Moral Psychology: Research on How People Make Ethical Judgments

Moral psychology is the scientific study of how people think, feel, and behave in domains involving right and wrong, harm and fairness, care and purity. Research in this area has grown significantly since the 1990s, drawing on experimental psychology, developmental research, neuroscience, and cross-cultural study. The findings have substantially complicated earlier rationalist models of moral judgment and have significant implications for how we understand ethical behavior, moral disagreement, and the possibilities for moral education. Lawrence Kohlberg's stage theory of moral development, which proposed that moral reasoning develops through invariant stages from preconventional concerns about punishment and reward through conventional concern for social norms to postconventional reasoning based on universal principles, was the dominant framework in moral psychology for decades. Research on Kohlberg's theory has found that the stage model overstates the consistency and universality of moral reasoning, that cultural variation in moral priorities is significant, and that the model reflects a particular Western, educated, individualistic orientation toward morality rather than a universal developmental sequence. Jonathan Haidt's social intuitionist model, proposed in a widely cited 2001 paper, offers a different account of moral judgment that has generated substantial research. Haidt proposed that moral judgments arise primarily from rapid intuitive responses rather than from deliberate reasoning, and that moral reasoning typically functions as post-hoc rationalization of judgments that have already been made intuitively. Research supporting this view includes studies showing that people make moral judgments quickly, that these judgments are influenced by factors irrelevant to the moral logic of situations, and that people have difficulty providing coherent reasoning for their judgments in certain cases. The moral foundations framework, developed by Haidt and colleagues, proposes that moral intuitions cluster around several distinct psychological systems: care and harm, fairness and reciprocity, loyalty and betrayal, authority and subversion, purity and degradation, and liberty and oppression. Research using surveys and experimental methods finds that different individuals and political groups show different patterns of sensitivity across these foundations, with politically liberal individuals showing stronger prioritization of harm and fairness relative to the other foundations, while politically conservative individuals show more balanced sensitivity across all foundations. This finding has been interpreted as illuminating the moral basis of political disagreement. Trolley problems and related philosophical thought experiments have been used extensively in moral psychology research to probe moral intuitions. Research using these dilemmas finds that people typically react with emotional reluctance to personally harmful actions even when those actions produce the greater good, and that this reluctance is reduced when harmful actions are more physically removed or abstract. Neuroimaging research finds different brain activation patterns for personally violent versus impersonal versions of moral dilemmas, consistent with the claim that emotional systems are differentially recruited depending on the personal nature of the harm. Disgust has received research attention as a moral emotion that influences ethical judgments in ways that may not always be morally relevant. Research on the relationship between physical disgust and moral judgment finds that inducing disgust through unrelated means, such as exposure to bad smells, increases the severity of moral judgments on unrelated moral scenarios. This finding has been interpreted as evidence that the emotion of disgust, originally evolved for protection from physical contaminants, has been co-opted in moral psychology to generate intuitions about purity and contamination violations. The moralization of disgust may produce judgments that are difficult to justify on rational grounds. Cross-cultural research on moral psychology has complicated claims about universal moral foundations. Research comparing responses to moral dilemmas and moral priorities across culturally diverse populations, including the WEIRD population critique discussed in other research contexts, finds significant variation in moral intuitions and priorities. Individualistic versus collectivist orientations affect how people weight individual rights against collective welfare. Cultural variation in the importance of purity and loyalty norms is substantial. This cross-cultural variation challenges claims about innate universal moral foundations and supports the view that moral intuitions are shaped significantly by cultural learning. The practical implications of moral psychology research for ethical education are contested. If moral judgments arise primarily from intuition rather than reason, then moral education that focuses exclusively on developing reasoning skills may be insufficient. Research on moral education programs that engage both emotional and rational dimensions of morality, that work to cultivate emotional sensitivities alongside critical reasoning, and that attend to the social and cultural contexts that shape moral intuitions show better outcomes for moral behavior than those focused exclusively on cognitive moral reasoning development.