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The Evolved Mathematics of Cooperation

What game theory tells us about our morals.

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By studying the advantages of various behavioral strategies, game theory gives us a peek into what actions are beneficial to genes, and are therefore likely to have evolved. We can extend this framework to moral values as well. By studying the moral strategies that are likely to propagate genes, we can get a good idea of what morals have most likely evolved. Combined with scientific studies to confirm the presence of such moral values, we may begin to develop a deeper understanding of the sorts of moral decision-making processes people endorse.

Oliver Scott Curry and his colleagues have taken this approach to understanding what psychological mechanisms are at play in the moral sphere. Rooted in game theory, and backed by increasing empirical evidence, he’s made the case for at least seven types of moral principles that guide human cooperation (the basis of morality) to greater or lesser degrees around the globe

Preferential treatment of family. The greater the degree of shared genetics, the more likely we should be to help an individual. It is strategic to help our siblings more than our cousins, and our cousins more than strangers. Thus, we would expect morals to evolve which compel us to be altruistic toward our kin. And indeed, around the globe, people feel a special duty to help and care for family members.

Loyalty to one’s group. Non-zero-sum games (win-win or lose-lose situations) confer genetic survival advantages when people can coordinate to pull off a task that’s impossible to pull off alone (e.g. staving off rivals for resource access). It is no surprise, then, that we value loyalty and despise traitors and cheaters. Moral values placed on loyalty oil the wheels of coordinating tasks within one’s community—tasks that benefit the self as well as others.

Reciprocity. One element of cooperation is being able to give a resource away with the trust that the value of that resource will be returned in exchange. Maintaining this ‘tit-for-tat’ expectation involves moral principles that weed free-riders out of the community. Moral capacities like gratitude, trust, anger, retribution, guilt, and apology and forgiveness facilitate social exchanges that generally boost genetic fitness.

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Heroism. When living in social groups, and dealing with scarce resources, it is inevitable that conflicts over goods will occur. Given that not everyone can get what they want, it is in the interest of the genes of all parties to settle the conflict without resorting to costly, violent acts. One way of resolving conflicts before they occur is to size up who is likely to win in the first place, and to defer to that person. Values regarding signals of ability to prevail in conflicts include heroism, confidence, skillfulness, etc.

Deference. Likewise, we would anticipate the evolution of morals involving deferring to obviously superior parties. Here, we find that indeed, people value qualities such as humility, obedience, and respect.

Dividing goods fairly. Dividing limited resources while mitigating costly conflicts can also be bolstered by shared agreement on how such resources ought to be divided from the outset. Indeed, people seem to have two general first-principles they work form on how to divide limited resources. The first involves the evolved sense of fairness or justice. People want goods to be divided equally, or equitably according to the amount of effort exerted in guaranteeing access to the resource.

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Possession. A second principle that aids in the peaceful distribution of limited resources is the sense of ownership or property rights. People around the globe tend to honor that prior possession means that a person gets continued access to the resource. Hence, we have a sense of property rights, and feel wronged when items we feel we own are stolen.

Understanding morality through the lens of game theory sheds light not only on the array of moral principles with which people operate, but also on why we can feel so morally conflicted. Sometimes, allocating extra attention and time to our struggling siblings will aggravate our desires for reciprocity. Our superiors might take too much credit for our hard work—and we’re left not knowing whether to humbly defer to them, or whether we’re too protective of our work to let the superior steal the credit. The best course of action isn’t always obvious, even from a genetic perspective.


Curry, O. S. (2016). Morality as cooperation: a problem-centered approach. In The evolution of morality. T. K. Shackelford and R. D. Hansen, eds. Pp. 27–51. New York: Springer.

Curry, O. S., Chesters, M. J., & Van Lissa, C. J. (2019). Mapping morality with a compass: Testing the theory of ‘morality-as-cooperation’with a new questionnaire. Journal of Research in Personality, 78, 106-124.