In this paper, Hayden describes patterns of preferences that seem intuitive, and that characterise many real-world agents, but that deviate from orthodox normative decision theory. These preferences even deviate from the various less orthodox decision theories designed to accommodate risk aversion. Such preferences instead exhibit regret aversion: roughly, a preference for one's chosen option to turn out better (or perhaps a lot better) than its alternatives would have.

Is regret aversion irrational? Perhaps. Hayden suggests that, especially in moral decision-making, it has a compelling motivation: it can reflect a partial concern for doing what is objectively best. But accommodating regret aversion, in the moral context or elsewhere, has its costs. Indeed, it turns out that these same costs apply to any plausible attempt to have partial concern for objective betterness.