Treatise on Law

Treatise on Law is Thomas Aquinas' major work of legal philosophy.

Aquinas defines a law as "an ordinance of reason for the common good, made by him who has care of the community, and promulgated.

[4] It is made by the proper authority who has "care of the community", and not arbitrarily imposed by outsiders.

He says: Thus from the four preceding articles [of Question 90], 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.

The Treatise on Law deals with Aquinas view’s on the objective ethical aspect of human decision-making.

Aquinas believes that reason is the first thing human acts upon; “the source in any kind of thing is the measure and rule of that kind of thing…and so we conclude that law belongs to reason.” The second is on law's relation to the common good.

The first article asks "Is the Effect of Law to Make Human Beings Good?"

“Therefore, since virtue makes those possessing it good, the proper effect of law is consequently to make its subject good, either absolutely or in some respect.” The second article of Question 92 is "Whether the acts of law are suitably assigned?"

Human beings participate in eternal law in two ways: by action and by cognition.

William S. Brewbaker III has called it "perhaps the most famous of metaphysical legal texts”,[13] while Robert M. Hutchins declared it “that greatest of all books on the philosophy of law”.