1745. The Three Species of Justice.—The subjective parts of a virtue are those that partake of its essence and that are the subordinate species into which it may be distinguished, as prudence is divided into individual, domestic and political (see 1639). There are three species of justice, and their division is taken from the threefold relation that exists in a whole.
(a) Thus, legal justice directs the parts to respect the rights of the whole, and it is exercised by all those who promote the common good of a society by fulfilling well the duties which pertain to their position and rank in the society.
(b) Distributive justice regulates the whole in reference to the parts, and it is exercised by all those who seek for such a distribution of the common things of a society as accords with the inequalities of merit and ability of the members. Hence, distributive justice is found not only in the heads of a state, or family, or other body, but also in the subordinates who are content with the fair distributions made by the heads.
(c) Commutative justice orders the relations between the parts, and it is exercised by all who practise fair dealing with their equals, that is, by states with states, families with families, societies with like societies, individuals with individuals; or with those who act as their equals, as when a society acting as a moral person makes a contract with one of its members as another moral person.
1746. Resemblance between Distributive and Commutative Justice.—The general likeness between distributive and commutative justice may be summed up as follows:
(a) they have the same remote matter, since both alike are concerned with external things, persons or works. Thus, things such as goods of fortune may be distributed by the community to its members, or may be exchanged by individuals between them; labors to be performed may be assigned by the community or may be agreed on by private persons through contract;
(b) they have the same general form, since both alike seek to impress equality on the matter with which they deal, by rendering in these things to every one his due, and by making man’s actions towards his neighbor to follow the mean of reason and of the thing (see 1711).
1747. The Special Differences between Distributive and Commutative Justice.—(a) They differ in their proximate matter, that is, in the operations by which use is made of external things, persons or works; for while distributive justice acts through distribution (or division), appointment, or assignment among many, commutative justice acts through exchange, or transfer from one to another between two persons.
(b) They differ in their special form; for distributive justice seeks equality and the golden mean, according to proportion, while commutative justice seeks the same according to quantity (see 1712). Distributive justice does not treat parties as equals, but gives to each one according to his personal worth—to the more deserving the superior positions and high salaries, to the less deserving the inferior positions and lower salaries. Commutative justice, on the other hand, treats the parties as equal, and decrees that debts must be paid and injuries repaired, even though payment or reparation must be made by a good man to a bad man, and that the recompense must equal the difference created between the parties by the debt or the injury.
1748. Commutations of Commutative Justice.—There are various kinds of commutations or exchanges used by commutative justice, but they do not create new species of justice, since they are only accidental modes of the act of giving the equivalent of what one receives. They are classified as follows: