Since everyone has been skeeting on IOZ's anti-libertarian posts lately...

Oh yeah, you're so clever, IOZ -- too bad I ran up libertarianism's back and dunked cable guy-style like 2 years ago in this email to Bryan Caplan:

Dear Professor Caplan,

I was wondering if you could answer a few basic questions about libertarianism for me, as it has become quite voguish with many of my friends, and I can't seem to understand it at all.

As I understand it, libertarianism is a philosophy that extols free-markets and private property in the economic sphere and the Millian "Harm Principle" in the moral sphere. I don't think either of these basic premises is tenable.

As far as economics goes, it seems to me that libertarians fetishize markets. To me, markets are conditionally effective means to achieving the intrinsically morally significant end of welfare maximization. Government regulation is usually morally prohibited, not because it runs afoul of the faux moral principle that regulation is categorically bad, but rather because regulation tends to reduce efficiency and thus make everyone worse off.

Given this, what do libertarians say about market failures? Obviously libertarians realize that markets don't always maximize efficiency. Furthermore, I assume that libertarians support governmental intervention when it effectively corrects market failures.

But if you accept this, your principle is no longer "markets and economic freedom are good," but rather "economic efficiency (or wealth maximization, or whatever) is good," with the footnote that it happens to be true that markets and economic freedom (usually) promote wealth maximization (or whatever). Hence, it seems to me that libertarianism collapses into run of the mill (run of the mill? Is that a pun?) utilitarianism.

As far as morality goes, I feel the same way about the so-called "presumption of liberty." Usually it is the case that leaving people alone maximizes overall utility, but this is not always so. Consider, for example, the case of children. Presumably, no libertarian would argue that the state cannot act paternalistically towards children. But once you admit this, how can you deny that the state can act paternalistically towards adults who act like children? The relevance of childhood cannot be simply age, but rather the tendency to make certain types of shortsighted, counterproductive decisions. If the state can stop these decisions in the name of a person’s own good, regardless of his age, what left is there of the harm principle? Once again, it seems like libertarianism collapses into utilitarianism.

So, to summarize, why is libertarianism so popular when its appeal stems entirely from its frequent (yet empirically contingent) convergence with utilitarianism? It seems to me that libertarianism either a) is wrong, or b) equals utilitarianism.