What motivates individuals to engage in collective action? Moral responsibility, not causal responsibility, drives voting

Why do people engage in collective behaviors (such as voting) for which their individual, causal contribution is likely to be negligible? We examined whether human action beliefs (i.e., believing that moral progress is caused by human actions) predict voting behavior and whether this relationship is mediated by moral responsibility (do I have a moral obligation to vote?) and causal responsibility (does my vote make a difference?). In Study 1a (N = 356), conducted one week before the 2024 US presidential election, we found that human action beliefs predicted voting intentions, and this relationship was fully mediated by responsibility. In Study 1b (N = 287), conducted one day after the election, human action beliefs predicted actual voting only indirectly via responsibility, and moral responsibility, not causal, drove this effect. Study 2 (N = 935) replicated these results, again finding that moral responsibility, but not causal responsibility, predicted voting. In Study 3 (N = 309), we experimentally manipulated moral and causal responsibility in a hypothetical election. Moral responsibility, but not causal responsibility, predicted voting intentions. Across our studies, both observational and experimental, moral responsibility emerged as the strongest and most consistent psychological predictor of voting behavior, regardless of whether individuals felt that their vote would make a difference. These findings suggest that promoting a sense of moral responsibility might be key to increasing voter turnout and other forms of collective action. They also suggest the theoretical importance of differentiating moral and causal notions of responsibility.