The study of justice and injustice has three main elements: (a) determination of the kind of actions that come within the scope of each, (b) determination of what kind of mean justice is, (c) determination of the extremes between which justice is to be found.
The word justice has two main definitions — that which is lawful and that which is fair and equal. These may be termed respectively, "universal" justice and "partial" or "particular" justice. Universal justice is co-extensive with virtue, in that the virtuous man obeys the law, but this presupposes that the law is based on virtue. Universal justice is slightly different from virtue, however, in the sense that it is concerned with relations between people and institutions and not between people and people. Since it pertains to the question of social justice, universal justice is best deferred until we begin our study of politics and political institutions.