On Law by Thomas Aquinas
Eternal Law | Divine Law | Natural Law | and Human Law
St. Thomas on Law
St. Thomas Aquinas, in his Summa Theologica, explains that the Law is “an ordinance of reason, made and promulgated by those who are in charge of welfare of the community, to achieve the common good.”1
Law is an ordinance of reason because “the rule or measure of human act is reason; what binds a man in reference to human acts pertains to reason.”2
Law is made by those who are in charge of welfare of the community. Since law is for the common good of the society, there are two ways in which laws can be made. “It is made either by the society which it binds, or it is imposed on that society by the public personage who has charge of the society and authority to rule it.”3
Law is promulgated in the society. “It must be sufficiently announced and made known to those upon whom it lays obligation. Without the knowledge of a law, a person cannot be guided by it in his human acts.”4
Law is created to achieve the common good. “Law is not directly for the benefit of individual persons as such, although it binds individual persons. Law is primarily for the benefit of individuals in a group, in a society.”5
“Law is a rule and measure of acts, whereby man is induced to act or is restrained from acting: for lex [law] is derived from ligare [to bind], because it binds one to act. Now the rule and measure of human acts is the reason, which is the first principle of human acts, as is evident from what has been stated above (Q[1], A[1], ad 3); since it belongs to the reason to direct to the end, which is the first principle in all matters of action, according to the Philosopher (Phys. ii). Now that which is the principle in any genus, is the rule and measure of that genus: for instance, unity in the genus of numbers, and the first movement in the genus of movements. Consequently it follows that law is something pertaining to reason.”6
Reason on Law
“Reason has its power of moving from the will, as stated above (Q[17], A[1]): for it is due to the fact that one wills the end, that the reason issues its commands as regards things ordained to the end. But in order that the volition of what is commanded may have the nature of law, it needs to be in accord with some rule of reason. And in this sense is to be understood the saying that the will of the sovereign has the force of law; otherwise the sovereign’s will would savor of lawlessness rather than of law.”7
Law and the Common Good
“…the law belongs to that which is a principle of human acts, because it is their rule and measure. Now as reason is a principle of human acts, so in reason itself, here is something which is the principle in respect of all the rest: wherefore to this principle chiefly and mainly law must needs be referred. Now the first principle in practical matters, which are the object of the practical reason, is the last end: and the last end of human life is bliss or happiness, as stated above (Q[2], A[7]; Q[3], A[1]). Consequently, the law must need regard principally the relationship to happiness. Moreover,
since every part is ordained to the whole, as imperfect to perfect; and since one man is a part of the perfect community, the law must need regard properly the relationship to universal happiness. Wherefore the Philosopher, in the above definition of legal matters mentions both happiness and the body politic: for he says (Ethic. v, 1) that we call those legal matters just, which are adapted to produce and preserve happiness and its parts for the body politic: since the state is a perfect community, as he says in Polit. i, 1.
Now in every genus, that which belongs to it chiefly is the principle of the others, and the others belong to that genus in subordination to that thing: thus fire, which is chief among hot things, is the cause of heat in mixed bodies, and these are said to be hot in so far as they have a share of fire. Consequently, since the law is chiefly ordained to the common good, any other precept in regard to some individual work, must needs be devoid of the nature of a law, save in so far as it regards the common good. Therefore every law is ordained to the common good.”8
“The effect of law is to make men good. For law is an ordinance of reason; it is the function of such ordinance to direct men, through their virtue, to their true end.”9
Kinds of Law
1. Eternal Law
a law is nothing else but a dictate of practical reason emanating from the ruler who governs a perfect community. Now it is evident, granted that the world is ruled by Divine Providence, as was stated in the FP, Q[22], AA[1],2, that the whole community of the universe is governed by Divine Reason. Wherefore the very Idea of the government of things in God the Ruler of the universe, has the nature of a law. And since the
Divine Reason’s conception of things is not subject to time 10
2. Natural Law
law, being a rule and measure, can be in a person in two ways: in one way, as in him that rules and measures; in another way, as in that which is ruled and measured, since a thing is ruled and measured, in so far as it partakes of the rule or measure. Wherefore, since all things subject to Divine providence are ruled and measured by the eternal law, as was stated above (A[1]); it is evident that all things partake somewhat of the eternal law, in so far as, namely, from its being imprinted on them, they derive their respective inclinations to their proper acts and ends. Now among all others, the rational creature is subject to Divine providence in the most excellent way, in so far as it partakes of a share of providence, by being provident both for itself and for others. Wherefore it has a share of the Eternal Reason, whereby it has a natural inclination to its proper act and end: and this participation of the eternal law in the rational creature is called the natural law. Hence the Psalmist after saying (Ps. 4:6): “Offer up the sacrifice of justice,” as though someone asked what the works of justice are, adds: “Many say, Who showeth us good things?” in answer to which question he says: “The light of Thy countenance, O Lord, is signed upon us”: thus implying that the light of natural reason, whereby we discern what is good and what is evil, which is the function of the natural law, is nothing else than an imprint on us of the Divine light. It is therefore evident that the natural law is nothing else than the rational creature’s participation of the eternal law.
3. Divine Law
Besides the natural and the human law it was necessary for the directing of human conduct to have a Divine law. And this for four reasons. First, because it is by law that man is directed how to perform his proper acts in view of his last end. And indeed if man were ordained to no other end than that which is proportionate to his natural faculty, there would be no need for man to have any further direction of the part of his reason, besides the natural law and human law which is derived from it. But since man is ordained to an end of eternal happiness which is inproportionate to man’s natural faculty, as stated above (Q[5], A[5]), therefore it was necessary that, besides the natural and the human law, man should be directed to his end by a law given by God.
Thirdly, because man can make laws in those matters of which he is competent to judge. But man is not competent to judge of interior movements, that are hidden, but only of exterior acts which appear: and yet for the perfection of virtue it is necessary for man to conduct himself aright in both kinds of acts. Consequently human law could not sufficiently curb and direct interior acts; and it was necessary for this purpose that a Divine law should supervene.
Fourthly, because, as Augustine says (De Lib. Arb. i, 5,6), human law cannot punish or forbid all evil deeds: since while aiming at doing away with all evils, it would do away with many good things, and would hinder the advance of the common good, which is necessary for human intercourse. In order, therefore, that no evil might remain unforbidden and unpunished, it was necessary for the Divine law to supervene, whereby all sins are forbidden.
And these four causes are touched upon in Ps. 118:8, where it is said: “The law of the Lord is unspotted,” i.e. allowing no foulness of sin; “converting souls,” because it directs not only exterior, but also interior acts; “the testimony of the Lord is faithful,” because of the certainty of what is true and right; “giving wisdom to little ones,” by directing man to an end supernatural and Divine.
4. Human Law
A law is a dictate of the practical reason. Now it is to be observed that the same procedure takes place in the practical and in the speculative reason: for each proceeds from principles to conclusions, as stated above (De Lib. Arb. i, 6). Accordingly we conclude that just as, in the speculative reason, from naturally known indemonstrable principles, we draw the conclusions of the various sciences, the knowledge of which is not imparted to us by nature, but acquired by the efforts of reason, so too it is from the precepts of the natural law, as from general and indemonstrable principles, that the human reason needs to proceed to the more particular determination of certain matters. These particular determinations, devised by human
reason, are called human laws, provided the other essential conditions of law be observed, as stated
above (Q[90], AA[2],3,4). Wherefore Tully says in his Rhetoric (De Invent. Rhet. ii) that “justice has its source in nature; thence certain things came into custom by reason of their utility; afterwards these things which emanated from nature and were approved by custom, were sanctioned by fear and reverence for the law.
FOOTNOTES
1ST I-II, q.90. a.4.
2Paus Glenn, A Tour of the Summa: A Journey through St. Thomas Aquinas’ Summa Theologica, (Illinois: Tan Books and Publisher, Inc., 1978), 166.
3Ibid.
4Ibid.
5Ibid.
6ST I-II, q. 90. a. 1.
7ST I-II, q. 90. a. 1.
8ST I-II, q.90. a.2.
9Glenn, A Tour of the Summa: A Journey through St. Thomas Aquinas’ Summa Theologica, 167.
10ST I-II, q.91. a.1.
11ST I-II, q.91. a.2.
12ST I-II, q.91. a.4.
13ST I-II, q.91. a.3.
Read further: Thomas Aquinas on Law (wku.edu)