A conception of the good is “an ordered family of final ends and aims which speciies a person’s conception of what is of value in human life or, alternatively, of what is regarded as a fully worthwhile life” (JF 19). In justice as fairness, every citizen is assumed to have some conception of the good, some system of ends, aims, convictions, commitments and projects that provides the structure of values within which they make their decisions and plans. The idea of a conception of the good is tied to the Rawlsian idea of a rational plan of life. One’s rational plan of life determines – or reveals – one’s conception of good. That plan which one would select under ideal deliberative conditions, including full information about the consequences of one’s choices and about one’s own preferences, determines one’s overall system of inal ends and one’s conception of the good.

The idea of a conception of the good is also related to the idea of a comprehensive doctrine. A comprehensive doctrine includes conceptions of what is of value in human life, ideals of personal character, of friendship and family, and much else; a doctrine is fully comprehensive if it ranges over and systematizes all recognized values and virtues. After TJ, Rawls describes one’s conception of the good as embedded within one’s comprehensive (or partially comprehensive) religious, philosophical, or moral doctrine, which provides the resources to develop such a conception and “in the light of which the various ends and aims are ordered and understood” (JF 19). In deliberation, one’s comprehensive doctrine together with facts about the world and one’s own preferences and desires are taken into account, resulting in a commitment to some particular ordered system of ends.