Beginning with the Dewey Lectures (“Kantian Constructivism in Moral Theory” (1980) in CP), Rawls distinguishes between the reasonable and the rational. The reasonable is a particular form of practical rationality, but it is not always easy to understand what distinguishes it from the rational. At times it seems that the reasonable is the broader category: Rawls explains that a course of action may be rational in the sense of being in a person’s narrow interest, but nonetheless unreasonable because unacceptable to others (LHMP 164). At other times, however, it seems that the rational is the broader category: especially in PL, the principles of justice are said to be merely reasonable, not rationally justified in some deeper sense. How can we make sense of these distinctions?

In TJ, Rawls writes that his contractarian theory of justice “conveys the idea that principles of justice may be conceived as principles that would be chosen by rational persons, and that in this way conceptions of justice may be explained and justified. The theory of justice is a part, perhaps the most significant part, of the theory of rational choice” (TJ 3, 16). This striking claim was soon subject to severe criticism, and Rawls eventually abandoned it (PL 53 n.7). Even in TJ, it is clear that Rawls is operating with more than one conception of rationality, and much of his later work is devoted to clarifying their differences.