Preparatory to his argument that justice, as understood within justice as fairness, is congruent with the good and happiness of those it governs, Rawls examines a family of closely related ideas: happiness, a rational life plan, a dominant end, hedonism, and the unity of the self. More speciically he considers and rejects a number of claims involving these ideas so as to set the stage for the place and content of these ideas within the so-called congruence argument he presents in favor of justice as fairness. One of the claims he considers and rejects is that without appeal to a dominant end to which rational persons subordinate all their other ends we cannot give meaningful content to the idea of a person’s happiness in order to consider how justice may be related to it. Another is that we cannot account for the unity of the persons whose happiness we must show to be congruent with justice without appeal to a dominant end.

A person is happy, Rawls argues, when she is successfully carrying through her rational plan for her life and is conident that she will continue to be successful in her future efforts. Since her rational plan speciies her good, a person is happy when her good is realized and she is reasonably optimistic that it will continue to be so. Her plan for her life, which may be more or less developed, is given by her various ends. It is a rational plan insofar as it is both (i) a coherently ordered system of ends, or a plan, that is consistent with the counting principles of rational choice and (ii) the plan, assuming there are many plans that satisfy the foregoing condition, that she has chosen or at least would choose with full deliberative rationality. To choose with full deliberative rationality is to choose with complete awareness of all the relevant facts and after careful consideration of the total consequences of making each of the alternative choices available.