Randall Harp's main research areas are in the philosophy of action (particularly collective action and decision theory), in the philosophy of social and behavioral science, in social metaphysics, and in ethics (in particular data ethics). He has written on the proper characterization of individual and collective goals, on the integration of goals in models of deliberation, and on the nature of explanation in social science. He has also written on the connection between agency and metaethics in the early modern philosopher Thomas Reid.