Ever since encountering Thomas Aquinas’s arguments for the existence of God in his Summa Contra Gentiles when I was a young man, I’ve been impressed by his work. Thus when I acquired Great Books of the Western World, I was pleased to find that it contained his other masterpiece, Summa Theologica. (However I was disappointed that it didn’t also contain John Calvin’s The Institutes of the Christian Religion, an omission that was rectified when the set was later expanded.) I still respect Summa Theologica, but I don’t use it as much as I use some of my other systematic theologies, its being much older than them (it was written in 1267-73) and from a Roman Catholic perspective, its being somewhat difficult to read (see below), and its seeming to treat Aristotle (“the Philosopher”) and Augustine as being as authoritative as the Bible.
In their The Development of Political Theory and Government (volume 2 of The Great Ideas Program, Encyclopedia Britannica, 1959), Mortimer J. Adler and Peter Wolff consider part of “Treatise on Law” in Summa Theologica. They consider questions 90-97, which deal with law in general, eternal law, natural law, and human law, but not questions 98-108, which deal with the law of the Old Testament and the law of the New Testament. Here I’ll give Aquinas’s definitions of law, eternal law, natural law, and human law and summarize what he discusses about each. I’ll also note and comment on the two reasons which Adler and Wolff give for most people’s finding Summa Theologica difficult to read.
“Law” is “a rule and measure of acts, by which man is induced to act or restrained from acting” (vol. 20 of Great Books of the Western World, Encyclopedia Britannica, 151, page 205). Aquinas discusses the essence of law, the kinds of law, and the effects of law. Under the essence of law he considers whether it is something pertaining to reason, whether it is always directed to the common good, whether the reason of any man is able to make laws, and whether promulgation is essential to a law. Under the kinds of law he identifies eternal law, natural law, human law, Divine law (which he divides into the Old Law and the New Law), and the law of sin. Under the effects of the law he considers whether the effect of law is to make men good and whether the acts of law are suitably assigned as consisting in command, prohibition, permission, and punishment.
“Eternal law” is “the Divine Reason’s [eternal] conception of things” (page 208). Aquinas discusses what eternal law is, whether it is known to all, whether every law is derived from it, whether necessary things are subject to it, whether natural contingents are subject to it, and whether all human beings are subject to it.
“Natural law” is “the rational creature’s participation in the eternal law” (page 209). Aquinas discusses what natural law is, what its precepts are, whether all acts of virtue are prescribed by it, whether it is the same in all, whether it is changeable, and whether it can be abolished from the heart of man.
“Human law” consists of “particular determinations, devised by human reason … provided the other essential conditions of law be observed” (page 210). Aquinas discusses it in itself, its power, and its mutability. In his discussion of human law in itself he considers the usefulness of laws framed by men, the derivation of human laws from natural law, the quality of human law, and the division of human law. In his discussion of the power of human law he considers whether it should be framed in a general way rather than for a particular case, whether it should repress all vices, whether it should direct all acts of virtue, whether it binds men in conscience, whether all men are subject to it, and whether those who are under a law may act beside the letter of the law. In his discussion of change in laws he considers whether human law is changeable, whether it should always be changed whenever anything better occurs, whether custom can obtain the force of law or abolish a law, and whether the rulers of the people can dispense from human laws.
As Adler and Woolf observe, Summa Theologica was written for the instruction of beginners but most people find it difficult to read. Adler and Woolf give two reasons, the first being that although the “beginners’ whom Aquinas had in mind were beginners in theology they were also university students with good training in the liberal arts. Related to this difficulty are Aquinas’s numerous references to writers not familiar to or accessible by most modern readers.
The second reason which Adler and Woolf give is the structure of the articles into which Summa Theologica is divided:
– a title; for example, the title for the first article in “treatise of Law” is “Whether Law Is Something Pertaining to Reason”
– an “It would seem” statement indicating the opposite of Aquinas’s conclusion; for example, the statement for the first article in “Treatise on Law” is “It would seem that law is not something pertaining to reason”
– three or four arguments in favour of the “It would seem” statement; Aquinas calls them “objections” because they are opposed to his view
– an “On the contrary” statement usually containing quotations from one or more authorities stating a view contrary to the “It would seem” statement
– a lengthy “I answer that” section arguing for Aquinas’s view
– replies to the objections, usually one for each objection
Adler and Woolf recommend reading the “I answer that” section before reading the objections and reading the replies to the objections with the objections. Although following their advice would likely make following Aquinas’s discussion, I still read his presentation in the order in which he gives it.