I was stirred to think about our current state of affairs by a scholarly article by R. Scott Clark of Westminster Theological Seminary, Escondido California. Its title is "Calvin on the Lex Naturalis" (Stulos Theological Journal, 6/1-2 (May-November 1998) 1-22).
Dr. Clark's main point is that Calvin defined natural law by identifying it with the Ten Commandments or moral law of God. This is very similar to the view held by Blackstone (he called it the "laws of Nature"— a phrase found in our Declaration of Independence).
In contrast, Thomas Aquinas viewed natural law as what the mind of man can discern by reason. His presupposition was that man, because he contains the image of God, has an "inclination to the good". Id. p. 4. Of course, Calvin, with his understanding of total depravity, did not think this was a viable basis for a moral system.
Although the Calvin-Blackstone view (that is, we look to God's revealed law in scripture for reference) was reflected in the early English Common Law, the Thomistic view seemed to take over in our country almost from the start. Certainly, by the time of the ratification of the Constitution, it was ascendant. Read a few opinions by the early Supreme Court Justices for evidence.
People who study jurisprudence speak of natural law theory being the main theory of jurisprudence in the 18th and early 19th centuries. It began to be eclipsed by the Legal Realism, which bloomed into Positivism by the early 20th century.
Positivism is considered a reaction to natural law theory. It holds to the idea that law is "manufactured" by social convention. The phrase "widely and warmly shared values" is something of a touchstone for it. The idea is that judges, and legislatures, dictate what the law should be according to community norms. Instead of the law being just because it is right, the law is right because it is the law.
But it struck me that Thomas and the Positivists are really saying the same thing. Following Thomas, law is discovered by using man's reason. What should be right is what is reasonable. But depraved men are by definition and in fact unreasonable. Using their faulty reason, they come up faulty standards. When these don't work, they seek what the majority of men think is reasonable and make that the law. The end result under either the Thomist version of natural law or legal positivism is the same: the moral standard is discovered by the latest opinion poll.
In the jurisprudence world, the natural law people are considered to be dinosaurs. The positivists are the current conservatives because they still want law based upon social tradition. Critical Studies people, FemCrits, or whatever is their postmodern term du jour, push the envelope a bit further: the law is whatever the judge says it is based upon, among other things, what she* had for breakfast and whatever convention suits the moment.
These days, law is process, not justice. There is essentially no standard, just inertia. Conservatives and liberals can fight all they want about the terminology, but they miss the primary point: their presumptions are all grounded in rebellion against God.
Thomas Aquinas owed his thinking to the philosopher Aristotle, that granddaddy of empiricists. Calvin's view of philosophers, quoted by Dr. Clark, is appropriately dismissive:
. . . they saw things in such a way that their seeing did not direct them to the truth, much less enable them to attain it! They are like a traveler passing through a field at night who in a momentary lightning flash sees far and wide, but the sight vanishes so swiftly that he is plunged again into the darkness of night before he can take even a step – let alone be directed on his way by its help.Id., p. 8, (quoting Calvin's Institutes, 2.2.18).
Of course, Paul addressed this too:
Beware lest any man spoil you through philosophy and vain deceit, after the tradition of men, after the rudiments of the world, and not after Christ. Colossians 2:8.
*(Feminine Critical Legal Studies convention requires the generic personal pronoun to default to "she" or "her", etc.)