Most people are comfortable thinking about libertarianism in connection with the idea of natural rights. And Rothbard’s form of libertarianism is, indeed, a natural rights position. But it is also a position based on a kind of natural law ethic, and this position is one that is less familiar to most libertarians. The first five chapters of The Ethics of Liberty are devoted to articulating and defending the natural law foundation of Rothbard’s libertarian view. This post will summarize and assess them. The first post in this series covered the introduction by Hans-Hermann Hoppe.

Chapter One, “Natural Law and Reason,” opens with a defense of the concept of human nature, a concept that Rothbard saw as being unfairly dismissed by intellectuals at the time. Rothbard rejects the claim that appeals to human nature are necessarily religious in nature, and seeks to defend the concept as the cornerstone of a secular natural law theory. The defense itself is reasonably straightforward, and is developed in greater detail in chapter 2, “Natural Law as ‘Science.'”

To say that human beings have a nature is to say that there is something that man is like (9). It is to say that there are certain regularities that we can discover about him – he dies if he doesn’t eat, he has a finite understanding of the world, and so on. Certain causes produce certain effects, and reason allows us to discover the connections between the two.

The observable behavior of each of these entities is the law of their natures, and this law includes what happens as a result of the interactions. The complex that we build up of these laws may be termed the structure of natural law. (10)

So far, so good, and one wonders why anyone would be opposed to the ideas of human nature or of natural law if this is all they amount to. But, of course, Rothbard doesn’t want to end up with a mere catalogue of empirical regularities about human beings. He wants not just a set of natural laws, but a natural law ethics. And ethics is not just about what man is like, but what he ought to be like. And that’s the rub. Because now Rothbard seems to run right smack into David Hume’s famous “is-ought problem.” Most readers of this blog, I suspect, have heard of this argument. But for those of you who’ve never read it in its original, it’s worth doing. It is surely one of the most influential arguments in moral philosophy in the past 250 years, and Hume’s presentation of it is surprisingly succinct. Here’s the whole thing, tacked on almost as a footnote to an argument that our moral distinctions are not derived from reason in his Treatise of Human Nature:

I cannot forbear adding to these reasonings an observation, which may, perhaps, be found of some importance. In every system of morality, which I have hitherto met with, I have always remark’d, that the author proceeds for some time in the ordinary way of reasoning, and establishes the being of a God, or makes observations concerning human affairs; when of a sudden I am surpriz’d to find, that instead of the usual copulations of propositions, is, and is not, I meet with no proposition that is not connected with an ought, or an ought not. This change is imperceptible; but is, however, of the last consequence. For as this ought, or ought not, expresses some new relation or affirmation, ’tis necessary that it shou’d be observ’d and explain’d; and at the same time that a reason should be given, for what seems altogether inconceivable, how this new relation can be a deduction from others, which are entirely different from it. But as authors do not commonly use this precaution, I shall presume to recommend it to the readers; and am persuaded, that this small attention wou’d subvert all the vulgar systems of morality, and let us see, that the distinction of vice and virtue is not founded merely on the relations of objects, nor is perceiv’d by reason.

To simplify Hume’s point somewhat, suppose we employ our reason to discover that as an empirical law of nature:

1) Human beings die when you cut their heads off.

Does reason allow us to conclude from this that

C) We ought not cut people’s heads off?

Strictly speaking, no. Logically, we could only draw that conclusion if we had an additional premise:

2) We ought not cause human beings to die.

But reason didn’t tell us that. Reason told us what effect (death) a certain cause (cutting off a head) produces. It told us, in other words, about a certain empirical regularity in the natural world. It didn’t tell us that the effect is one that we ought not produce. That claim is a normative claim, not an empirical one. So what the “is-ought” argument purports to show is that we can’t derive a conclusion about what we ought to do unless we already start with a premise about what we ought to do. We can’t “bootstrap” our way up from purely empirical generalizations to a normative conclusion. But this is exactly what Rothbard’s argument seems to try to do. Consider the following representative claim:

The natural law ethic decrees that for all living things, “goodness” is the fulfillment of what is best for that type of creature; “goodness” is therefore relative to the nature of the creature concerned…In the case of man, the natural-law ethic states that goodness or badness can be determined by what fulfills or thwarts what is best for man’s nature.” (11)

Arguments of this sort start with some premises about what man is like (say, “a rational animal”), and then go on to draw some conclusions about how man ought to behave (“rationally!”). But not only does this not follow, as Hume’s argument shows, it also just seems plain wrong. Suppose, to take an argument popular among natural law Catholics, that heterosexual sex is “natural” and homosexual sex is not. Why isn’t the correct response to this, “So what?” If homosexual sex can provide the same kinds of good that non-procreative heterosexual sex can (physical pleasure, emotional closeness, etc.), then why should we care whether it’s “natural” or not? Similarly, if Aristotle was right and being a philosopher turns out to be the most perfect realization of human nature, why should this matter to us if being a philosopher causes us to be miserable, poor, lonely individuals? i.e. if it undermines the values that we actually care about? Why should the fact that something is natural entail that it is something we ought to do or value?

Rothbard is aware of this sort of objection, of course. And it’s not as though the argument he’s making lacks a respectable pedigree. He is, as he notes, following broadly in the Aristotelean / Thomistic tradition. And there are sophisticated arguments out there by smart people in defense of that tradition – including some by our own Rod Long. But Rothbard doesn’t make those sophisticated arguments, and his brief responses to the arguments I suggest here strike me as utterly unpersuasive. (See my comment below for a discussion of one such response)

The fact is, most of us today, and perhaps especially those of us who are attracted to political libertarians, are subjectivists about a broad range of moral values. Not all of it, of course. Most of us think that things like stealing and torturing are objectively wrong. But when it comes to who we have sex with or in what way, what religion we practice (if any), how we spend our free time, most of us think that there isn’t any universal morally correct standard of behavior. What’s right for you depends very largely on what you like, and might be quite different from what I like. For many of us in the liberal / libertarian camp, this subjectivity about values is part of the reason we’re attracted to freedom. Freedom is good, in part, because it lets different people live their lives in the way that’s good for them, and doesn’t try to impose a single standard of value on everyone.

My point here isn’t to make any kind of knock-down argument against natural law ethics. You could, I’m sure, tweak a natural law ethic to account for the kinds of subjectivity we find attractive nowadays. And you could (and some have) come up with an argument for libertarianism that builds on a natural law ethic. So, I’m not saying that the tension in Rothbard’s work isn’t resolvable. Just that it needs resolving, in a way that many of Rothbard’s libertarian fans might not even be aware of. A lot of people probably assume that the subjectivism of Rothbard’s Austrian economics runs all the way down through his ethical theory. That, as we’ve seen, is a mistake. Rothbard believed the robust objectivism of his natural law ethic to be compatible with a subjectivist theory of economic value, and a political philosophy that accords individuals the freedom to pursue their (possibly incorrect) subjective moral values. Whether he was correct to believe in this compatibility is a different and far more difficult question.

Chapters 3 and 4 continue the discussion of natural law theory, but make far fewer claims that strike me as philosophically controversial. Chapter 3, just a little over 3 pages in length, makes the point that natural law theories provide a moral foundation from which to launch a radical critique of existing, positive law. This is true enough, though not, as far as I can tell, distinctive of natural law ethics as contrasted with other objectivist moral theories. A Kantian or utilitarian foundation could provide and has provided a similar foundation for radical politics.

Chapter 4 briefly discusses the connection between natural law and natural rights. This chapter draws heavily on Locke, an exhibits one of the most annoying characteristics of Rothbard as a historian of thought – his tendency to ascribe the label of “libertarian” in an entirely anachronistic way to anyone who expresses views that a contemporary libertarian might agree with. I’ve argued elsewhere on this blog that it’s a mistake to think of John Locke as a libertarian. Readers of Rothbard’s Austrian Perspective on the History of Economic Thought will find plenty of other examples. Rothbard just doesn’t seem to get that while of course libertarians oppose slavery, and support private property, that doesn’t mean that everyone who opposes slavery and supports private property is a libertarian.

So that’s it for Part I of the book. Up next is Part II, “A Theory of Liberty,” with lots of meaty and exciting chapters on self-defense, land monopoly, the rights of children (with a famous footnote to a young Hillary Rodham!), and more. I hope you can read along and join the conversation! I’m pleased to see that Jason Kuznicki at Cato has joined the reading group. It looks like he has a more sympathetic assessment of Hoppe, and I suspect the same is true of his view of Rothbard. I’m looking forward to reading his continued reflections, and encourage others to join the fun!  Bryan Caplan? It’d be a nice followup to your reading group on For a New Liberty!  Anybody at the Murray Rothbard Ludwig von Mises Institute?  I’m a slow reader, so it’s easy to keep up with me!