Reply to Objection 2: Actions are indeed concerned with particular matters: but those particular matters are referable to the common good, not as to a common genus or species, but as to a common final cause, according as the common good is said to be the common end.
Reply to Objection 3: Just as nothing stands firm with regard to the speculative reason except that which is traced back to the first indemonstrable principles, so nothing stands firm with regard to the practical reason, unless it be directed to the last end which is the common good: and whatever stands to reason in this sense, has the nature of a law.
Whether the reason of any man is competent to make laws?
Objection 1: It would seem that the reason of any man is competent to make laws. For the Apostle says ( Rom. 2:14 ) that "when the Gentiles, who have not the law, do by nature those things that are of the law . . . they are a law to themselves." Now he says this of all in general. Therefore anyone can make a law for himself.
Objection 2: Further, as the Philosopher says (Ethic. ii, 1), "the intention of the lawgiver is to lead men to virtue." But every man can lead another to virtue. Therefore the reason of any man is competent to make laws.
Objection 3: Further, just as the sovereign of a state governs the state, so every father of a family governs his household. But the sovereign of a state can make laws for the state. Therefore every father of a family can make laws for his household.
On the contrary, Isidore says (Etym. v, 10): "A law is an ordinance of the people, whereby something is sanctioned by the Elders together with the Commonalty."
I answer that, A law, properly speaking, regards first and foremost the order to the common good. Now to order anything to the common good, belongs either to the whole people, or to someone who is the viceregent of the whole people. And therefore the making of a law belongs either to the whole people or to a public personage who has care of the whole people: since in all other matters the directing of anything to the end concerns him to whom the end belongs.
Reply to Objection 1: As stated above (A[1], ad 1), a law is in a person not only as in one that rules, but also by participation as in one that is ruled. In the latter way each one is a law to himself, in so far as he shares the direction that he receives from one who rules him. Hence the same text goes on: "Who show the work of the law written in their hearts."
Reply to Objection 2: A private person cannot lead another to virtue efficaciously: for he can only advise, and if his advice be not taken, it has no coercive power, such as the law should have, in order to prove an efficacious inducement to virtue, as the Philosopher says (Ethic. x, 9). But this coercive power is vested in the whole people or in some public personage, to whom it belongs to inflict penalties, as we shall state further on (Q[92], A[2], ad 3; SS, Q[64], A[3]). Wherefore the framing of laws belongs to him alone.
Reply to Objection 3: As one man is a part of the household, so a household is a part of the state: and the state is a perfect community, according to Polit. i, 1. And therefore, as the good of one man is not the last end, but is ordained to the common good; so too the good of one household is ordained to the good of a single state, which is a perfect community. Consequently he that governs a family, can indeed make certain commands or ordinances, but not such as to have properly the force of law.
Whether promulgation is essential to a law?
Objection 1: It would seem that promulgation is not essential to a law. For the natural law above all has the character of law. But the natural law needs no promulgation. Therefore it is not essential to a law that it be promulgated.
Objection 2: Further, it belongs properly to a law to bind one to do or not to do something. But the obligation of fulfilling a law touches not only those in whose presence it is promulgated, but also others. Therefore promulgation is not essential to a law.
Objection 3: Further, the binding force of a law extends even to the future, since "laws are binding in matters of the future," as the jurists say (Cod. 1, tit. De lege et constit. leg. vii). But promulgation concerns those who are present. Therefore it is not essential to a law.
On the contrary, It is laid down in the Decretals, dist. 4, that "laws are established when they are promulgated."
I answer that, As stated above (A[1]), a law is imposed on others by way of a rule and measure. Now a rule or measure is imposed by being applied to those who are to be ruled and measured by it. Wherefore, in order that a law obtain the binding force which is proper to a law, it must needs be applied to the men who have to be ruled by it. Such application is made by its being notified to them by promulgation. Wherefore promulgation is necessary for the law to obtain its force.
Thus from the four preceding articles, the definition of law may be gathered; and it is nothing else than an ordinance of reason for the common good, made by him who has care of the community, and promulgated.
Reply to Objection 1: The natural law is promulgated by the very fact that God instilled it into man's mind so as to be known by him naturally.
Reply to Objection 2: Those who are not present when a law is promulgated, are bound to observe the law, in so far as it is notified or can be notified to them by others, after it has been promulgated.
Reply to Objection 3: The promulgation that takes place now, extends to future time by reason of the durability of written characters, by which means it is continually promulgated. Hence Isidore says (Etym. v, 3; ii, 10) that "lex [law] is derived from legere [to read] because it is written."