Article I: On the Matter of Human Law

St. Thomas, I-II, q. 96, a. 1, 2, 3.

279. Principle. Law must be proportioned to the end, which is the common good (n. 272), and therefore the matter about which civil law is concerned is all acts whose placing or omission is useful to the common good, even those which are indifferent of themselves, insofar as they can be ordered to virtue and good or to vice and evil. But the common good consists of many things: 1) for society is constituted from many persons, 2) it is ordered to a good which consists in many affairs, to be procured through manifold actions, 3) it is instituted not so that it endure for some small time, but so that it persevere for all time through the succession of citizens. Therefore law must procure the good not of some but of many, not in some one thing or action but in many, not for some time but in a mode of itself perpetual.

280. Acts useful to the common good are only:

1. Acts morally possible, that is, not too difficult and burdensome, but accommodated to the powers of men (their frailty being attended to, not only in common but also according to special condition and circumstances); otherwise law would not be conformable to reason nor promote the public good, but would rather often be the occasion of sins, since it would be observed by few. Hence:

a) Heroic acts cannot be commanded, unless in extraordinary public necessity (for example, a law could command physicians in time of plague to remain in the city), or unless one has freely chosen a state to which they pertain.

b) Although law can prohibit any vices whatsoever, nevertheless not all simultaneously, or all vicious acts: for law must be imposed upon a multitude of men according to their condition in such a way that it is possible for them; but in a multitude the greater part is of the imperfect, and therefore not all vices are prohibited, but only the graver ones, from which it is possible for the greater part of the multitude to abstain, and chiefly those which harm others, such as homicide, thefts, etc., without whose prohibition society could not be preserved.

2. Acts external in some way: for by these alone does man bear himself well or badly toward others constituting the city, for society arises from external relations; whence external acts alone, and not merely internal acts, are directly necessary or useful to the end, which is peace, by which citizens can tranquilly use their rights, and public prosperity.

Nevertheless internal acts can be commanded indirectly and per accidens, insofar as they are joined with external acts and manifested by them, for example, if they are necessary that external acts be human, good, not feigned, etc.; for law cannot command except morally good acts.

3. Future acts, whence it is said: Law does not have eyes backward, and "La loi ne dispose que pour l'avenir; elle n'a pas d'effet rétroactif" (Civil Code, a. 2).

Thus a) according to directive force: for since law is a rule of things to be done, by its nature it regards future acts, not past acts, which cannot be ruled; namely, to command, prohibit, permit past acts, or, if they are irrevocable, invalidate them, would be useless. Likewise b) ordinarily also according to coercive force: because, namely, it is very odious, past acts regularly cannot be punished, nor acts still revocable be invalidated, unless they have already been prohibited by some law, or on account of a great necessity of the common good; for in this case whatever good of the part can be required for the good of the whole, but it will rather be the imposition of a burden than of a penalty. Hence the legislator cannot affect past acts except a) in a penal law which imposes a penalty on an act already prohibited (at least by natural right); b) in a law establishing not a penalty but an inability, if the reason of the common good demands it; c) in a merely declarative law of an earlier law.

281. The common good is manifold:

1. One thing civil society immediately intends, namely, its own and its members' temporal perfection and happiness, that is, to establish a good life in the multitude, to preserve it, and by promoting it to better things to perfect it. To this pertain both the goods of society itself: constitution, regime, administration, defense, and the relations of citizens to it and among themselves; and the goods of the members: a) goods of the intellect: instruction in letters, sciences, and human arts (which greatly contribute to private and public good); b) goods of the will: to coerce delicts, attack vices, and promote virtues, indeed all of them: for all virtues whatsoever, just as they can be referred to private good, so also to the common good, just as all vices can be opposed to it, and therefore there is no virtue concerning whose acts law cannot command. Yet it does not command concerning all acts of all virtues, but only concerning those which are orderable to the common good, either immediately, as those which are done directly on account of the common good, or mediately, as certain things are ordered by the legislator to good discipline, by which citizens are formed so that they may preserve the common good of justice and peace. Hence human law commands only acts of justice, and acts of the other virtues insofar as they assume the notion of justice; c) goods of the body: public health and due propagation; d) goods of fortune and those things which concern the acquisition, transmission, abundance of things, industries, agriculture, and commerce.

2. Another thing society intends only mediately, namely, eternal beatitude; and therefore, although it ought to procure temporal goods in such a way that they do not harm eternal goods, indeed so that they procure them, nevertheless it cannot bear law immediately concerning spiritual things; nor concerning mixed things except in concord with religious society.

282. Observation.

In all the aforesaid matters it can either inculcate natural and divine law, for example, by compelling parents to nourish minor children, and children to provide food for parents; or determine what that law leaves indeterminate, for example, by establishing conditions for succession in the goods of the dead or the mode of exercising justice; or impose what is more conformable to it, for example, prescription of goods, community or separation of goods in marriage, rescission of a contract begun by minors; or command or prohibit what that law permits, for example, concerning fishing, the manufacture of liquors, or hunting; or urge all these things by adding a penalty; or even impose conditions for the validity of acts established by it (for example, concerning contracts); nevertheless in no way can it contradict a superior law.