Ius et Iustitium is happy to present this post by Patrick Button. Mr. Button is an attorney in Orlando, Florida.
Usually when the natural law is brought up in mainstream discourse on law and morality, when it is brought up at all, it is in one of two contexts. First, the legitimacy of disobeying unjust laws, and second, debates over so-called morals legislation aimed against carnal vices. These are certainly areas where the relationship between natural law and positive law is of great importance, but the scope of that relationship is much broader. In truth, all just legislation is derived from the natural law, from the prohibition of murder to parking regulations. One might reasonably object that parking regulations are relatively arbitrary, and do not seem comparable to laws against specific and grave evils like murder. In fact there is a categorical distinction to be made, which St. Thomas explains in Question 95 of Part I-II of the Summa Theologiae.
In Article 2 of Question 95, St. Thomas asserts that human law is derived from the natural law in two ways, “first as a conclusion from premises, secondly by way of determination of certain generalities.” The first mode of derivation, per modum conclusionis, “is like to that by which, in sciences, demonstrated conclusions are drawn from the principles.” The second mode, per modum determinationis, “is likened to that whereby, in the arts, general forms are particularized as to details.” Thomas uses the example of a craftsman who must “determine the general form of a house to some particular shape,” that is, to create a specific, material building from the general idea of a house.
Thomas illustrates each mode of derivation with a concrete legal example:
Some things are therefore derived from the general principles of the natural law, by way of conclusions; e.g. that “one must not kill” may be derived as a conclusion from the principle that “one should do harm to no man”: while some are derived therefrom by way of determination; e.g. the law of nature has it that the evil-doer should be punished; but that he be punished in this or that way, is a determination of the law of nature.
IaIIae q95, a2.
The legal principle that one must not kill, i.e., the legal prohibition of homicide, is derived directly as a conclusion from the natural law. In contrast, the particular regime under which a criminal is punished, for murder or any other crime, is less proximate to the natural law, while nevertheless being derived from it.
This is where parking regulations come in. Natural law principles relating to the just use of the material world according to its ends can be “determined” into a system that limits the times and places that you may park your car. Justice may be served with a system that prevents any person or group of people from taking up parking spaces all day and excluding everyone else.
This is not to say however that any particular regime of parking regulations are necessarily mandated by the natural law. A man might park his car in a certain way pursuant to the regulations in one town and park in a different way according to the rules of another, without worrying that in changing his behavior he might somehow be doing something immoral. In contrast, a man may never murder, even if his city has made it legal to kill an innocent if one has fed the murder meter or commits one’s murders between the hours of 10pm and 6am on weekdays.
The reason for this difference is that parking regulations, though derived from the natural law (if just), do not emanate from it. As St. Thomas puts it, legal principles derived per modum conclusionis “are contained in human law not as emanating therefrom exclusively, but have some force from the natural law also.” In contrast, principles derived per modum determinationis “have no other force than that of human law.” The mere force of human law is still the force of law, and binds those subject to it, but it is a variable and contingent force.
St. Thomas’s exposition of the two modes by which human law is derived from the natural law is brief but powerful. When internalized, Thomas’s explanation of the relationship between the natural law and human law gives one a greater appreciation for both, and provides the conceptual tools necessary to properly assess laws and lawmakers.
Patrick Button