1699. The Objects or Subject-Matter of Justice.—(a) The material object of justice (i.e., all those things with which it deals) is remotely the external things which are the objects of exchange and distribution among men, and proximately the actions by which they are exchanged or distributed.
(b) The formal object of justice (i.e., that which it principally intends in dealing with its material object) is that the rights of others, or their inviolable moral power of doing, having or acquiring, may be respected. Justice thus differs from charity. For charity is owed also to self, justice only to the neighbor; charity considers the neighbor as he is one with self and gives him what belongs to self, while justice considers the neighbor as he is distinct from self and gives him what belongs to him.
1700. Since justice is shown not to self but to another, it is not so fully-realized when two persons are in some sense one.
(a) Parent and child are especially one, since the child is from the parent and a part of the parent, and hence the natural obligations that spring from their special relationship pertain to the virtue of filial and paternal piety, which is not strictly justice, but obliges more strictly on account of the greater rights involved. But obligations that spring from relationships that are common (e.g., from a contract between a father and his son) pertain to strict justice; for in these relationships they treat with one another, not as father and son, but as man and man. Employer and employee may also be considered as one, inasmuch as the latter is the agent or instrument of the former, and the same conclusions may therefore be applied to them.
(b) Husband and wife are less perfectly one than parent and child and than master and servant, for neither is descended from the other, and neither is servant to the other. But since they form one conjugal society and the husband is head of the wife, they owe one another stricter obligations than if they were strangers to one another, although those obligations partake less rigorously of the character of justice.
1701. Division of Justice.—Justice is divided according to the rights it respects into legal and particular. (a) Legal justice (observance of law) is that which is owed by the individual, whether he be ruler or subordinate, to the community of which he forms a part, or to the law and the common good of the entire body. (b) Particular justice (fairness) is that which is owed to the private good of an individual.
1702. Is legal justice a distinct and separate virtue, or only a general condition found in all virtues?
(a) Practically speaking, legal justice is a general virtue, inasmuch as its desire of promoting the common good will impel a man to observe all the laws and to practise other virtues than justice, such as fortitude and temperance. The law commands us to perform the actions of the courageous man, of the temperate man, of the gentle man, and hence, as Aristotle says (_Ethics_, lib. V, cap. 2), legal justice is often regarded as the supreme virtue, the summary of all virtue, more glorious than the star of eve or dawn.
(b) Essentially, it is a distinct virtue, for it alone moves a man primarily and directly to respect the rights of the common good as being that greater whole of which the individual is but a part. It differs even from patriotism and filial piety (for these are moved by one’s own debt to the source of one’s life) and from obedience (for legal justice seeks the welfare of the community even in things that are not commanded).
1703. Comparison of Legal and Particular Justice.—(a) Particular justice partakes more of the nature of justice, for there is a greater distinction or separation between the party who has an obligation and the party who has a right, when the latter is an individual, than when the latter is a whole of which the former is a part. A distinctive characteristic of justice, as said just above, is that it takes account of the independence or “otherness” of those between whom it exists, so much so that only in a metaphorical sense can we speak of justice when only one person and nature is in question (e.g., justice between man and his soul, body, powers).