerison (1973)presents the most detailed defense of the use of EQ as a measure of intelligence. He also argues that EQ corresponds

to extra neurons, beyond those needed to control bodily functions.

11The human brain, for instance, makes up two percent of our body mass yet uses 18 percent of our energy. Only the

liver and intestines are more costly. Presumably, energy costs translate to fitness costs.

12See Byrne (1995, 227-234).


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pressures surely oversimplifies the story, because, for instance, ecological and social

environments cannot always be clearly distinguished. It may be that the selective pressures from

different aspects of the environment were mutually reinforcing. For instance, selection for

frugivorous foraging may have led to an initial increase in brain size (in this case, for mapping and

remembering the locations of seasonal fruits), which in turn allowed for even larger brains(because of increased available energy in the form of fructose), and thus perhaps for increasingly

complex (e.g. larger) social groups; this social complexity may then have selected for further

increases in brain size.13

Nonetheless, my proposal generally sides with the social complexity theorists and focuses

on describing the aspects of the social environment that would select for particular cognitive

abilities. I will present arguments for why a particular type of environmenta complex social

setting including reciprocal altruismmay have selected for particular cognitive abilities that

presumably required larger (and more complex, interconnected) brains.

However, this claim raises another problem for any explanation of the evolution of

increased brain size and cognitive abilities. That is, which cognitive abilities were actually

selected for, thus leading to larger, more complex brains, and which abilities were, in turn, simplyallowed by larger, more complex brains? Which traits evolved because they increased relative

reproductive success (and hence are adaptations), and which traits are spandrels, non-adaptive

traits that arise as effects of adaptations?14

Humans use their big brains for all kinds of useful

things, like reading and writing, composing music and computing quadradic equations, but these

abilities are not adaptations; they do not exist because they increased reproductive success (in fact,

literacy is currently predictive of decreased reproductive rates). Rather, they are spandrels; they

are made possible by a large, flexible brain that was selected for other purposes.

My proposal attempts to avoid the problem posed by spandrels by looking for relatively

low-level cognitive abilities that are found, at least in rudimentary form, in primates, and that

develop relatively early in humans and without significant variation across cultures.15

Indeed,

there has been some cross-cultural research that shows similar trends in the order and timing of theonset of cognitive abilities associated with theory of mind.

16

My proposal relies on another important assumption: that the evolution of these cognitive

abilities parallels the developmentof the abilities in human children. I will discuss some of these

13See Milton, Foraging Behaviour and the Evolution of Primate Intelligence, in Byrne and Whiten (1988), and for

correlations between EQ and group size, see Dunbar (1988).

14See Gould and Lewontin (1978). These questions are problematic for any evolutionary explanation, but especially

for those involving phenotypic plasticity, such as increased brain size and complexity. Indeed, if variable

environments are what selects for phenotypic plasticity, then pinpointing the environmental factor becomes a moot

point, except if environmental variation itself can be described as a selective pressure (these issues may apply to

explanations for the evolution of sexual reproduction as well).

15 It would also help the proposal if these cognitive abilities evolved in distinct clades facing similar selective

pressures, suggesting convergent evolution. Indeed, there is some evidence that marine mammals, such as dolphins,

have evolved theory of mind abilities and exhibit reciprocal altruism. Dolphins also perform other behaviors

discussed in Figure 3, such as mirror-self recognition, pretend play, and language use.16

See, for instance, Astington (1993).


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parallels in theory of mind and deception in the following sections. Other abilities precede and are

perhaps necessary for theory of mind, such as imitation, pretend play, and mirror self-recognition.

These abilities follow a similar progression in both phylogeny and ontogeny (see Figure 3 below).

The argument, however, is not that ontogeny recapitulates phylogeny (in the sense suggested by

Haeckel). Instead, (following Piagets reasoning) it may be that a certain order in thedevelopment of some cognitive abilities is logical and natural, so that evolution may have

followed a similar course. As Andrew Whiten remarks, mindreading abilities are built up from

simpler precursors. . . . there may simply be logical reasons why step B precedes step C.17

The

basic idea is that the brain must be at a certain level of organization before it is able to

demonstrate certain abilities. In child development this organization arises as the brain grows and

increases in complexity (e.g. the development of folds, or gyri and sulci, in the cortex).18

In the

evolution of primates, increases in EQ represent not only increases in overall brain size but also in

neocortex size and in complexity, as measured by synaptic interconnectivity and folds in the

cortex.

The development and evolution of the brain may thus underlie the particular abilities

leading up to theory of mind. Specifically, it appears that apes, which show more evidence ofreciprocal altruism and deception than do other primates, also possess some levels of theory of

mind, whereas monkeys do not. Furthermore, one point at which the development of human

cognitive abilities diverges from those of apes is on tests for false-belief theory of mind. It may be

that this improvement in theory of mind, which is especially significant in deception and

detection, evolved in human ancestors and represents the key to our representational abilities. Let

us turn, then, to the theories and evidence supporting this account for the evolution of free will.

4. Reciprocal Altruism

Trivers defines altruism as behavior that benefits another organism, not closely related,

while being apparently detrimental to the organism performing the behavior.19

To explain how

such altruism between unrelated animals is possible, Trivers sets up the model for reciprocalaltruism: one animal,A, suffers a cost (in terms of reproductive success) by behaving in a way

that benefits another animal,B, but the cost toA is regained by a benefit received fromB at

some later time. Trivers definition has since been refined to differentiate it from byproduct

beneficence, pseudoreciprocity, and mutualism (e.g. many types of cooperative hunting). Unlike

these types of cooperative behavior, reciprocal altruism requires that the altruistic act is actually

costly at the time of the act and that it is separated from the reciprocal benefit by a significant

17Whiten (1991, 6). See also p. 277.

18See, for example, Restak (1986). An apparent problem for my proposal (raised by Steve Geisz) is that EQ actually

decreases in infants as they develop. This is because their body grows faster than their brains, which start off

disproportionately big. However, adult EQ is the measure used to compare phylogenetic differences, and in

development human brains do grow and become more complex (actually losing neurons while increasing synaptic

connections).

19Trivers (1971, 35).


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period of time.20

Significant delay is of course vague, but without this temporal element and the

absorption of cost by the altruist, reciprocal altruism would lose its significance for my proposal

since it would not set up the intense selective pressures for cheating. The type of social structure

that will most likely lead to deception and detection of deception involves long-term reciprocal

relations involving an exchange of various kinds of benefits.Are there any such social structures? It is difficult to ascertain. To test for reciprocal

altruism, ethologists must determine what counts as an altruistic act, assign to the act cost and

benefit values measured in terms of fitness, and then attempt to observe when such acts are

occurring, between whom, and with what values. This also requires knowing the relatedness of

the participants to differentiate it from kin altruism. Trivers own examples of cleaning symbiosis

and bird alarm calls do not seem to fit the refined model of reciprocal altruism. Cleaning

symbiosis is better viewed as byproduct beneficence between two species which have co-evolved

(like hosts and parasites). Bird alarm calls may not carry a cost to the caller, and even if they do,

they may be accounted for by kin altruism.

Trivers third example of humans is of course much more effective. He notes that all

human societies have the features his model predicts, such as long-term relationships betweenunrelated members, high mutual dependence, and food sharing. Furthermore, humans have

emotions that seem appropriate for maintaining reciprocity, such as trust, gratitude, and moralistic

aggression.21

The question is whether he is right that our reciprocal relations and their underlying

emotions are the result of natural selection, not simply a cultural invention. The similarities

between the systems of reciprocity, and especially of the corresponding emotions, across every

human society supports the claim that reciprocity has its roots in evolution. This claim would be

strengthened if our primate relatives demonstrated reciprocal altruism, which would suggest it

evolved in our common ancestors before the explosion of human culture.

Only a few examples of reciprocal altruism in animals have been well documented. The

best evidence so far is for vampire bats, some marine mammals, and some primates, especially

baboons and apes.22

Many primate social groups show signs of reciprocal relationships, such aslong-lasting relationships, many of which are between unrelated individuals, exchange of various

20See Taylor and McGuire (1988) and Mesterton-Gibbons and Dugatkin (1992). An analogy: byproduct beneficence

is to reciprocal altruism as safe driving is to polite driving. I drive safely for my own benefit and other drivers gain

the benefit of safety from my act, but if I let someone enter traffic at a busy intersection, I lose (a little) time perhaps

hoping the favor will be returned by someone in the future. The larger the social group (e.g. city), the less likely

drivers will be polite?

21As Robert Brandon points out, these emotions suggest that evolution played a role in human reciprocity, because, in

order to maintain itself, a culturally developed system would not require irrationally strong emotions, which are

sometimes disproportionate to the costs and benefits involved.

22See, for example, Taylor and McGuire (1988), de Waal and Luttrell (1988), and Rothstein (1988). Bats certainly do

not seem to demonstrate theory of mind or deception, but my proposal does not claim that reciprocal altruism will

necessarily select for these cognitive abilities; only that it is likely. With vampire bats, for instance, the difficulty of

their type of foraging may allow for group selection of reciprocity, but may make it difficult to cheat, since the

reciprocity involves regurgitating blood. Marine mammals may offer an example of convergent evolution following

the same progression of cognitive abilities as I am describing in primates (see note 15).


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benefits, such as food, alarm calls, fighting coalitions, and grooming, and the ability to recognize

individuals and their relationships to each other in familial and hierarchical groups. The

complicated fighting coalitions of baboons and the food sharing of chimpanzees offer numerous

and subtle opportunities for withholding reciprocity (fully or, more subtly, only in part). Thus,

reciprocal altruism may be rare, but it is likely our nearest relatives demonstrate it.The rarity of reciprocal altruism results from the obstacles it must overcome to become

stable in a population.23

Because of the time delay between altruistic acts, any population which

evolves altruistic behavior among non-kin could be easily invaded by cheats who receive benefits

while never returning them, at great cost to the sucker altruists. Thus, reciprocity would most

likely become an evolutionary stable strategy only in populations which could avoid invasion by

cheats, presumably by detecting them and withholding altruistic acts. But even if such detection

evolved, benefits remain for subtle cheats who return favors but find ways to receive more than

they give. Subtle cheating would not necessarily evolve in a society of reciprocal altruists

(nothing necessarily evolves), but it would offer a significant selective advantage if it did evolve.

Thus, as is the case with full-blooded cheats, subtle cheats could take over a population of naive

altruists and altruism would dissipate. To maintain reciprocity, a population needs to be able todetect subtle cheats, deny them benefits, and perhaps even punish them. So long as the system of

reciprocal exchange remains in place, however, there will be a selective advantage for increasing

subtlety. An animal that can avoid getting a reputation for cheating but can still get more than it

gives in a reciprocal exchange will reproduce more than its conspecifics.

Thus, reciprocal altruism offers an evolutionary paradox: while it allows for extensive

cooperation beyondspatially limited kin altruism and beyondtemporally limited mutualism,

reciprocity also selects for cheating, detection of cheating, and perhaps punishment for cheating.

In anthropomorphic terms, reciprocity allows the evolution not only of a communal marketplace

but also of embezzlement and castigation. It thereby provides selective pressure for a host of

cognitive abilities, beginning with the ability to recognize individuals as altruists and cheats, to

remember which is which, and to calculate costs and benefits given and received. Indeed,anthropologists often discuss the complicated reciprocal systems of human societies (e.g.

economies) in terms of the intelligence they require, but I suggest turning the equation around to

see whether reciprocal altruism selected for certain kinds of intelligence.

In addition to selecting for the cognitive abilities mentioned above, reciprocal altruism

may set up a feedback loop involving selective pressures for increasingly complicated deception

and then for increasingly effective detection of deception. This arms race could lead to the

evolution of the ability to recognize intentions, beginning with the abilities to associate certain

movements with future behavior (an understanding of agency), to recognize that the direction of

eye gaze indicates anothers perceptual information, and to inhibit acting on immediate

motivations, and perhaps culminating with theory of mind. Thus, we should look for evidence of

deception to see, first, whether such deception appears in primates, especially in their reciprocalexchanges, and then whether some forms of deception may involve theory of mind.

23Significant theoretical problems are also involved in explaining how reciprocal altruism could be introduced into a

population. Theories include group selection models and slow expansion of kin altruism to the larger group (see

respectively, Mesterton-Gibbons and Dugatkin [1992] and Rosthein [1988]).


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5. Deception

One who deceives will always find those who allow themselves to be deceived.

Machiavelli, The Prince

Though Machiavellis political commentary seems true enough, when examiningdeception in evolutionary terms, it would seem that selection would weed out those who allow

themselves to be deceived too often. Indeed, the selective advantage of deception seems

pervasive; as Dawkins and Krebs note, in animal communication the actor is selected to

manipulate the behavior of the reactor (1978: 383). But the pressure to counter this deception is

equally pervasive.

Deception, if defined simply as misrepresentation, may be completely hardwired (for

example, camouflage) or learned solely through reinforcement (by transferring a normal behavior

to a new, misleading context after being rewarded for performing the behavior in that context).

Deception at these levels occurs often both between species, powerfully selected for in the arms

race between predator and prey, andwithin species, for instance, during mating rituals. So, the

pressure to deceive and detect is pervasive among all creatures that perceive and react to eachother, but reciprocal altruism offers more numerous and more subtle opportunities to deceive.

24

The difficulty in determining how much of deceptive behavior is genetic and how much is

learned simply marks one example of a problem posed by most complex animal behavior. But

differentiating behavioristic deception from the next level, call it creative deception, is even

more difficult. Creative deception can be defined as acts by an agent deployedso thatthe target

is likely to misrepresent what the acts signify, to the advantage of the agent.25

Thus, creative

deception involves deliberate misrepresentation; while the goals sought may be due to

behavioristic reinforcement, the deceptive means used to attain these goals are the result not

simply of past reinforcement but of prediction about others behavior.

Testing for such creative deception is notoriously difficult. Most significantly, the

researcher must try to determine that the deceptive tactic is notthe result of prior reinforcement, abehavior learned by trial and error (even if only one trial). Furthermore, if the deception is

creative, its goal is to be difficult to detect, so, even a higher primatethe primatologistmay

miss it.26

Creative deception is difficult to test for in experimental set-ups, and examples in the

wild will appear anecdotal. Andrew Whiten and Richard Byrne (1988) attempted to overcome

these problems by gathering anecdotal and experimental evidence of deception from a wide

variety of researchers. They then tried to determine whether the reports of deception involved a

target acting on a false belief and also whether the agent intentionally caused that false belief.

The latter, of course, is the hardest evidence to ascertain (especially without language) and

also the most significant aspect for my proposal; determining whether an animal can differentiate

24 Since reciprocity occurs between conspecifics (creatures that behave in similar ways), it also encourages inferringothers behavior from your own, perhaps even simulating how you would behave given a particular situation. Rather

than conflicting, simulation theory of mind may be a precursor for theory theory of mind.25

This definition is only slightly modified from Whiten and Byrnes definition of tactical deception (1988). See

also Guzeldere, Nahmias, and Deaner (forthcoming in The Cognitive Animal, MIT Press).

26Creative deception should also be relatively rare, since targets will try to detect and avoid it. As Samuel Butler

wrote, The best liar is he who makes the smallest amount of lying go the longest way.


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between knowing thata deceptive act works and knowing how it works is the key to determining

if the animal is representing mental states in a way that suggests theory of mind. While there has

been no conclusive evidence for such high-level intentionality, involving the agents knowing how

it is manipulating the targets beliefs, Whiten suggests that chimpanzees offer the strongest

indications that an agent entertains some concept of deception itself, distinguishing between overtbehavior and the deceptive intentions that sometimes underlie it (1991: 276).

Indeed, Whiten and Byrne received the most submissions for creative deception in

chimpanzees and other apes and few submissions for prosimians and non-primates. They classify

most monkey deception as less creative than apes, except for baboons, which, consistent with this

proposal, also have high EQ and whose fighting alliances seem to involve reciprocal altruism.

Whiten and Byrnes findings have been questioned both because they often rely on anecdotal

evidence (as one critic said, the plural of anecdote is not data) and because, some critics claim,

most of the examples still fall to Lloyd Morgans canon and can be explained with a behaviorist

interpretation, albeit a complicated one.27

Nonetheless, their survey, as well as more recent

experiments, indicate that apes are able to inhibit their normal behavior (e.g. their motivation to

move towards food) because they recognize how a conspecific (or sometimes a human trainer)will behave based on their current behavior. They recognize that certain animals are agents in the

world which, unlike objects, act based on their perceptions and desires, and in light of that

understanding, they control their normal behavior (e.g. to move towards food).

A commonly cited example of such deception involves a subordinate chimp, Belle, who

has been shown the location of some hidden fruit which the dominant chimp, Rock, would takes

from her if he had access to it. When released with Rock, Belle either avoids the hidden fruit until

Rock is preoccupied or leads the group away from the food. The situation escalates to the point

where Belle leads the group to the wrong site or the site of a smaller food cache, but Rock then

counters by pretending to be preoccupied, only to follow Belle to the right location. Belle inhibits

her normal behavior of moving immediately to the food source; Rock inhibits his behavior of

attending to anothers movement towards food. And both apes seem to recognize how their ownand the others behavior (e.g. body orientation and eye gaze) indicate future behavior.

28

Other examples of deception cited by Whiten and Byrne include apes and baboons (1)

pretending to be injured to avoid confrontations, (2) covering up sexually induced outbursts to

avoid angering a dominant, (3) hiding fear grins in conflicts, and (4) pretending to see predators to

escape pursuit.29

If specific past reinforcement can be ruled out, these examples indicate that the

agent recognizes that the target has a desire and will act on it, but that certain behavior (often the

inhibition of normal behavior) may prevent the target from acting. This behavior often includes

the agents concealing (as in 2 and 3 above), distracting (as in 1 and Belles false leads), or

creating a false image (as in 4).

Furthermore, apes offer the best evidence for detection of deception, as in the cases where

the target pretends be preoccupied and also in cases where apes become angry when they have

27See Commentary on Whiten and Byrne (1988). The quotation is from Irwin Bernstein, 247.

28This experiment was run by Charles Menzel (see Byrne, 1995: 132). A similar experiment was run on ring-tailed

lemurs (prosimians) by Rob Deaner at Duke University. He found no evidence of intentional deception.

29See Whiten and Byrne (1988) for more examples of deception.


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juice as opposed to one who intentionally spilled it.32

Apes, however, have not shown evidence of

false-belief theory of mind.

Children pass desire theory of mind tasks beginning around age two. These tasks often

involve asking the child what a character will do next given his prior behavior towards a goal (like

the tests on the chimp, Sarah), or whether a character in a story will be happy if he finds a desiredobject. However, children do not pass belief tasks until age three. For example, some tests ask a

child where a character will look for an object, given what the child and the character know about

a situation (e.g. the child is told there are bananas in the cupboard and in the refrigerator; Joe

knows there are bananas in the refrigerator; where will Joe look for bananas?).

False-belief theory of mind, however, is not acquired until around age four. It indicates an

ability to represent a situation which does not correlate with reality and to represent anothers

beliefs as distinct from ones own. For example, if the child sees Joe find bananas in the

refrigerator, but then sees Joes mom move them to the cupboard while Joe is gone, where will the

child say Joe will look for the bananas when he returns? Most three years olds will say Joe will

look in the cupboard, because they assume others beliefs are the same as their own. But four year

olds can representas distinct from the actual situation and their own beliefsJoes false beliefabout the items location, so they say Joe will look where he believes the bananas are, not where

they actually are.

Another test involves asking a child what she thinks will be in a pack of M&Ms. After

she responds, M&Ms, she is shown that the pack actually contains coins. When she is asked

what another child (new to the scene) will say when asked what the pack of M&Ms contains,

most three year olds will answer coins, demonstrating their inability to distinguish their own

knowledge about the world from others knowledge of the world. Four year olds pass the test.33

They recognize that they have apoint of view that is distinct from others view of the world,

developing an understanding of subjectivity, an understanding that perhaps begins with the

infants distinction between the part of the world she controls (e.g. her limbs) and the rest of the

world.34

Josef Perner also offers evidence that children at age four begin to perform what he calls

genuine deception, manipulating others in order to induce in them false beliefs about reality. In

addition to experiments that test for such deception, the well-worn intuitions of mothers and

teachers confirms it: most of them report that children begin telling deliberate lies around the age

of four.35

Indeed, Perner and some other developmental psychologists believe that such deception

32These tests were devised by Daniel Povinelli (reported in Byrne 1995).

33Surprisingly, when asked what they had earlier believed was in the pack of M&Ms, the children will also answer

coins (and they are not lying to cover up for their mistake). See, for example, Wellman (1990) and Perner (1991)for descriptions of these experiments.

34Piaget recognized the significance of the limits of the infants will in the development of their understanding of

subjectivity and objectivity.

35Perner (1991, 189-202).


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requires the representational abilities involved in false-belief theory of mind. Increasingly

complex theory of mind certainly seems to allow for more complex types of deception.

For instance, desire theory of mind allows an individualA to predictBs behavior based on

his desires or goals. So, for instance, ifA knowsB wants her bananas and will try to take them,

she may inhibit her own desire to take them out and eat them while he is around. But belief theoryof mind would allowA to predictBs behavior based on what he has seen (an important aspect of

understanding belief is connecting seeing with knowing). So, for instance,A could turn her back

fromB while she eats her bananas. Such behavior is similar to the concealment involved in some

primate deception. But false-belief theory of mind seems to exponentially increase the

possibilities for creative deception. It allowsA to recognize whenB is ignorant, to try to keep him

ignorant, and to try to change his beliefs to her advantage. For instance,A might give a false

alarm call to makeB leave so she can eat her bananas in peace. Children with language and false-

belief theory of mind can tell lies in order to make their targets believe what is not the case.

Children become better liars as they recognize the many factors that may influence others beliefs

(e.g. they learn that saying they did not eat the cookies may not work if they have crumbs on their

face).Thus, there seems to be distinctions between desire, belief, and false-belief theory of mind

which underlie varying competencies in deception. However, delineating sharply between the

three levels of theory of mind may be painting too simplistic a picture. For instance, some

researchers believe it is impossible to have belief theory of mind without some understanding of

false belief.36

A more substantial debate involves delineating between theory of mind and

simulation. Theory theory suggests that our mind-reading abilities rest on our ability to

recognize patterns of behavior and organize them under theoretical mental constructs (like beliefs

and desires), which we then apply to our own mental states (notice the similarities between this

view and the view of social psychologists discussed in Chapter 3). Simulation theory suggests

that we understand others mental states by imagining how we would feel and how we would

behave in a situation like the one they are ini.e. simulating anothers point of view.37

I am notconvinced the difference between these two views is as significant as the debate implies. In fact, I

believe simulation likely provides a building block for theory of mind, and even adults seem to

use both inferential methods depending on the type and complexity of the situation (we may

simulate to understand another persons emotional statefor instance, we feel sad when we see

bad things happen to movie charactersbut we likely use theory of mind to predict others

complex behaviorfor instance, we try to get in the head of the Godfather to figure out what he

will do next). In any case, I will not try to adjudicate these particular debates, as I do not believe

their outcome substantially affects my proposal.

Some researchers have also questioned whether theory of mind requires language. As P.K.

Smith writes, Only if chimpanzees could talk to each other about mental states would they have

evolved mind reading, and only if they could talk to us about mental states would we believe

36See, for instance, Harris chapter in Carruthers and Smith (1996).

37Carruthers and Smith (1996) contains several chapters dealing with this controversy.


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them.38

And Donald Davidson offers a priori arguments for a related point in Rational

Animals (1982): First, I argue that in order to have a belief, it is necessary to have the concept

of belief. Second, I argue that in order to have the concept of belief one must have language

(478).39

Indeed, there is a long tradition in philosophy, going back to Descartes, that views

language as uniquely human and as necessary for rational thinking, perhaps even consciousness.While language certainly makes it easier to test for theory of mind and surely increases the

breadth of our mental states, I am inclined to agree with those researchers who turn the equation

around to suggest that representational abilities like those involved in theory of mind underlie the

evolution and development of language. Merlin Donald, for instance, writes that prior to the

evolution of a system as revolutionary as human language, the cognitive stage had to be set

(1991: 164), and this stage involved mimetic and representational abilities found in apes and pre-

linguistic human ancestors. Richard Byrne claims with even more vigor: The ability to imagine

other mental viewpoints is a necessary precursor to language, and it certainly evolved first (1995:

233). This controversy will require much more research, but my proposal suggests that theory of

mind is possible without language (e.g. in apes) and may even be a step in the evolution of

linguistic abilities.It seems that the ability to represent states of affairs that do not exist is crucial to the

symbolic aspect of languagedistinguishing symbols from the objects they representand that

the ability to represent others mental states is crucial to the conversational aspect of language

understanding, for instance, that you do not know what I know when I inform you of what I know.

Some researchers (such as Donald) have further suggested that mimetic culture, teaching, and

even some human technology could not develop without these representational abilities. The idea

behind these suggestions is that theory of mind involves representing ones own and others

mental states. This ability may have been the adaptation which in turn underlies many exaptations

and spandrels that require a similar sort of representational ability.40

This includes, I believe, the cognitive abilities I have identified with free will. In

introspecting on our conflicting motivational states, we must be able to represent them asmotivational states and understand their relation to actions and the world. Furthermore, the ability

to distinguish between belief and reality allows us to imagine various possible futures and

consider how our motivations may influence which of them occurs. Indeed, it is difficult to

imagine how the activity of deliberation would be possible without representing at least two

possible alternatives for the future. More generally, theory of mind seems to underlie self-

conscious knowledge, and as I have suggested, such knowledge is the basis of free will.

38In Carruthers and Smith (1996, 354).

39Davidsons argument faces a possible counterexample from autistics. Autistics lack theory of mind abilities but

they possess language and the concept of belief.

40There is a significant debate about whether theory of mind is a modular (domain-specific) ability or a general

(central) processing ability, the main evidence for the former coming from autistics who seem to have a specific

deficit in theory of mind which might be caused by damage to a specific part of the brain. It may seem that if theory

of mind is a module, it more likely evolved by natural selection, as evolutionary psychologists would suggest.

However, if theory of mind represents an advancement of already-present general processing abilities, it may still

have evolved by natural selection. So, I am not concerned about the effect of this debate on my proposal.


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6. Conclusion: Do Chimps Have Free Will?

Though the precise interpretation of theory of mind still needs refinement, the evidence so

far supports differences between desire, belief, and false-belief theory of mind based on age of

onset in children. These differences correlate not only with a developmental sequence in children

but also with the phylogenetic sequence from monkeys to apes to humans, suggesting a particularordering of cognitive skills in both evolution and development. I have suggested that this

progression was driven by the social complexity involved in some primate societies, especially

those that include reciprocal altruism, and by the resulting selective pressures to deceive and

detect deception. The great apes, especially chimps, have shown evidence of reciprocity and

intentional deception. In addition, they have demonstrated the abilities to follow others eye gaze,

imitate others, predict others behavior based on their desires, and take account of others

ignorance (e.g. in deception and teaching). They also pass mirror self-recognition tests and can be

taught symbolic language and self-reference.41

In sum, apes appear to have at least the rudiments

of an understanding of their own and others mental states.

Does this mean that they can introspect on their motivational states, identify which of them

they prefer to move them, and influence their motivations accordingly? Do chimps have free will?Probably not, but this question need not be answered with a resounding no. Since an agent

possesses free will to the degree that she possesses the requisite cognitive abilities to know

herself, we can say that chimps may possess some degree of free willthey may at least be able to

inhibit immediate (first-order) motivations in order to achieve goal they recognize as more

important. To many, it may sound counterintuitive to suggest that any animal has any degree of

free willwe generally consider free will unique to humans. But consider how we would answer

the question of whether a 4-year-old child has free willor perhaps an 8-year-old or a 13-year-

old. We accept that children have varying degrees of free will and responsibility according to the

degree to which they can know what they are doing and control themselves accordingly. Despite

most cultures coming-of-age ceremonies, we do not believe children go from lacking free will to

having it overnight, nor do we treat them that way.However, an important difference between chimps and children is that children not only

develop their self-knowledge and self-control as they mature, they also grow up learning the moral

values of their culture. So, the degree to which they possess free will increases at the same time as

they learn to exercise those abilities specifically in terms of their cultures specific moral

obligations. That is, as they acquire the ability to act in accord with their knowledge of

themselves and the world, they acquire the relevant knowledge of the values in terms of which

their actions will be judged by others in their culture. Children, as they grow up, gain

responsibility as well as free will.

Furthermore, children learn language, which, as I mentioned above, surely increases their

ability to conceptualize their desires and contrastively compare them.42

But some chimps (and

other apes) have been raised within a human family and trained to use sign language (or someother symbolic language). Not surprisingly, their human trainers anthropomorphize them, and this

includes treating them as responsible for some of their behavior. The human parents see the

41See Figure 3. See also Byrne (1995: 224).

42See Taylor (1977).


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chimps as able to manipulate and deceive, and they blame the chimps for breaking rules when they

should have known better.43

These parents take rudimentary reactive attidudes towards their

ape charges in the same way other parents do. Compare Peter Strawsons point about how we

move from the objective attitude to the reactive attitudes in our relationships with children:

Thus parents and others concerned with the care and upbringing of children cannot have totheir charges either kind of attitude [objective or reactive] in a pure or unqualified form.

They are dealing with creatures who are potentially and increasingly capable both of

holding, and being objects of, the full range of human and moral attitudes, but are not yet

truly capable of either. (1962: 75).

We gradually grow into free and responsible creatures. But, I would suggest, the development of

free will is tied more closely to our evolutionary and genetic heritage, while the development of

moral responsibility is tied more closely to our maturation within a particular culture with its

particular set of moral obligations. Free will involves cognitiveprocesses that we develop given

any normal upbringing; moral responsibility involves specific contentrelative to our particular

upbringing.Nonetheless, like any other cognitive ability, free will may be developed and improved. In

addition to learning the content of our culture and hence increasing our ability to act responsibly,

we can learn how to improve our ability to consider our motivations rather than acting on them

without thinking. We can learn to know ourselves better. And most significantly, we can learn

techniques of self-control and strength of will so that we can more effectively act on our self-

knowledge. Moral education and experience increases moral responsibility. Practical education

and experience increases free will.

There are limits to how much a chimp can develop its free will. There are also limits to

how much we can develop our free will. Much of who we are is given, and our reflective

knowledge and self-control works within boundaries, those that apply to all of us because of our

human nature and those that apply to each of us because of our individual history. But within anyboundaries there are degrees of freedom. The more we know, the more we can move within those

boundaries and perhaps even push them back. Knowledge is power.

43Accounts from these human trainers are filled with the language of relationships and responsibility. For instance,

Roger Fouts writes of new volunteers to care for his chimp, Washoe: [They] left their chimp myths behind and

built respectful relationships with the individual members of Washoes family. They were rewarded with one thing

only: chimpanzee friendship (1997: 291). Of course, many of us take similar attitudes towards our pets, and we are

likely making a mistake if we really endow them with free will and responsibility. But when it comes time to

punishing them, we usually recognize that they couldnt help it precisely because we believe they either didnt

know any better or didnt know how to control themselves.


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appendix nahmias

Documents