This article challenges the received view on the role of motivations in contemporary theories of social justice. Neo-Kantians argue that a theory of justice must be rooted in moral motivations of reasonableness, not rationality. Yet reasonableness is a demanding motivation, stipulating actions that people may not be able or willing to perform. This opens egalitarians like Rawls to the accusation of prescribing a political philosophy that is not 'followable'. The aim of this article is to explore the benefits for egalitarian (...) theories of justice of sanctioning both rational and reasonable motivations. Being vulnerable to self-regarding passions, people often fail to act upon the principles of fairness or impartiality, even when they are motivated by their sense of justice. The institutions of justice must therefore find a way to fortify and encourage the development of our sense of justice. This can be achieved by giving people a rational incentive to act upon and therefore engender their sense of justice. Finding ways to motivate people to act justly is the most pressing challenge facing egalitarian justice today. (shrink)