 Subsequent to A Theory of Justice, in Kantian and Political Constructivism, Rawls says that the parties to the original position have a “higher-order interest” in the exercise and development of their capacity for a sense of justice (as well as in their capacity to be rational), and that fulfilling this interest is one of the main aims behind their agreement on principles of justice. The parties’ interest in developing these two “moral powers” is a substantive feature of Rawls’s account of the rationality of free and equal persons. (In this regard, his account of goodness as rationality is not as “thin” as in social theory; cf. TJ 143/124.) Here is it is important to see that Rawls is still not attributing specifically moral motives—a desire to be reasonable and do what is right and just for their own sake—to the parties in the original position. The idea behind the parties’ rationality in cultivating their sense of justice is that, since reasonableness is a condition of human sociability and social cooperation, then it is in people’s rational interest—part of their good—that they normally develop their capacities for justice under social conditions. Otherwise they will not be in a position to cooperate with others and benefit from social life. A person who is without a sense of justice is wholly unreasonable and as a result is normally eschewed by others, for he or she is not trustworthy or reliable or even safe to interact with. Since having a sense of justice is a condition of taking part in social cooperation, the parties have a “higher-order interest” in establishing conditions for the full development and effective exercise of their capacity for a sense of justice. The parties’ interest in developing their capacity for a sense of justice is then a rational interest in being reasonable; justice is then regarded by the parties as instrumental to their realizing their conception of the good. (Here again, it is important to distinguish the purely rational motivation of the parties or their trustees in the original position from that of free and equal citizens in a well-ordered society, who are normally morally motivated by their sense of justice to do what is right and just for its own sake.)