REVIEW
Evaluating social contract theory in the light of
evolutionary social science
Paul Seabright
1,2
* , Jonathan Stieglitz
2
and Karine Van der Straeten
1,2
1
Toulouse School of Economics, University of Toulouse Capitole, Toulouse, France and
2
Institute for Advanced Study in
Toulouse, University of Toulouse Capitole, Toulouse, France
*Author for correspondence: Paul Seabright, Toulouse School of Economics / IAST1, Esplanade de l’Université, 31080
Toulouse Cedex 06, France. E-mail: [email protected]
Abstract
Political philosophers have long drawn explicitly or implicitly on claims about the ways in which human
behaviour is shaped by interactions within society. These claims have usually been based on introspection,
anecdotes or casual empiricism, but recent empirical research has informed a number of early views about
human nature. We focus here on five components of such views: (1) what motivates human beings; (2)
what constraints our natural and social environments impose upon us; (3) what kind of society emerges as
a result; (4) what constitutes a fulfilling life; and (5) what collective solutions can improve the outcome.
We examine social contract theory as developed by some early influential political philosophers (Hobbes,
Locke and Rousseau), who viewed the social contract as a device to compare the ‘natural’ state of humans
with their behaviour in society. We examine their views in the light of recent cross-cultural empirical
research in the evolutionary social sciences. We conclude that social contract theorists severely underes-
timated human behavioural complexity in societies lacking formal institutions. Had these theorists been
more informed about the structure and function of social arrangements in small-scale societies, they
might have significantly altered their views about the design and enforcement of social contracts.
Keywords: Political philosophy; small-scale societies; social contract; Hobbes; Locke; Rousseau; Darwin
Social media summary: Social contract philosophers overlooked the central role of informal social
institutions in governing human behavior.
1. The implicit empirical underpinnings of political philosophy
1.1. Empirical claims abou t human society
From its earliest beginnings, political and social philosophy has been not only conceptual but also empirical,
albeit at a very general level. This is true not only of those usually considered political philosophers (such as
Plato, Aristotle, Confucius, Machiavelli, Hobbes, Locke, Voltaire, Montesquieu, Rousseau, Hume and Mill),
but also and especially of sociologists, economists, historians and essayists such as Herodotus, Thucydides,
Ibn Khaldun, Montaigne, Gibbon, Smith, Malthus, Ricardo, Marshall and Weber, all of whom made
contributions that have had a lasting impact on political philosophy, broadly considered.
Such writers as these have expressed their opinions about the facts of at least five main matters,
namely:
1. What motivates human beings – what makes us think and behave the way we do?
2. What constraints our natural and social environments impose upon us?
3. What kind of society emerges as a result?
© The Author(s), 2021. Published by Cambridge University Press on behalf of Evolutionary Human Sciences. This is an Open Access article,
distributed under the terms of the Creative Commons Attribution lice nce (http://creativecommons.org/licenses/by/4.0/), which permits unre-
stricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.
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4. What is ‘good’ for human beings, in the sense of constituting a fulfilling life, whether or not we
are aware of it?
5. What collective solutions might be found to improve the outcome.
For the purposes of this paper, we will refer to each set of views about these five matters as ‘a theory
of human nature’. Although these views contain inescapable elements of value judgement, they are
also grounded in broadly empirical claims about what human beings and their societies are like.
While this framing does not necessarily correspond to how political philosophers have expressed
themselves, it provides a general conceptual framework that can be empirically evaluated, and it shares
core features with frameworks of evolutionary social scientists including Darwin. When Aristotle
wrote ‘Man is a political animal’ (Zoon Politikon), did he mean that man is motivated by political
aims, or that a life of political action is the only worthwhile life for man? Probably he meant both.
However, like many other political philosophers, he developed his views on the basis of generalisations
from his own and others’ observations.
So did Hobbes, when he claimed that the life of man in the state of nature was ‘solitary, poor, nasty,
brutish and short’ (in Leviathan, Part 1, Chapter 13), or Rousseau, when he claimed that ‘man is born
free, and he is everywhere in chains’ (in the opening sentence of On the social contract). Our conten-
tion in this paper is that it is time to update many of these generalisations from observation in the light
of more recent empirical research, beginning with Darwin (1871). We do not aim to provide a system-
atic, let alone exhaustive, review; instead we select a few illustrative generalisations that have pro-
foundly influenced contemporary academic and public discourse on political philosophy, and for
which sufficient research within the evolutionary social sciences exists to assess their empirical validity.
In writing thus of ‘generalisations from observation’ we do not mean to imply that political
philosophers have been innocent empiricists whose only shortcomings are due to their having lived
before the publication of the latest high-quality scientific research. Quite the contrary: many political
philosophers have been engaged in consciously partisan, even propagandist projects. Some have been
tutors or counsellors to political rulers – most famously Aristotle, who was tutor to the future
Alexander the Great, and Thomas Hobbes, who was tutor to the future King Charles II (who later
helped shield his former tutor from charges of atheism). Many others, including Ibn Khaldun,
Niccolo Machiavelli, John Locke and Adam Smith, have enjoyed enough social proximity to those
wielding political power for us to be wary of considering their theories to be free of partisan intent.
Note that Machiavelli himself was well aware of this fact, and writes: ‘The prejudice which is entertained
against the people arises from this, that any man may speak ill of them openly and fearlessly, even when
the government is in their hands; whereas princes are always spoken of with a thousand reserves and a
constant eye to consequences’ (Discourses on the first decade of Titus Livius, Book 1, Chapter 57).
Arguably one of the strongest arguments for the existence of universities is to make scholars less directly
dependent on the favour of rulers whose propagandists they may be tempted to become.
Even without personal incentives to argue for specific political arrangements, philosophers have been
profoundly influenced by the economic and social circumstances in which they lived, to the point where
their taking a certain view on human nature or the nature of society may be at least as fruitfully illu-
minated by these circumstances as by the evidence available to them at the time. That this is now a
truism owes a great deal to the influence of historians of political thought such as Quentin Skinner
and the Cambridge School (Skinner, 1969). Our purpose here is in no way to downplay these economic
or social influences, nor to indulge in pointless counterfactual speculation about what Aristotle might
have argued if only he had had advance access to Nature or Evolutionary Human Sciences.
Nevertheless, among the reasons why the works of such political philosophers have had such per-
suasive force over the centuries has been that they are considered to embody fundamental views about
the nature of human beings and their place in society that appeal to diverse readers. Keynes’s remark
on the last page of The general theory that ‘Practical men who believe themselves to be quite exempt
from any intellectual influence, are usually the slaves of some defunct economi st’ (Keynes, 1936) can
be applied with even greater vigour to defunct political philosophers, who may exert an
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unacknowledged influence on views about human nature and society that deserve to be openly exam-
ined and reviewed.
A particularly well known example is the tabula rasa theory of the human mind, which dates back
at least to Aristotle’s De Anima, but is best known today through the writings of John Locke (1689a).
The theory has been sufficiently influential that Steven Pinker devoted an entire book to demolishing
it (Pinker, 2002) and both Locke and Pinker are widely cited today in the literature on individual and
social learning.
It may matter less whether views such as these are accurately attributed to the authors concerned,
and still less whether modern readers understand why they were adopted in the first place. Such views
can be assessed against later available evidence, even if we accept that the factors that may have con-
tributed to their development and propagation are rarely reducible to empirical conviction alone.
We have a specific reason for evaluating select empirical content relevant to matters 1–5 above.
These matters correspond to a way of analysing social processes that has been used fruitfully within
a number of social sciences, and which we can call equilibrium analysis. It has been most explicitly
deployed in economics but is also used in political science, evolutionary anthropology and biology,
as well as some parts of quantitative sociology and economic history. Its strength consists in allowing
the facts under 1 and 2 to explain the outcomes 3, which can be compared against the standard of
evaluation 4. Proposals for improved outcomes 5 then have to be checked for consistency with 1
and 2 and shown to be feasible in spite of the actual tendency of society to produce inferior outcomes
3. Outcomes 3 represent equilibria of the social processes characterised by 1 and 2, and the alternative
outcomes 5 have to be possible equilibria as well. The word ‘equilibrium’ is not always used explicitly
in such analysis, so it is worth defining explicitly.
An equilibrium is a state of society which, given the motivations and constraints of its members,
would tend to persist in the absence of some external disturbance. Note that an equilibrium is not
necessarily a desirable outcome under any reasonable criterion: indeed perhaps the most famous
description of a political equilibrium is George Orwell’s horrifying injunction in his novel 1984 to
‘imagine a boot stamping on a human face, forever’. Yet there is an important reason for focusing
on equilibria: if we try to implement political solutions that are not equilibria, they will not last.
1.2. The interest of the social contract approach
The range of possible political philosophers we might have chosen to cover is vast. For this paper we
draw examples from three thinkers (Hobbes, Locke and Rousseau) who developed a ‘social contract’
approach to political philosophy. Our aim here is certainly not to propose a synthetic summary of
their philosophical thought, but simply to give our subjective interpretation of an illustrative subset
of their ideas about human nature.
These three writers articulated with particular clarity a distinction between attributes of human
motivation and behaviour in the ‘state of nature’ vs. those that were the products of society with formal
institutions. By ‘formal institutions’ we refer to those created by humans to govern human behaviour;
they comprise written guidelines (e.g. laws, charters, constitutions) that are enforced by authorities.
This distinction between humans in the state of nature and in society with formal institutions was rad-
ically novel in the history of political thought, but has remained an important part of our thinking
about human behaviour ever since.
Whether we look at ancient thinkers such as Aristotle or Confucius, or more modern ones such as
Marsilius of Padua or Machiavelli, before the writings of the social contract theorists humans were
unimaginable as abstracted from society. For Confucius, for example, humans are inextricably embed-
ded in a network of social relationships, which define who they are as well as their duties and moral
obligations. For Machiavelli, ever-changing relations of power, submission and subjugation between
individuals are among the defining features of life in society. For both of them, there would be no
point in thinking about humans in isolation, independently of the social and political context in
which they live.
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This means that, in examining the work of these thinkers, we will distinguish under item 3 between
the kind of society which emerges when human beings interact in a state of nature, and that which
emerges in a modern socie ty with formal institutions. These thinkers drew wildly different conclusions
from this contrast; for Hobbes, the state of nature involved such fear and potential for violence that
even the institutions of a repressive monarchy were much to be preferred, while for Rousseau the insti-
tutions of modern society (and notably those of private property) were responsible for far greater evils
than any in a state of nature. Neither author explicitly used the notion of equilibrium that we described
above, but for both of them the underlying idea is there. Societies are the outcome of social processes
resulting from the interaction of people who have certain characteristics; if we want to work for better
outcomes we should forget about trying to change human nature, and concentrate instead on chan-
ging the conditions under which people interact.
This should clarify why we focus on empirical evidence from small-scale societies. Compared with
industrialised and agricultural societies, small-scale societies – including foragers, horticulturalists,
pastoralists and subsistence-level societies with mixed economies (e.g. forager–horticulturalists) – pos-
sess more similar social and ecological features that were typical of more than 99% of the evolutionary
history of the genus Homo (prior to the first agricultural revolution around 12,000 years ago). These
features include: subsistence lifestyle characterised by minimal technology; limited energy availability
(a high physical activity level relative to consumption); limited material wealth; high fertility; frequent
resource pooling within residential settlements; and an absence of formal institutions.
We acknowledge that the term ‘small-scale societies’ is inadequate to capture the range of variation
in production technology, social organisation and hierarchy, demography, responses to external social
processes and other features characterising both contemporary and past human societies
(Reyes-Garcia et al., 2017). Indeed, under certain ecological conditions, foragers are known to have
been relatively sedentary, produced food surpluses which were stored, been territorial, owned property
and had marked status differentials (Rowley-Conwy, 2001).
Nevertheless, for our present purposes we can say that small-scale societies illustrate one kind of equi-
librium in which humans may find themselves, and large-scale societies illustrate another. The contrast
between the two may illuminate what difference formal institutions can make. However, whereas evi-
dence from large-scale modern societies is everywhere around us, evidence from small-scale societies
has been much less easily available, and thus lends itself more to inaccurate characterisation.
We have two reasons for focusing on small-scale societies, and neither depends on claiming that
the thinkers we examine believed that a state of nature had ever really existed. The first reason,
which is not really controversial, is that these are the only observable instances available of human
societies that function without formal institutions, which is the closest set of real conditions to
those which the social contract theorists had in mind. The second, which is much more controversial,
is that many of the conditions of small-scale societies have persisted since the origin of modern
humans, constituting a physical and social environment against which humans have been evolving
under the influence of both natural and cultural selection. To the extent that there are common fea-
tures of psychology and behaviour in such societies, they may come closest to constituting a ‘human
nature’ that can be compared with the human nature to which our various philosophers appealed.
Finally, a word about Darwin. As is well known, Darwin avoided addressing questions about
human evolution in The origin of species, not because he believed them to be unimportant, but because
he was afraid that controversy over the social, political and theological implications of his theory of
evolution by natural selection might impede the scientific evaluation of the theory itself. By the
time he came to write The descent of man he had realised that such controversy was unavoidable
and was better addressed directly. In the latter book he made very clear that natural selection had
shaped not only human morphology but also human behaviour, and the subsequent century and a
half has shown what a powerful insight that was.
For much of the twentieth century, unfortunately, explanations of human behaviour in terms of
environmental factors were considered substitutes for rather than complements to explanations drawing
on natural selection, and this undoubtedly explains why political philosophy has not made more explicit
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use of the insights of the Darwinian approach. It is now much easier to accept that humans are flexible
learners who are massively influenced by signals from their natural and social environments because
natural selection has shaped them to be this way. The work of Robert Boyd and Peter Richerson has
been particularly influential in this regard – see Boyd and Richerson (1985) and Richerson and Boyd
(2005). In this spirit we hope that an attempt to draw out some implications for political philosophy
from empirical research in evolutionary social science, in particular cross-cultural human behavioural
variation, is an appropriate tribute to The descent of man on the 150th anniversary of its publication.
We structure this paper as follows. In Section 2, we set out the views of the three social contract
theorists about the five main matters of political philosophy we outlined above. In Section 3 we sum-
marise the ways in which recent research in evolutionary social science can cast light on these views.
Section 4 answers some general questions about how the circumstances of the state of nature should be
interpreted. In Section 5 we briefly summarise and conclude.
2. The social contract theorists
2.1. Common features of the social contract
While there are many differences between the social contract theorists, we begin by focusing on their
commonalities. This can best be characterised as an attempt to establish the principles of legitimate
political power through a rational and materialistic approach. Importantly for our purpose, these
philosophers explicitly base their system on some description of human nature, as emphasised in
the concept of a ‘state of nature’. The root of their philosophical system is in a sense anthropological.
The purpose of this exercise is to seek a basis of power that is less debatable than divine law, and less
arbitrary than the simple use of force. To do so these theorists turn to the legal concept of contractual agree-
ment based on mutual consent. The idea of the contract is clearly borrowed from law. From the Latin ‘soci-
etas’, the word ‘society’ originally refers to a contract whereby individuals pool property and activities, and
in which the partners undertake to share any loss or benefit that may arise from this association.
The fundamental shared concepts of social contract theorists include the state of nature, and two
types of contracts, those of association and of government:
• The state of nature – the state of humans having no other bond between them than their com-
mon quality of being human. Different thinkers hold different views as to what other qualities
were associated with this state; although all thought of humans in this state as ‘equal’ in some
respects, the character of this equality differed substantially.
• The ‘contract of association’–the contract of individuals among themselves when they decide to
unite to confer on a single person or an assembly the task of making decisions in such a way that
these decisions are considered to be the will of all.
• The ‘government contract’–the voluntary surrender of some individual liberty and the promise
to obey the government.
Social contract theories differ according to their conception of the state of nature and their analysis of
the two contracts. Importantly, they all share a similar methodology: start from a description of
human nature (as perceived to be real, or abstractly in the state of nature), and derive from these foun-
dations, in a deductive way, the principles of legitimate political power. All were inspired by natural
sciences and mathematics (in particular Hobbes by geometry and Rousseau by chemistry).
In addition to a conscious distancing from scholasticism and from religious justifications for pol-
itical legitimacy, social contract theories also broke with ancient philosophy and in particular with
Aristotle’s Politics, which established social organisation on moral principles and on natural rights
that existed prior to formal societal institutions. For these social contract theorists it is not true
that ‘man is by nature a political animal’. Man becomes social only by his own will. The city-state
does not exist by nature, but results from a convention.
We now look at ways in which the details of the social contract theories varied between thinkers.
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2.2. Hobbes
Instead of starting from a (claimed) revealed truth, Hobbes bases his social contract theory on his con-
ception of human nature, in one of the first attempts at the secularisation of political thought. In
Leviathan (published in 1651), Hobbes advances several claims:
• man in the state of nature is fundamentally fearful and driven by passions;
• individuals are fundamentally equal;
• for fear of violence, they will willingly abdicate their right of nature in favour of an absolute sov-
ereign who will guarantee public peace using the power of repression at his disposal.
In terms of the five matters we outline above, the Hobbesian view of human nature is that:
1. Humans in the state of nature seek only to ensure their own preservation, by all means, and are
driven by passion, particularly for power (‘in the first place, I put for a general inclination of all
mankind a perpetual and restless desire of power after power, that ceases only in death’; chap.
XI). Moreover, men are essentially equal in strength and capacity (‘Nature hath made men so
equal in the faculties of body and mind as that, though there be found one man sometimes
manifestly stronger in body or of quicker mind than another, yet when all is reckoned together
the difference between man and man is not so considerable as that one man can thereupon
claim to himself any benefit to which another may not pretend as well as he. For as to the
strength of body, the weakest has strength enough to kill the strongest, either by secret machin-
ation or by confederacy with others that are in the same danger with himself’; chap. XIII).
2. The main constraint on individuals is the capacity of others to inflict violence on them. In con-
trast, they are not constrained in their ability to inflict violence on others. Hobbes considers that
natural law ( jus naturale) gives the individual absolute freedom to do whatever his power allows
him to do: ‘Every man has a right to everything’. Natural law depends on the strengths o f each
individual. Any idea of justice will only appear with formal laws: there is no justice to the state of
nature (contrary to what Locke argues, for example).
3. The result is a situation of chaos with rife potential for civil war. Permanent insecurity and dan-
ger characterise this natural state, which Hobbes sees as a state approximating that of war. No
one is ever really at peace in this situation, and in order to defend oneself, it is necessary to
attack others. The state of nature is therefore characterised by struggles ‘of each against each’.
4. In these circumstances, the overwhelming need of human beings is security.
5. The means to achieve security can only come in the form of law – not ‘natural law’, which is a
source of freedom rather than constraint, but social law. Consequently, it is inevitable that each
individual decides to enter into a contract with each of the others, in order to abdicate part of
their power in favour of a common authority with absolute power, the State, or Leviathan,
described as a ‘mortal god’. Only a strong authority is capable of guaranteeing everyone the
preservation of their lives and property. Put another way, government, according to Hobbes,
must flow from a covenant of each person to each other – not to the sovereign – in which
all cede to the sovereign their right to govern themselves and their freedom so that the will
of the sovereign brings the wills of all individuals to one single will. It is important to note
that the contract is at this stage ‘horizontal’, not ‘vertical’ (the contract of association).
‘The only way to erect such a common power, as may be able to defend them from the invasion
of foreigners, and the injuri es of one another, and thereby to secure them in such sort as that by
their own industry and by the fruits of the Earth they may nourish themselves and live content-
edly, is to confer all their power and strength upon one man, or upon one assembly of men, that
may reduce all their wills, by plurality of voices, unto one will’ (chap. XVII).
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Hobbes explains that the state can take three forms, depending on how power is exercised: by a single
man in a monarchy, by the assembly of citizens in a democracy, or by a small circle in an aristocracy
(chap. XIX). He is a strong advocate of absolute monarchy, considering this type of regime to be the
most suitable for ensuring peace and security for the people (II, 19). The two characteristics of the
government contract according to Hobbes are: the fact that submission must be total; and the fact
that the ruler himself is not bound by the contract (i.e. his power is absolute). Total submission on
the one hand and absolute power on the other are the sine qua non conditions of a civil state –
that is, a state of peace. Indeed, the mere possibility of recourse against the sovereign would lead to
a return to the struggle of each against each.
2.3. Locke
Locke shares with Hobbes his contractual doctrine of the state, and also his determination to found
this doctrine in opposition to a previously dominant theory of the divine right of kings revealed by
scripture. In the First treatise he spends most of his time demolishing the Patriarcha of Sir Robert
Filmer, which was one of the most influential texts defending such a doctrine of scriptural revelation.
Nevertheless, Locke develops the argument in a very different way from Hobbes. Starting from very
different premises about the state of nature, he reaches very different political principles (Two treatises
of government, Locke, 1689b). This reminds us that the content of these philosophers’ claims about the
state of nature plays a crucial role in justifying their normative conclusions.
For Locke, the state of nature is a state of harmony and reasonable freedom. He describes it in
Chapter 2 of the Second Treatise as:
a state of perfect freedom to order their actions, and dispose of their possessions and persons as
they think fit, within the bounds of the law of Nature, without asking leave or depending upon
the will of any other man. A state also of equality, wherein all the power and jurisdiction is recip-
rocal, no one having more than another, there being nothing more evident than that creatures of
the same species and rank, promiscuously born to all the same advantages of Nature, and the use
of the same faculties, should also be equal one amongst another, without subordination or sub-
jection, unless the lord and master of them all should, by any manifest declaration of his will, set
one above anoth er, and confer on him, by an evident and clear appointment, an undoubted right
to dominion and sovereignty.
Individuals in the state of nature enjoy two powers and a fundamental right: the power to ensure their
own conservation; the power to punish anyone who threatens their life; and the fundamental right of
ownership limited to what is necessary for its conservation. Contrary to Hobbes, Locke recognises nat-
ural rights: he argue s that people have rights, such as the right to life, liberty and property, that have a
foundation independent of the laws of any particular society. This is not, of course, an empirical dis-
agreement with Hobbes in the ordinary sense of the term, but rather a difference of values.
Nevertheless, Locke’s view of the state of nature as harmonious (an empirical claim) helps to make
the claim that people in it enjoy certain rights less contrived than it would be in a state of total
fear such as that described by Hobbes.
The right to property contains two interesting elements. First there is a version of a labour theory of
value:
Whatsoever, then, he removes out of the state that Nature hath provided and left it in, he hath
mixed his labour with it, and joined to it something that is his own, and thereby makes it his
property (Second Treatise, Chapter V, paragraph 27).
The second is a requirement, which acts as a qualification to the labour theory of value, that the act
of appropriation should not harm the opportunities for appropriation by others:
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For this ‘labour’ being the unquestionable property of the labourer, no man but he can have a
right to what that is once joined to, at least where there is enough, and as good left in common
for others (Second Treatise, Chapter V, paragraph 26).
In terms of the five matters we outline above, Locke’s view of human nature is as follows:
1. Locke’s view of the fundamental motivation of humans is different from that of Hobbes in that
the passion for power is less dominant. People are more bourgeois and less martial than for
Hobbes (Macpherson, 1962) – violence is more the product of the wish to steal others’ resources
than to exercise domination over them (nevertheless, for a reminder of Locke’s awareness of the
recent history of political and especially religious violence, see Tully (1980, 1993)).
2. Locke also differs from Hobbes in that he considers natural law to constrain human behaviour
in the state of nature. Although this represents a difference of values and not of simple fact, it is
a claim that makes more sense in a relatively peaceful state of nature than it would in a
Hobbesian struggle of all against all.
3. Although the state of nature is indeed more harmonious than it is for Hobbes, it is still regularly
threatened by insecurity. It also contains enough material abundance that the right to appropri-
ate nature by mixing it with one’s labour does not regularly prevent their being ‘enough and as
good left in common for others’.
4. Security is necessary to achieve peace and prosperity, which are fundamental goods for Locke
(he places more value than Hobbes on prosperity).
5. Individuals therefore enter into civil status by a contract of association (mutual consent) and a
contract of conditional submission. Unlike for Hobbes this submission is only conditional.
Locke believes that no legitimate (i.e. freely consented) government can be an absolute govern-
ment. No one would be foolish enough to consent to give up all their rights, because then the
state of society would be worse than the state of nature (the same idea will be found in
Rousseau). Locke’s idea is that, in civil states, the rule is that of the majority and not of an all-
powerful authority. Furthermore, the government contract is dissolved as soon as the majority
considers the government to be inadequate, i.e. unable to provide security.
2.4. Rousseau
In The social contract (published in 1762), Rousseau’s stated objective is also to determine the source
and principles of legitimate political authority. In the first lines of Book 1, he states his aim very
clearly: ‘My purpose is to consider if, in political society, there can be any legitimate and sure principle
of government, taking men as they are and laws as they might be’ (Rousseau, 1762).
The precise character of the state of nature is not much discussed in that book, but it had been
treated extensively in his earlier Discourse on the origin and bas is of inequality among men, published
in 1755, five years before On the social contract. The entire first part of this earlier text is devoted to the
state of nature, which is described as ‘simple, unchanging and solitary’ (Rousseau, 1755). Individuals
do not think, do not communicate beyond the most rudimentary means (gestures) and live essentially
in the present. The only feelings in this state of nature are a concern for self-preservation (‘amour de
soi’), as well as a minimal sense of pity for others. The cohabitation of the two guaranteeing a certain
balance, none wanting to inflict unnecessary harm on others.
For Rousseau, this state of nature disappeared long before his own time. However, Rousseau looks
for examples of indigenous peoples to discover what could give us the best idea of this state. The closest
example of this state of nature is according to him that of the ‘Caribbean savages’, about whom his
information was of course somewhat limited.
Rousseau believed that, in the state of nature, individuals live in the present, and find all of the
resources to meet their basic needs. Individua ls are essentially solitary, the family itself being for
Rousseau only a notion invented later.
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The state of nature is a state where inequalities are minimal. It is society and the associated formal
institutions that create and exacerbate inequalities, first by creating new inequalities, the first and most
important of all being through the invention of property, but also by exacerbating natural inequalities
of talent, for example through formal schooling. Moreover, in the state of nature, individuals have very
little power over each other; indeed, even inequalities of strength are not enough to subjugate each
other, because in this state of nature, anyone can always leave.
The second part of the Discourse is devoted to telling the story of this exponential progression of
inequalities, which begins, as noted above, with the invention of property. Rousseau traces its origins
and later development back to the inventions of agriculture and then metallurgy. The appearance of
property, the increasing inter-dependencies which resulted from the division of labour, and the feed-
ing of passio ns born of other men’s trade, made conflicts between men more and more permanent and
violent. Then came the creation of magistrates, exercising politic al superiority over others, until the
appearance of the ultimate form of inequality: despotism and absolute submission.
At this point Rousseau attacks both Hobbes and Locke head-on. He blames both for confusing
various states of civil society with the state of nature. Hobbes takes as a state of nature the struggles
of all against all to justify absolutism. In addition, Locke integrates the notion of property into the
state of nature, which leads him to defend the social contract as the means of protecting this property.
For Rousseau, on the contrary, it is this very notion of property that marks the exit from the state of
nature.
In terms of the five matters we outline above, Rousseau’s view of human nature is as follows.
Rousseau gives his first definition of human nature in Chapter II of Book 1:
This common liberty is a consequence of man’s nature. Man’s first law is to watch over his own
preservation; and as soon as he reaches the age of reason, he becomes the only judge of the best
means to preserve himself; he becomes his own master.
The first and main motivation of individuals is self-preservation; and as each can best judge what is
best for them, liberty is an absolutely essential feature. This feature is common with Hobbes and
Locke. Later, Rousseau diverges from these authors, as he describes the state of nature as a state
where individuals live in isolation, ‘entirely complete and solitary’ (Chapter VII, Book 2).
Rousseau also had ideas about the extent of human preferences for the present over the future. In
the Discourse he wrote that the soul of
the savage man … which nothing disturbs, dwells only in the sensation of its present existence,
without any idea of the future, however close that might be, and his projects, as limited as his
horizons, hardly extend to the end of the day. Such is, even today, the extent of the foresight
of a Caribbean Indian: he sells his cotton bed in the morning, and in the evening comes weeping
to buy it back, having failed to foresee that he would need it for the next night.
Quite where Rousseau obtained this implausible information he did not say.
Rousseau is evasive about the reasons underlying the transition from the state of nature, where indi-
viduals lived in isolation, to living together. His objective is not to describe how human beings ended
up living in large groups, but what the legitimate ways are of funding and organising such societies.
The answer to this question is given in the first sentence of Chapter 1: ‘Man is born free; and he is
everywhere in chains’. This is the main topic of the Discourse on the origin and basis of inequality
among men, describing the modern condition as dominated by inequality, dependency, war and mis-
ery. Almost everywhere, humans have lost their autonomy and freedom.
For Rousseau, entering into a harmonious social commun ity has the potential ‘to change human
nature, to transform each individual, who by himself is entirely complete and solitary, into a part
of a much greater whole’ (Chapter 7 of Book II). This answer is essentially the same as that given
by Hobbes and Locke.
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Given that autonomy and liberty are essential qualities of an individual, the only legitimate foun-
dation of society is the unanimous consent of all: ‘the Social Contract’. The whole population taken
together forms the sovereign; it represents the general will and possesses the legislative power. The gov-
ernment, distinct from the sovereign, deals with the application of law and other particular matters.
Rousseau forms the theory of the ideal constitution. Yet he remains always wary that this is an unstable
state. Because of the first law of human nature, self-interest will be present, and creates at least two
kinds of tensions: the first b etween each individual and the sovereign (the general will), and the second
between the sovereign and the government, the latter always being tempted to act in its own interest.
3. Empirical evidence
3.1. What motivates human beings
Under what conditions is human social behaviour motivated by selfishness, cooperation, altruism and
spite? The answers are central for evaluating the validity of descriptions of individuals in the state of
nature, and reasons underlying demands for social contracts. Whether from an evolutionary economic
perspective selfishness and cooperation (both of which entail fitness benefits for actors) are easier to
explain than altruism and spite (which entail fitness costs for actors) has been the topic of much
debate since roughly the middle of the twentieth century (see Alger & Weibull, 2019 , for a review
of theoretical models of preference formation in social interactions).
Modern research in behavioural economics has greatly enhanced our ability to adjudicate rival
causal claims about the relative importance of selfishness and altruism, in particular in individual
human motivation. Mainstream economics assumed that individuals were selfish unless given incen-
tives to behave otherwise. The long-standing claims by other disciplines including anthropology, biol-
ogy and psychology for the existence of what are now called ‘social preferences’ (not only positive ones
such as reciprocity but also negative ones such as envy) were dismissed by traditional economists as
just the social manifestation of rational self-interest.
For example, it was commonly ar gued that people might behave apparently altruistically just
because of the selfish benefits to be gained from others’ response to this behaviour. The result was
that different branches of the evolutionary social sciences made different assumptions abou t human
motivation as a matter of methodological preference or other considerations (such as mathematical
tractability), and different flavours of political philosophy made different assumptions about human
motivation out of equally unchallenged prior conviction. All sides appealed abundantly to anecdotes,
and few effo rts were made to look to systematic empirical en quiry to settle their differences.
This changed, in part, with laboratory experiments in the field of what has now come to be called
behavioural economics. What these experiments made possible was to observe how individuals
behaved when interacting with anonymous others (e.g. owing to double-blinded study designs),
and whom therefore they would never knowingly encounter again – thereby ruling out strategic
motivations for displaying apparently altruistic or cooperative behaviour. Yet instead of revealing
that individuals in such contexts behave purely self-interestedly, the experimental literature has
shown that under a wide range of circumstances they:
• make altruistic donations to individuals they will never meet (Forsythe et al., 1994);
• respond to the behaviour of others with strong reciprocity – being generous to those who have
been generous to them, and mean to those who have been mean to them (Fehr et al., 1993, 1997;
Fehr & Schmidt, 1999);
• are willing to contribute to public goods, but quickly reduce their willingness if they believe it is
being exploited by others who are free riding (Fehr & Gächter, 2000);
• are willing to punish those whom they believe to be cheating or unjust to others, even at a cost to
themselves and even if they themselves have not been directly harmed by the cheating or unjust
act (Fischbacher, 2001; Fehr & Fischbacher, 2004).
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It is important to emphasise that there is a wide variety of findings, and this literature has not replaced
the uniform view that human motivation is selfish by a similarly uniform view that it is characterised by
any particular configuration of social preferences. Nevertheless, the validity of the rational egoism view
is now seriously in doubt. Legitimate questions can be and have been posed about the ecological validity
of such anonymous experiments (Pisor et al., 2020), the interpretation of findings from ecologically
valid studies (such as natural field experiments; see Winking & Mizer, 2013 for an example) and
their relevance to small-scale societies. Indeed, the vast majority of economic experiments have been
conducted with subjects from so-called WEIRD populations (Western, Educated, Industrialised, Rich
and Democratic – see Henrich, 2020). Precisely because of such concerns, major efforts have been
made in recent years to conduct economic experiments in a range of small-scale and other non-
WEIRD societies, and results indicate substantial heterogeneity (Engel, 2011).
Some of the behaviours highlighted above (e.g. willingness to punish others at a cost to oneself)
have been found in populations from many different societies and classes within societies (Henrich
et al., 2001, 2006). There is substantial variation among individuals in any society.
All known study populations contain some purely self interested individuals as well as others with a
variety of types and degrees of social preferences including altruism and spite. Yet nobody can any
longer maintain that the hypothesis of rational self-interest is descriptively accurate for humans,
although there remains much room for argument about how useful this hypothesis can be as a work-
ing approximation in certain political and economic contexts.
It is a somewhat subtle matter to judge just how much of a revelation these findings would have
seemed to the philosophers whose views we have outlined. Locke and Rousseau came closest to think-
ing that man in the state of nature corresponds to the picture of Homo economicus that modern
evolutionary social science has shown to be so incomplete; to the extent that more other-regarding
motivations were possible these would have been considered to be the result of social pressures.
Ancient thinkers such as Aristotle or Confucius would doubtless have been much less surprised,
since they explicitly accepted that humans could be motivated by other than selfish objectives.
Hobbes, in contrast, already admitted other forms of motivation, but chiefly the more destructive
kinds such as spite. He would probably have been surprised to discover that humans are regularly
capable of behaving altruistically to strangers they never expect to meet again.
With respect to time-preference, there is some evidence, drawn from studies of material preferences
using forced-choice paradigms, that individuals in forager–horticultural societies are more
present-oriented and discount future rewards (Kirby et al., 2002); this may deter material wealth
accrual. However, it is hard to know whether this reflects intrinsic time-preference or different sets
of beliefs about the probability of receiving future rewards. And there is certainly no evidence at all
suggesting that inhabitants of small-scale societies are unable, as Rousseau thought, to foresee their
material needs 24 hours in advance.
3.2. What constraints we face from our natural and social environments
The social contract theorists we have considered believed that the natural state of individuals was any-
thing but social. Hobbes famously wrote that the state of man was ‘solitary, poor, nasty, brutish and
short’. Rousseau also considered the state of nature to be solitary.
This picture is radically at odds with what we now know to be the shared characteristics of all
known human societies. Across small-scale societies there is a modal pattern of social organisation
characterised by a three-generational system of resource flows (including co-resident offspring, par-
ents and grandparents), a sexual and age-graded division of labour within long-term adult pair
bonds (Alger et al., 2020) and hig h levels of cooperation between kin and non-kin (Kaplan et al.,
2000). Human hunter–gatherers were probably highly inter-dependent long before the invention of
agriculture, contrary to Rousseau’s claim that agriculture and its associated divisions of labour
paved the way for high inter-dependencies.
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Despite the popular idea that hunter–gatherers are organised in a system of small groups of cor-
esiding kin, their social structure is actually quite fluid and comprises networks of interaction between
spatially and genetically distant individuals that extend far beyond a local residential group (Bird et al.,
2019; Hill et al., 2011; Migliano et al., 2017; Wiessner, 1982).
In the archaeological record, ‘base camps’–which reflect key organisational components of forager
sociality facilitating cooperation – are evident at least 400,000 years ago (Kuhn & Stiner, 2019).
Similarly, genetic evidence of interbreeding between early modern and archaic hominins reveals the
formation of expansive kinship ties, and possibly cooperation, at least 100,000 years ago (Kuhlwilm
et al., 2016).
Modern psychological and behavioural evidence supports this impression. Experimental studies
suggest that we have an evolved cognitive specialisation for reasoning about social exchange and for
social learning (e.g. Cosmides & Tooby, 1992; Derex & Boyd, 2018; Derex et al., 2019; Sugiyama
et al., 2002), which is not expected for a ‘solitary’ organism. Likewise, analysis of systematic behavioral
observation data from a large sample of Tsimane forager–horticulturalists of Bolivia (n = 50,349
instantaneous scans of 608 individuals) shows that across all sex and age categories, only 2.4 daylight
hours per day are spent ‘alone’, defined here as either not within 3 metres of at least one other indi-
vidual, or not involved in a conversation (unpublished data).
Not all of this intera ction has a positiv e connotation, of course – far from it. Despite Rousseau’sinsist-
ence that humans outside of ‘civilised’ society as he knew it wer e: ‘wandering in the for es ts, without war …
equally without any need of his fello w men and without any desire to hurt them’ (Rousseau, 1755 [1984]),
human warfare probably pre-dated agriculture, sedentary residential arrangements and the formation of
larger-scale societies (see Glo w acki et al., 2020 and references therein). Whether w arfare is indeed mor e
prevalent in non-sta te vs. state societies is vigourously deba ted. Interstate warfare has become less com-
mon over time in many world regions (Pinker, 2011), although some regions remain chronically
entrenched in war (Morris, 2014).Thefactthatsomehunter–gather er groups traded and intermarried
withothergroups(Fry,2005) indicates that inter-group relations among non-sta te societies are not neces-
sarily hostile (as is the case for our close chimpanzee relatives), but instead could alternate betw een col-
labora tion and hostility in r esponse to changing incentives. How ev er, Peterson and Wr angham
(1997) emphasise the stra tegic chara cter of much violence even among chimpanzees: the probability
that encounters turn violent is highly influenced by per ceiv ed fitness costs and benefits of aggr ession.
3.3. What kind of society emerges in communities lacking formal institutions
The word ‘poor’ in Hobbes’s description of life in the state of nature does indeed correspond to some
aspects of reality in small-scale societies. Perhaps the most important consideration, though, is not
average levels of wealth but the equality or inequality in the distribution of that wealth. Because, in
general, resources are much more equally distributed in small-scale compared with larger-scale soci-
eties, material poverty in small-scale societies may be experienced very differently from poverty in
societies with significant storable and heritable wealth and wealth inequalities (Jaeggi et al., 2020).
Wealth can be defined in various ways: (1) material, (2) relational and (3) embodied (Borgerhoff
Mulder et al., 2009). The relative paucity of owned, defensible and transmittable material wealth
among many hunter–gatherers (exceptions notwithstanding, e.g. Ames, 2003; Rowley-Conwy, 2001)
entails comparatively minimal wealth inequality. Relative egalitarianism in material resource access
limits the formation of rigid, pronounced gradients in health and longevity along status lines that reli-
ably emerge among humans and other primates (e.g. Kondo et al., 2009; Marmot et al., 1991; Sapolsky,
2005). Minimal wealth inequality diminishes subjective experience of deprivation and subordination
and associated adverse health consequences, including chronic psychosocial stress and depression (see
Snyder-Mackler et al., 2020 for an overview). Foragers who have been able to intensify resource
exploitation and produce storable food surpluses which are then defended and transmitted are excep-
tions that prove the rule: alongside stable material wealth differentials we observe among some foragers
status-graded variation in well-being, including the existence of slavery.
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Status hierarchies do indeed exist across diverse small-scale societies, but rather than resulting sim-
ply from variation in material wealth, they are often linked to relational wealth (i.e. social ties in mar-
riage, food-sharing and other cooperative networks) and embodied wealth (i.e. physical and cognitive
abilities, such as strength and knowledge/skill, underlying variation in food production and reproduct-
ive success).
At the same time, as Hobbes intimated, inhabitants of smal l-scale societies often face undesirable
physical conditions including harsh and unpredictable environments (e.g. extreme temperatures,
omnipresent insects), predation, diverse infectious diseases (a major cause of mortality), and food
and water shorta ges.
Nevertheless, Hobbes’s erroneous characterisation of life in small-scale societies overlooks numer-
ous enjoyable leisure activities within such societies, including storytelling (Schniter et al., 2018; Smith
et al., 2017), music-making, singing and dancing (Mehr et al., 2019), sport (Trumble et al., 2012) and
communal beer-drinking (Hooper et al., 2013), that have long been posited to play central roles in
socialisation, information exchange and/or entertainment, but whose form and function are only
recently being understood empirically. Beer drinking is of course a product of post-agricultural soci-
eties, but consumption of psychoactive plant substances – which may have been used in various col-
lective activities (e.g. ceremonies, recreation, labour) – may have a longer history that predates the
Neolithic (Hagen & Tushingham, 2019).
Notwithstanding the recurring potential for violence in small-scale societies, Hobbes’s use of the
word ‘brutish’ also seems quite inaccurate to describe the subtle mechanisms deployed in many
such societies to manage conflict. Precisely because overt conflict or its threat was frequent, we
would expect strong selective pressure to evolve strategies for managing conflict. This point has
been explored in particular detail in de Waal ( 2017).
Boehm (1999) documents the many ways in which the relatively egalitarian social structure of some
hunter–gatherers both requires and facilitates respect for individual autonomy. Potentially powerful
individuals cannot easily dominate, and if they try they face countervailing pressure from coalitions
of others (see Gavrilets, 2012, for a theoretical application). Violence is often shunned in daily life
(e.g. Tacey & Riboli, 2014); its sanctioned use is generally reserved for extreme cases (e.g. punishing
murderers). Excessive use of violence for punishing norm violators often entails moral outrage
(Mathew, 2017) and reputational and other costs to overly aggressive norm enforcers. Wrangham
(2019) provides an overview of the strategic use of aggression to discipline individuals who are exces-
sively prone to exercise what he calls ‘reactive aggression’ (i.e. a response to a threat or frustrating
event, with the goal being only to remove the provoking stimulus), and suggests that this human ten-
dency played a major role in our physical and psychological evolution.
Among Aka hunter–gatherers of the Central African Republic, individuals ‘cite physical or verbal
fighting as one of the worst things one individual can do to another, along with not sharing, stealing
food or husbands/wives, and sorcery’ (Hess et al., 2010: 338–339).
In many small-scale societies a common response to conflict is for one or multiple involved parties
to disperse to another residential group (for short or longer durations, as Rousseau intimated).
Relocation costs are relatively low in the absence of formal property rights. When norms are violated
within the group, punishment commonly takes the form of criticism, shaming, ridicule, ostracism,
mocking or even joking rather than violence (Wiessner, 2005).
Third-party mediation is another common strategy for peacefully resolving disputes, and conflict
resolution is a common function of leaders in small-scale societies (see Garfield et al., 2020 and refer-
ences therein). Other tactics for minimising aggression include arranging marriages for young girls
(e.g. Shostak, 1981), which can serve to reduce male competition and unite in-laws. Maintaining
group cohesion and reducing tensions can also be accomplished through trance healing dances and
‘fireside chats’ (Wiessner, 2014
).
Even families involved in lethal conflicts can avoid the temptation of enacting revenge, e.g. by por-
traying the incident as a random and isolated incident (e.g. owing to intoxication), or by regarding an
aggressor as mentally unstable and not deserving of further attention.
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Finally, Hobbes’s characterisation of life in the state of nature as ‘short’ was in important respects
mistaken. It is true that recorded human life expectancy has increased linearly by three months per
year over the past 160 years (Oeppen & Vaupel, 2002), with improvements in sanitation, nutrition
and public health accounting for much of this change. Life expectancy at birth is projected to continue
increasing in industrialised countries worldwide through 2030, largely owing to enhanced longevity at
older ages (Kontis et al., 2017). By 2030 female life expectancy may exceed 90 years.
Such high survival rates have probably never occurred before in human history. Nevertheless,
despite their lower life expectancies, hunter–gatherer and horticultural populations with limited access
to medical care and sanitation are likely to reach middle age and older adulthood if they survive
early childhood (Gurven & Kaplan, 2007). High infant and child mortality yields a life expectancy
at birth of 21–37 years for hunter–gatherer populations, but conditional on survival to age 15
years, the modal age of death for hunter–gatherers, horticulturalists and even eighteenth-century
Europeans ranges from 68 to 78 years. Human longevity is therefore not simply an artefact of
improved living conditions.
Moreover, many chronic causes of morbidity and prevalent causes of mortality in industrialised
populations (e.g. cardiovascular disease, diabetes, obesity, hypertension, also known as ‘diseases of
civilisation’) are rare or absent in small-scale societies (e.g. Gurven et al., 2012; Kaplan et al., 2017).
This apparent paucity of non-communicable disease is not a result of short lifespan. Rather, various
features of lifestyle such as lean and high-fibre diets free of processed foods, high physical activity
levels, minimal smoking and other behaviours are protective factors common to many small-scale
societies.
3.4. What constitutes a fulfilling life?
It might seem as though empirical evidence would hardly be relevant to the question of the good life
for humans, which is essentially a matter of value judgements. However, this ignores the fact that
evidence from small-scale societies has yielded some valuable insights into aspects of daily life that
are reliably associated with mental health, or with various forms of psychological distress including
depression. A philosophical theory of the good life for humans is not just a set of value judgements,
but also a (loosely) empirical set of hypotheses about the kinds of activities that lead to humans’ judg-
ing their lives to be worthwhile, and that lead to human flourishing. Of course, some philosophers
have accorded greater weight than others to the judgements of individuals, who are not necessarily
considered the best judges of what is good for them. Some (like Nietzsche) have even attacked the
idea that contentment with one’s life is a desirable state, considering that various forms of striving
are far more noble ideals even if these bring stress and disappointment in their wake.
Nevertheless, it is worth noting that evidence has accumulated in recent years in favour of the view
that, although there is much between- and within-societal variation in what individuals consider to be
worthwhile forms of living, the majority of individuals derive important benefits from intrinsically
social aspects of their lives – their networks of family, friends, colleagues and neighbours. Even if
some material circumstances are capable of causing great unhappiness – physical illness is a frequent
cause of depression, for example – above a certain level of material comfort the contribution of mater-
ial prosperity to human fulfilment is relatively unimportant.
Psychologists have recognised that human interdependence shapes the self-concept (Markus &
Kitayama, 1991) such that social identity is an essential component of self-concept (‘identify fusion’).
Ingroup fusion indeed predicts costly self-sacrifice in economic experiments among subsistence and
market-integrated populations (Purzycki & Lang, 2019).
Given the importance in terms of biological fitness of inter-individual transfers of resources and
assistance in every phase of the human life course (Lee, 2014), it is likely that human psychological
well-being responds to the nature and quantity of those transfers (Stieglitz et al., 2014). In particular,
deviations of resource transfers from expectations can affect psychological well-being. Resource flows
can be disrupted for various reasons; one principal source of disruptions is the inability to provide
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support for others owing to disability, illness, or some other permanent or temporary shock. Given
that downward resource transfers from older to younger individuals are expected in small-scale soci-
eties and that illness and disability become increasingly prevalent with age, the inability to provide and
share expected resources can be a principal driver of reduced psychological well-being among aging
adults. Limited evidence from small-scale societies (Stieglitz et al., 2014, 2015) suggests that risk of
depression increases with age, as health, functional ability and productivity decline, and is not char-
acterised by a ‘mid-life crisis’ as in modern societies (Blanchflower & Oswald, 2008).
3.5. Collective solutions
Space constraints prevent us in this paper from reviewing the massive literature on political arrange-
ments in small-scale societies, as well as from distinguishing as much as we would have liked between
more or less segmented forager societies (see Garfield et al., 2019, for a substantial review of one key
dimension of political arrangements, namely political leadership). However, we can make some obser-
vations about the extent to which particular informal social institutions have proven robust in the face
of individual incentives to disrupt them.
The work of Boehm (1999) cited above suggested that the relatively e galitarian distribution of
both material resources and power in ce rtain small-sc ale societies was the product not of an absence
of competitive instincts among their inhabitants but rather an equilibrium in which those competi-
tive instincts were kept in check by the cou nterv ail ing power of others. Furthermore, a talent for
mobilising such countervailing power was suggested by Boehm to be one of the major adaptive
innovations of the human social order under certain conditions. To the extent that that countervail-
ing power was successful, its mobilisation coul d be considered a significant public goo d. At least
in egalitarian hunter–gatherers, in contrast to the views of Machiavelli a nd Hobbes, influence is
exerci sed largely through prestige rather than dominance, a distinction emphas ised by Henrich
and Gil-White (20 01).
Small-scale societies have also shown considerable ingenuity in mobilising their members to provide
other kinds of public goods, including participation in hunting and defence operations (Boyd, 2017).
Such participation is clearly strategic and responsive to the fitness benefits of collective action. In par-
ticular, as emphasised by Glowacki et al. (2020), ‘warfare is a strategy by which coalitions of males
cooperate to acquire and defend resources necessary for reproduction. This strategy is not the result
of a single “instinct” for war, but is instead an emergent property resulting from evolved psychological
mechanisms (such as xenophobia and parochial altruism). These mechanisms are sensitive to ecological
and social conditions, such that the prevalence and patterns of warfare vary according to subsistence
strategies, military technology, cultural institutions, and political and economic relations’.
It is notable that the small-scale societies that have implemented collective action in this manner
have all done so in spite of the absence of formal legal institutions, which suggests that the social con-
tract theorists considerably underestimated the ability of human societies to find informal solutions to
the problems generated by the state of nature.
Among the chief mechanisms for achieving collective action has been the establishment and enforce-
ment of norms (Boyd, 2017) for policing perceived anti-social behaviour. In small-scale and other soci-
eties, theft is perceived as immoral, worthy of firm punishment and damaging to one’s reputation
(Barrett et al., 2016). This would of course have been less surprising to earlier thinkers – C onfucius,
for example, laid particular emphasis on righteousness, namely on maintaining integrity in the face
of temptation. Relatedly, language in small-scale societies reveals a broadly similar set of normative con-
cerns. A lexical study of ‘human attribute concepts’ (i.e. traits ascribable to humans) in 12 isolated lan-
guages spanning most habitable world regions outside of Europe found that jealousy and crookedness
are relatively ubiquitous human traits (Saucier et al., 2014). Similarly, honesty and dishonesty are
among the most salient cross-cultural indicators of good and bad people, respectively, based on free-list
responses capturing local attitudes (Purzycki et al., 2018). Marital infidelity is regarded harshly cross-
culturally (Scelza et al., 2020), and is the most commonly cited reason for divorce (Betzig, 1989).
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Given the importance of inter-dependence for survival throughout human history, it has been hypothe-
sised that the emotion of shame evolved to avoid or minimise social costs incurred from committing
immoral acts (Sznycer et al., 2018).
Along with such norms there is widespread acceptance of the idea that virtuous people should be
sought out as social partners, and that anti-social individuals should be shunned. ‘Lab in the field’
economic experiments among Hadza hunter–gatherers of Tanzania and Tsimane forager–horticultur-
alists of Bolivia indicate that, despite substantial residential mobility, cooperators are preferentially
connected to other cooperators in social networks (Smith et al., 2018; Stieglitz et al., 2017). In Bwa
Mawego, Dominica, men with better altruistic reputations form more same-sex reciprocal labour
partnerships than men with poorer reputations (Macfarlan et al., 2012). Finally, the Hadza appear
to agree on which traits constitute moral character (i.e. being a hard worker, generosity and honesty)
but disagree on which specific camp mates actually exhibit these traits (Smith & Apicella, 2019), sug-
gesting plasticity in individual dispositions depending on context.
In addition to providing public goods and policing anti-social behaviour, individuals in small-scale
societies also engage in other kinds of collective activity of a kind that can be described as rituals, the
difference being that in rituals the activity is itself constitutive of the collective benefit being provided,
rather than merely being instrumental in its provision as is the case for public goods. Although the
social contract theorists did not attach much if any importance to ritual, thinkers as diverse as
Confucius, Ibn Khaldun (1377) and Durkheim (1915) have argued that rituals promote group cohe-
sion in various ways, including ensuring commitment to collective goals, acquiescence to group tradi-
tions (e.g. moral codes, social obligations, institutions) and deference to authority figures. More recent
empirical research confirms this. In the Tyvan Republic of southern Siberia, ethnic Tyvans who regu-
larly engage in cairn rites (e.g. making offerings to local spirits by burning incense and leaving money,
food or tobacco) are perceived as more trustworthy than ethnic Tyvans, Christian Tyvans and
Christian Russians who do not perform such rites, suggesting that ritual increases bonds between
practitioners (Purzycki & Arakchaa, 2013).
In Mauritius, participation in painful rituals (e.g. dragging heavy objects attached by hooks to the
skin for hours) is associated with greater anonymous charitable donations and more inclusive social
group identification (Xygalatas et al., 2013). In southern India, those who partake in collective ritual
(e.g. monthly temp le worship) are more likely to report between them supportive relationships (e.g.
receiving advice or loans) compared with those who refrain from ritual; importantly, ritual partici-
pants are also able to maintain supportive relationships with non-participants (Power, 2018). Ritual
participants are also perceived as more devout, generous, better advisors and having good character
compared with non-participants (Power, 2017a), and are more likely to act in ways that benefit others
(Power, 2017b). Together, these recent empirical case studies tend to support Confucius’ proposal that
ritual enhances social cohesion, in part by curbing anti-social behaviour and promoting cooperation.
Overall, we can consider that the collective solutions to the challenges that humans encounter fall into
two broad categories. The first category consists of those in which the societies informally mobilise the
efforts of their members to provide various public goods, including in the form of coordinated defence
against or attack of external competitors, or internal dispute management. The second consists of various
collective activities whose nature is performative: the action is itself partly constitutive of the benefit and
is not merely instrumentally useful. Of course, some kinds of activity (including the collective exercise of
violence) may come to acquire a performative character through its repetition over time.
4. Some general questions about the social contract approach
4.1. Did social contract theorists believe the state of nature had ever really existed?
There is a good deal of variation between theorists considered here (and some creative ambiguity) with
respect to whether they believed the state of nature to be a real state that had ever existed, or merely
a rhetorical device to contrast the actual human condition with what we might have been like without
formal institutions. Locke took some trouble (at the end of Chapter 2 of the Second treatise,forexample)
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to defend the view that it had once really existed. Likewise, Hobbes writes in Chapter 13 of Leviathan
that ‘during the time men live without a common Power to keep them all in awe, they are in that con-
dition which is called Warre; and such a warre, as is of every man, against every man’; he uses the present
tense, not the conditional. In the following section he is then very explicit:
It may peradventure be thought, there was never such a time, nor condition of warre as this; and
I believe it was never generally so, over all the world: but there are many places, where they live so
now. For the savage people in many places of America, except the government of small Families,
the concord whereof dependeth on naturall lust, have no government at all; and live at this day in
that brutish manner, as I said before.
Nevertheless, in his arguments Hobbes does not draw on any historical description, but rather on his
abstract reflections about the natural equality of men in terms of physical strength and cunning, which
leads to ‘diffidence ’, by which he means a natural fear of each other. In terms of the way in which
modern game-theorists use equilibrium analysis, we can think of Locke as considering the state of
nature to be an actual outcome of social arrangements under some real conditions, while Hobbes
mainly considered it an ‘out-of-equilibrium’ state, the credible threat of which was enough to persuade
rational individuals to grant legitimacy to the sovereign.
Rousseau’s view is harder to characterise, since he repeatedly uses ambiguous language. For
instance, in Chapter 6 of Book 1 of The social contract, he writes ‘I assume that men reach a point
where the obstacles to their preservation in a state of nature prove greater than the strength each
man has to preserve himself in that state … the only way in which they can preserve the mselves is
by uniting their separate powers’. He is clearly describing a social process, not an exercise in reflection.
On the other hand, he uses the present rather than the past tense and writes ‘I assume’ (‘Je suppose’ in
the original French) in a way that suggests at least some tentativeness about whether such a process
actually occurred. In a passage from the Discourse he even writes ‘Let us begin then by setting facts
aside, as they do not affect the question’.
However, Rousseau’s later descriptions of the origins of the Roman republic (in Chapter 4 of Book 4)
also suggest he believed that his notion of the social contract, even if idealised, captures some real fea-
tures of how at least some societies had historically been constituted. For all three of our social contract
theorists, then, it appears that they hedged their bets about the historical accuracy of the state of nature to
which they appealed in their theories, but were inclined to believe that if the evidence were available it
would have supported their description.
4.2. Was the state of nature conceived as solitary, or merely as lacking in formal institutions?
Once again it is not easy to find an unambiguous answer to this question. Hobbes famously used the
term ‘solitary’, and Rousseau describes human nature as ‘entirely complete and solitary’ (‘un tout par-
fait et solitaire’). Locke does not use the term, and his description of the state of nature does not seem
to indicate solitude at all, since men are constantly fighting over resources. Nevertheless, all three the-
orists seemed to believe that there was a solid foundation to human reason that existed prior to any
process of socialisation, and to which appeal could be made to judge the conditions under which
human beings were to organise their collective lives.
4.3. If the social contract theorists were indeed mistaken about human nature, what difference does
it make to their normative conclusions?
From the studies of small-scale societies that we have reviewed, it is clear that many specific assumptions
that these thinkers made about life without formal institutions were wrong. More importantly, it may be
the whole perspective of the social contract that should be questioned. Indeed, the philosophical basis of
social contract theory is to judge political institutions as legitimate only if they pass the (hypothetical)
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test of being unanimously approved by agents under some specific circumstances (the role of the state of
nature being to describe these initial circumstances). In these accounts, unanimous consent has to be
given by human beings acting in an independent, rational and to some degree solipsistic way. This intel-
lectual construction, which puts emphasis on formal institutions and on an individualistic, society-free
perspective, seems at odds with what we have learned from the evolutionary social sciences including
anthropology. First, formal institutions are certainly not the only way to regulate human behaviour:
social norms and many other coordinating behaviours exist without formal institutions. Second, every-
where, individuals are interdependent and embedded in a network of complex social relations which
shape psychology. Acknowledging this invites us to revisit the notion of contract among solipsistic indi-
viduals populating the state of nature, even if it is used as a rhetorical device.
5. Conclusions
Taking a broad overview of the accumulated evidence from small-scale societies about the questions
that preoccupied the political philosophers whose views we have examined, it is hard not to be struck
by the extent to which they underestimated human behavioural complexity in societies that lack formal
institutions. Philosophers were not the only thinkers to have such biases: the scientific community as a
whole, persuaded of the virtues of codified knowledge and practice in modern social organisation, has
often been surprised over many decades by what communities of social organisms (both humans and
non-humans) can achieve without formal institutions.
It seems therefore that the deployment of the social contract as a device for philosophical reflection,
despite its major value in clarifying what can and should be expected of political institutions, has come
at a cost – namely that of underestimating and perhaps undervaluing the resilience and subtlety of
human behaviour in societies that do not have the formal institutions on which we have come
unthinkingly to rely.
The notion of a state of nature is largely absent from the works of contemporary thinkers of the
social contract, perhaps because of the inherent weakness or the poor empirical foundations of this
concept. For example, John Rawls (1971) keeps the notion of a form of consent/social contract as
the foundation of the legitimacy of political institutions, but the state of nature has been replaced
by the much more abstract notion of an ‘original position’. He writes in the first chapter of A theory
of justice that he wants to propose ‘a theory of justice that generalises and carries to a higher level of
abstraction the traditional conception of the social contract. The compact of society is replaced by an
initial situation that incorporates certain procedural constraints on arguments designed to lead to an
original agreement on principles of justice’. The state of nature has also disappeared from the works of
contemporary thinkers who have sought to revisit the concept of social contract as an explicit unani-
mous agreement among rational individuals. For example, Brian Skyrms (1996) argues for a weaker
notion of agreement, as implicitly emer ging from the dynamic interactions of the members of society.
Here too the notion o f ‘state of nature’ has disappeared (even if in Skyrms’s arguments, the initial con-
ditions may sometimes play an important role, the interpretation is very different).
Although Charles Darwin did not claim to be an expert on small-scale societies, and did not found
an explicit political theory on his empirical convictions about the nature of life in such societies, there
is abundant evidence that he was profoundly aware of the intensely social nature of life prior to the
agricultural and industrial revolutions, and thought this had been so for long enough to shape
human behaviour through natural selection. In one remarkable passage in The descent of man he spec-
ulates as follows:
When two tribes of primeval man, living in the same country, came into competition, if (other
circumstances being equal) the one tribe included a great number of courageous, sympathetic and
faithful members, who were always ready to warn each other of danger, to aid and defend each
other, this tribe would succeed better and conquer the other. Selfish and contentious people will
not cohere and without coherence nothing can be effected. A tribe rich in the above qualities
18 Paul Seabright et al.
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would spread and be victorious over other tribes … thus the social and moral qualitie s would
tend slowly to advance and be diffused throughout the world. (Darwin, 1871, part I, pp. 162–163)
When we reflect on the profound sentence that concludes The descent of man (‘Man still bears in his bodily
frame the indelible stamp of his lowly origin’ (Darwin, 1871, part II, p. 405), we should be in no doubt that
Darwin intended the ‘indelible stamp’ to apply also to human behaviour. However, anyone tempted to
read it as a gloomy statement about our animal nature and the way it pollutes our social behaviour,
might fruitfully compare it with the closing paragraph of the The origin of species, where he writes:
There is grandeur in this view of life, with its several powers, having been originally breathed into
a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law
of gravity, from so simple a beginning endless forms most beautiful and most wonderful have
been, and are being, evolved. (Darwin, 1859, pp. 459–460).
Modern evolutionary social science has affirmed most emphatically the existence of ‘endless forms
most beautiful’ of non-human and human behaviour in small-scale societies, and we believe political
philosophy can only be enriched by taking these explicitly into account.
Acknowledgements. This project is the result of an invitation by Sergey Gavrilets, Pete Richerson and Frans de Waal to
contribute to a special issue to mark the 150th anniversary of the publication of Charles Darwin’s The descent of man.
We are grateful to the editors for this invitation, to Sergey Gavrilets and two anonymous referees, and to Ingela Alger,
Jean-Baptiste André, Nicolas Baumard, John Broome, Zach Garfield, Mark Greenberg, Alissa MacMillan, Catherine
Mohlo and Manvir Singh for comments on an earlier draft.
Contributions. All authors contributed equally to the paper.
Financial support. All three authors acknowledge IAST funding from the French National Research Agency under the
Investments for the Future (Investissements d’Avenir) program, grant ANR-17-EURE-0010.
Conflicts of interest. All authors declare no conflicts of interest.
Research transparency and reproducibility. No data are reported in this paper.
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Cite this article: Seabright P, Stieglitz J, Van der Straeten K (2021). Evaluating social contract theory in the light of evolu-
tionary social science. Evolutionary Human Sciences 3, e20, 1–22. https://doi.org/10.1017/ehs.2021.4
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https://doi.org/10.1017/ehs.2021.4 Published online by Cambridge University Press