Where Does Justice Come From?

Justice is a primitive emotion based on predictability as well as fairness.

Posted Jun 12, 2019

A sense of fairness may be ingrained in all primates. It is an essential ingredient in functional societies because it makes social relationships predictable. Predictability matters because animals must decide whether other individuals are reliable allies or treacherous foes. Well-known individuals are generally more reliable, so there is a strong tendency to favor in-groups and treat out-groups with hostility.

The sense of justice is not the same as wanting equality, although these impulses are intertwined in our evolutionary history.

Avoiding Domination

One of the most basic manifestations of the sense of justice is the idea that one adult must not be subject to the arbitrary whims of another. In hunter-gatherer societies, there was near-complete equality. There was no meaningful status system and one person was generally as good as another. In these societies, the community ensured that no individual would grow in status to the point that they could lord it over others (1).

Men had slightly higher status than women but women asserted their independence in conducting extramarital relationships (2). Adults took precedence over children but child-rearing practices were mostly indulgent rather than authoritarian. Headmen and head women were essentially servant leaders who operated like social workers, and whose primary mission was to resolve disputes between members of the community.

Successful hunters had higher social status than others and attracted extramarital partners. Their pride was kept in check by customary humility that required them to disparage their own achievements.

Family Justice

Although early societies were highly egalitarian—valuing the freedom and independence of the individual—family relationships were never equal. This is most obvious in relations between children and adults, where adults generally assert their will over the child's. This is the principle, although it may not work out that way in practice, as anyone knows who has ever tried to get a child to go to bed on time. In all families, parents lay down expectations for children's conduct. Whether they follow the rules scrupulously or not, children are well aware of them and can expect parental disapproval if they do not live up to them.

Rules of conduct are generally rooted in practical realities. Young children need more sleep than adults and should, therefore, go to bed earlier to obtain sufficient rest. Parents also need children to settle down if they are to rest themselves, so that they may rise refreshed to face a day of work.

There are many different ways of parsing household rules. They may reflect the level of cognitive development of a child who is emotionally ill-equipped to organize his or her day. They may be interpreted as contributing to a child's moral development. Yet, the simplest interpretation is that family justice contributes to the smooth functioning of a household because each individual knows what is expected of them and of other family members.

Spousal Justice

Within the family, if there is a married couple, the partners generally have fairly clear expectations about how the other will behave. If the family is built around a conventional husband-and-wife team, and if there are children present, the primary expectation is that they will pool all of their resources for the benefit of the children.

In the agricultural past, there was a clear division of labor by gender. Men mostly worked on farms and women concentrated their efforts within the home where they raised children, prepared food, and took care of household work. Under the agricultural system, women could expect their husbands to provide adequate food, shelter and other basic necessities. Men could expect their wives to toil day and night providing for free many of the services that underlie modern service economies.

In contemporary societies, most women participate in the paid labor force so there is no longer the same rigid division of labor by gender. Women no longer expect men to support them financially and men no longer expect their wives to perform all of the household work. The emergence of same-sex marriages illustrates how far marriage has departed from the agricultural system of gender specialization.

The sense of what is fair treatment of a spouse has changed greatly in response to the practical circumstances of the modern economy. Yet, some aspects of marriage have not changed greatly, such as the requirement of sexual exclusivity. But even that aspect of marriage can respond to local conditions. Polygamous marriage is common in many societies around the globe and is the preferred form of marriage in some parts of sub-Saharan Africa, as well as for groups like Mormon fundamentalist extremists.

Polygamy can be a difficult form of marriage due to conflict among co-wives. This theme is emphasized in a documentary on the Red Rock community in Utah (Three Wives, One Husband) in which the protagonists spend much of their time ironing out issues of equality in their plural marriages. The focus is on whether co-wives are treated equally and the documentary ignores glaring status differences between men and women.

Hierarchical Justice

If the sense of what is fair varies with the form of marriage, it is also affected by the political system. In a hierarchical society, members of the elite are treated differently from those of lower social standing. Social inequality increased in agriculture-based societies. These permitted the transmission of wealth across generations, be it as stored grain or herds of animals. Ownership of land was itself a source of inequality. Among Europe's earliest farmers, the elite were those who owned highly fertile loess soil that favored health and fertility and enhanced the attractiveness of male owners to prospective brides (3).

Highly unequal societies are not necessarily conflict-riven. One reason is that there are detailed rules about how people interact with their social superiors or inferiors. Subjects accept that it is their duty to bow before the monarch, for instance, and the monarch can expect inferiors to treat him or her with universal respect.

In status-graded societies, such unequal obligations and privileges are considered fair and just. Their derivation may have a shaky foundation, whether it is the doctrine of the divine right of English monarchs, or the belief that worshiping the Aztec emperor was necessary for a good corn harvest.

Social Predictability as the Bedrock of Justice

Arbitrary or not, ideas of justice revolve around fixed expectations about how other people should behave that facilitate smooth functioning of societies, whether equal or despotic. There is evidence that a sense of justice develops in the brains of all primates, helping them to regulate their social interactions.

In one amusing demonstration of this, monkeys accustomed to getting paid with a grape for the work of pulling a lever were irate when they were given a less desirable piece of cucumber instead (4). Although they eat cucumbers, the outraged monkeys refused to work for lesser "pay" than other monkeys were getting. Justice often means getting what we expect to get.


1 Boehm, C. (2000). Hierarchy in the forest. Cambridge, MA; Harvard University Press.

2 Shostak, M. (1981). Nisa: The life and words of a !Kung woman. Cambridge, MA: Harvard University Press.

3 Bentley, R. A., Bickle, P., Fibiger, L., Nowell, G. M., Dale, C. W., Hedges, R. E. M., et al. (2012). Community differentiation and kinship among Europe'a first farmers. Proceedings of the National Academy of Sciences, 109(24), 9326-9330. doi: 10.1073/pnas.1113710100

4 Brosnan, S.. F., and deWaal, F. B. (2003). Monkeys reject unequal pay. Nature, 425(6955), 297-299.

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