The articles of this section deal merely with whether the definition of law fits the four kinds of laws commonly identified: eternal, natural, divine and human. Thomas leaves the a more in-depth description of these types of laws for later.

Eternal Law: "The whole community of the universe is governed by Divine Reason," which has the nature of a law which is not subject to time and is unchanging.

Such continuous intervention, such presence of God in the most material things is hard to fathom in the afterglow of the Enlightenment project. "The God of the deists ... is decidedly a God outside of the world... The rationalism of the Enlightenment was able to accept a God outside of the world primarily because it was an unverifiable hypothesis. It was crucial, however, that such a God be expelled from the world." John Paul II, Crossing the Threshold of Hope, "What Has Become of the 'History of Salvation'?"

Let's take a closer look at providence I 22 Articles 1 and 2 to which Thomas refers in his response:

All things are subject to divine providence, not only in general, but even in their own individual selves. I 22, 2

Providence is the "notion of things ordered towards an end", (I 22.1) it is care for the future. Providence is "the chief part of prudence," the other parts being "remembrance of the past and understanding of the present, inasmuch as from the remembrance of what is past and the understanding of the present, we gather how to provide for the future." (I 22.1) It belongs to prudence "to direct other things towards an end whether in regard to oneself or to others subject to him." I 22.1

Now prudence and providence can be attributable to God who is the efficient cause (creator) of all things. "Hence, all things that exist in whatsoever manner are necessarily directed by God towards some end." I 22.2

Natural Law: natural law is "the peculiarly human way of participating in the eternal law whereby God governs the universe. The rational creature directs himself to his appropriate end and activity." Ralph McInerny, Ethica Thomistica, 1996, Chapter 3 "Ultimate End and Moral Principles"

"All things partake somewhat of the eternal law." By its being imprinted on them (imprinted is the same verb Thomas will use with respect to human law (I II 93,5)) all things "derive their respective inclinations to their proper act and ends…All that is in things created by God is subject to the eternal law" (I II 93.4). Irrational creatures participate in the eternal law from which they derive their natural inclinations to their acts and end. They enjoy providence but do not participate in it. Natural law, strictly speaking, is reserved for the rational creature.

The rational creature, man, participates in divine providence, is "subject to divine providence in the most excellent way", by being provident for, taking care of, itself and others. This participation in the eternal law is called the natural law. Both the speculative and practical reason participate in the Divine Reason but only the practical reason's participation is called natural law (I II 91.3, ad 1). Natural law is not something different from eternal but a participation in it (I II 91.2, ad 1).

In other words, God not only designed human nature, as distinct from plant nature and animal nature, but He imprinted on it the operating instructions which make themselves known to the practical reason.

Thomas's classic definition of law "an ordination of reason, for the common good, by the legimate authority and promulgated" I II 90,4 might not, at first glance, seem to fit natural law Let's take a look at the component parts in order to get the full essence of natural law.

An ordination of reason by the legitimate authority: God is the designer of the cosmos and the rule and measure of the eternal law which is imprinted on human nature. Therefore man participates in the divine government of the cosmos according to his nature, in an "intellectual and rational manner", in a "most excellect way" than the rest of creation which participates only passively in full submission to the eternal law. The "most excellent way" is an active participation in the eternal law, in the providence of God whereby man is "provident for himself and others". Man participates as ruler and man's reason, imprinted with the natural law, serves as the rule and measure. Man is the ruler in the sense of a subgovernor who is entrusted with the law of his superior and passes it on to his subject (himself and others).

For the common good: The rational creature must take care of itself and others and even such a private good as self-management contributes to the common good.

Promulgation: The requirement of promulgation is satisfied by the imprinting of the law on nature:

The impression of an inward principle is to natural things, what the promulgation of law is to men: because law, by being promulgated, imprints on man a directive principle of human actions. I II 93,5 ad 2

Human Law: Natural law, a participation of the eternal law on the part of the practical reason, is only concerned with the most fundamental general principles. In order to make "particular determinations of individual cases" the human reason needs to proceed from the precepts of the natural law "to the more particular determination of certain matters". Each person does this for himself and the proper authority does it for the community by issuing laws.

"Human laws cannot have that inerrancy that belongs to the demonstrated conclusions of science" (I II 91.3, ad 3). The conclusions of speculative reason, the conclusions of science, can continue to bump into eternal laws as they move outwards from the first principles, but the conclusions of the practical reason immediately start to lose their integrity as they move from the first principles.

The important point is the continuity between the eternal law, natural law and human law.

Divine law: This is the law of God promulgated in history, i.e. the ten commandments, the eight beatitudes, the commandment of love. The question is not whether there is a divine law but whether it was necessary and Thomas gives four reasons why it was necessary. The first is that man has a supernatural end which is beyond the power of human reason to comprehend, therefore, man needed to be directed to his end by a law given by God. This was Aristotle's problem with eudaimonia. He probably went as far as anyone could merely with human faculties.

The second arguement for the necessity of divine law is "on account of the uncertainty of human judgement". The content of the divine law is not limited to matters beyond our natural faculties. There is a great deal of overlap between divine law and natural law, but we see around us a lot of anguish caused by contradictory advice to the question "What should I do?", therefore, Thomas finds divine law necessary.