Edwin Patterson, as quoted by Murray Rothbard, defines natural law as:
“Principles of human conduct that are discoverable by “reason” from the basic inclinations of human nature, and that are absolute, immutable and of universal validity for all times and places. This is the basic conception of scholastic natural law . . . and most natural law philosophers.”1
The word “principles” here might mean descriptive truths: for example that, “if you financially support your son into adulthood, then he will likely become lazy”; or that, “the best way to feed the world is through free markets.” This may be termed “positive natural law.” “Principles” could also mean moral principles:, whether it is simply wrong to let your son become lazy or to let people go hungry. Call this “normative natural law”.
Individuals, then, would use positive natural law to rationally choose the best means to an end. Normative natural law would be used to rationally choose the ends themselves.
Does normative natural law exist?
Few doubt the truth of there being such a thing as positive natural law. Skepticism of normative natural law, however, goes back to the cultural relativism of the Ancient Greek sophists. The skeptic who is supposed to have buried normative natural law is that king of skeptics, David Hume. According to Hume, reasoning from natural law can only be used to choose practical means, and that moral ends are only chosen via emotions.
“This is the second part of our argument; and if it can be made evident, we may conclude, that morality is not an object of reason. But can there be any difficulty in proving, that vice and virtue are not matters of fact, whose existence we can infer by reason? Take any action allow’d to be vicious: Wilful murder, for instance. Examine it in all lights, and see if you can find that matter of fact, or real existence, which you call vice. In which-ever way you take it, you find only certain passions, motives, volitions and thoughts. There is no other matter of fact in the case. The vice entirely escapes you, as long as you consider the object. You never can find it, till you turn your reflection into your own breast, and find a sentiment of disapprobation, which arises in you, towards this action. Here is a matter of fact; but `tis the object of feeling, not of reason. It lies in yourself, not in the object. So that when you pronounce any action or character to be vicious, you mean nothing, but that from the constitution of your nature you have a feeling or sentiment of blame from the contemplation of it.”2
As discussed and concurred with by Rothbard, A. Kenneth Hesselberg countered that Hume, in his own writings, inconsistently resorts to normative natural law. Hume states that man’s happiness depends on a social order. Hesselberg notes that the way a social order can be attained and preserved can only be found through contemplation of natural law. Therefore, according to Hume’s own theory, concludes Hesselberg and Rothbard, reasoning from natural law is needed for choosing ends.
While Rothbard is my intellectual hero, I must here differ with him. In Hume’s construction, the social order is a means to the end of human happiness. And, as Rothbard himself states, Hume recognizes the value of natural law in choosing means. And, nowhere in his construction, does Hume ever promote the use of natural law to choose the end of human happiness; it is only promoted for choosing the means of social order.
The establishment of moral axioms through reason alone also suffers from the problem of “progress ad infinitum“. A moral stance can be justified by another moral stance, which in turn is justified by yet another, and so on. Eventually there must be a principle of “unjustified justice” –a moral equivalent of Agrippa the Skeptic’s “unreasoned reason” and Aristotle’s “unmoved mover”–, and that can only be established by our emotions.
So I don’t subscribe to Rothbard’s “reason-only” conception of normative natural law. We can’t be said to rationally choose our moral ends. But neither am I convinced by Hume that there is no such thing as natural morality. I believe there are certain emotionally-based moral feelings which all men have in common, and which are hard-wired in our nature. These include, among others, promotion of our genetic posterity, individual self-interest, respect for property, and fellow feeling. Such natural morality can be termed “law” by virtue of their being universal and constant, if not for being discoverable by reason.
1Murray N. Rothbard, The Ethics of Liberty, Chapter 2: Natural Law as “Science”
2David Hume, Treatise of Human Nature, Book 3: Of Morals