Contractualist tendencies and reasoning in moral judgment and decision making.

The social-contract tradition of Hobbes, Rousseau, Kant, and Rawls has been widely influential in moral philosophy but has until recently received relatively little attention in moral psychology. For contractualist moral theories, ethics is a matter of forming, adhering to, and enforcing (hypothetical) agreements, and morality is fundamentally about acting according to what would be agreed by rational agents. A recent psychological theory, virtual bargaining, models social interactions in contractualist terms, suggesting that we often act as we would agree to do if we were to negotiate explicitly. However, whether such contractualist tendencies (a propensity to make typically contractualist choices) and forms of reasoning (agreement-based cognitive processes) play a role in moral cognition is still unclear. Drawing upon virtual bargaining, we develop two novel experimental paradigms designed to elicit incentivized decisions and moral judgments. We then test the descriptive relevance of contractualism in moral judgment and decision making in five preregistered online experiments (n = 4103; English-speaking Prolific participants). In the first task, we find evidence that many participants show contractualist tendencies: their choices are "characteristically" contractualist. In the second task, we find evidence consistent with contractualist reasoning influencing some participants' judgments and incentivized decisions. Our findings suggest that a propensity to act as prescribed by tacit agreements may be particularly important in understanding the moral psychology of fleeting social interactions and coordination problems. By complementing the rich literature on deontology and consequentialism in moral psychology, empirical approaches inspired by contractualism may prove fruitful to better understand moral cognition.