Our goal in this paper is to use an evolutionary approach to explain the existence and design-features of human moral cognition. Our approach is based on the premise that human beings are under selection to appear as good cooperative investments. Hence they face a trade-off between maximizing the immediate gains of each social interaction, and maximizing its long-term reputational effects. In a simple 2-player model, we show that this trade-off leads individuals to maximize the generalized Nash product at evolutionary equilibrium, i.e., to behave according to the generalized Nash bargaining solution. We infer from this result the theoretical proposition that morality is a domain-general calculator of this bargaining solution. We then proceed to describe the generic consequences of this approach: (i) everyone in a social interaction deserves to receive a net benefit, (ii) people ought to act in ways that would maximize social welfare if everyone was acting in the same way, (iii) all domains of social behavior can be moralized, (iv) moral duties can seem both principled and non-contractual, and (v) morality shall depend on the context. Next, we apply the approach to some of the main areas of social life and show that it allows to explain, with a single logic, the entire set of what are generally considered to be different moral domains. Lastly, we discuss the relationship between this account of morality and other evolutionary accounts of morality and cooperation.

Why do humans develop beliefs in supernatural entities that punish uncooperative behaviors? Leading hypotheses maintain that these beliefs are widespread because they facilitate cooperation, allowing their groups to outcompete others in inter-group competition. Focusing on within-group interactions, we present a model in which people strategically endorse supernatural punishment beliefs to manipulate others into cooperating. Others accept these beliefs, meanwhile, because they are made compelling by various cognitive biases: They appear to provide information about why misfortune occurs; they appeal to intuitions about immanent justice; they contain threatening information; and they allow believers to signal their trustworthiness. Explaining supernatural beliefs requires considering both motivations to invest in their endorsement and the reasons others adopt them.

Why do many human societies morally condemn apparently victimless and pleasurable behaviors, such as lust, gluttony, drinking, drugs, gambling, or even music and dance? Why do they morally praise temperance, chastity, sobriety, decency, and piety? While this puritanical morality often appears as an exception to the cooperative function of moral cognition, we propose that it stems, like other moral concerns, from moral judgements targeting cooperative challenges. Specifically, we propose that it consists of preemptive moralizations of behaviors perceived as risk factors for uncooperative self-control failures, impeding people's ability to resist the short-term temptations naturally conflicting with cooperative motivations.

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