One of the things about libertarianism that really appeals (at least to us conservatives) is the emphasis on freedom of thought and the rule of rationality in human affairs. Personally I've always been of two minds about this, however (one of the great benefits of personal intellectual freedom, I suppose, is that you can literally think whatever you want, even two different things at the same time). On the one hand, it is difficult to imagine anything more important than the dignity of the human person as manifested in the freedom to believe whatever one wants. On the other hand, it seems obvious that some beliefs are better than others--better in the sense of being more rational. Ordinarily I can see no reason to prevent folks from believing irrational things, but of course some folks with irrational beliefs have had deleterious effects on the rest of us, and that doesn't seem right.
We could invoke the harm principle: you may act on your beliefs only to the extent that your beliefs do not have deleterious effects on others. This is the line taken by many libertarians. But this is an instance of constraint, not freedom. What if I don't happen to share your belief in the harm principle? What if I get my kicks from harming others? Who are you that you get to restrain me from doing so? Why do you have the right to impose your beliefs on me? This is a tough one, at least for the libertarian. Some just blow it off, asserting that it is a straw man, that no one really holds such sociopathic attitudes, other than crazy people, and society does not, in fact, have any obligation to honor the beliefs and attitudes of crazy people. That's not much of an argument, of course, and serious libertarians don't make it; instead they look for rational grounds for constraint that don't put too great a burden on personal liberty. There is a further difficulty, however: it is impossible to establish any such grounds without invoking purely arbitrary preferences, and that approach, while it may settle the issue of the harm principle, is not an appeal to pure rationality as such.
What some folks think the role of "pure rationality as such" in moral reasoning amounts to can, on occasion, be fairly amusing. There was a very funny piece in Best of the Web Today for 30 May about an essay by libertarian Tim Kern that argues that the time wasted by the TSA in conducting searches at airports is the moral equivalent of killing 2582 people each year ("killing" here meaning time wasted standing in line). I have a good friend, also a libertarian and a specialist in moral theory, who maintains that whoever it was who was ultimately responsible for mandating the installation of seatbelts on airlines is morally responsible for the deaths of every single person who has chosen, for economic reasons, to drive rather than fly. His argument is that the mandate for seatbelts in airlines cost money that was passed on to the consumer, and some folks may prefer to drive than to pay the higher cost of flying. But the use of seatbelts in airlines is largely a waste of time, since you're dead if the plane crashes whether or not you're strapped in. And since flying is statistically much safer than driving...well, you do the math.
We all have our little foibles, of course, and it is silly to point to one or two such examples with the purpose of establishing the outlandishness of libertarian approaches to moral problems, since for every such nutty libertarian analysis there is probably an equally wacky liberal or conservative analysis, either of the same problem or of a different one. What is a little harder to explain, in my view, is the libertarian love affair with Ayn Rand. I know many smart, thoughtful libertarian philosophers, and it never ceases to amaze me how many of them consider themselves objectivists. I suppose that what attracts them are the emphasis on reason and the autonomy of the individual, but these principles are available in a wide variety of theoretical frameworks, and it remains a mystery to my why anyone would find the packaging of the Ayn Rand Institute, for example, more attractive than any of these other frameworks. To call objectivism simplistic and banal would be to give it more credit than it deserves (to see what I mean, just have a look at the video and audio samples of Rand's own words on the Institute web page--or read Atlas Shrugged or The Fountainhead [if you can sit through it]).
When I was growing up in the 1960s my mother was a huge fan of objectivism--she subscribed to the little journal, The Objectivist, which Rand herself published from 1966 until 1971. My mother would leave these things lying around the house, and I would often give them a look. I remember that there was always something by Rand, Peikoff, or Weiss in just about every issue--it was not an academic journal, publishing peer-reviewed articles, but more along the lines of a New Republic or National Review. I don't think I read anything with any care until I was beginning to get interested in politics in the early 70s. I remember that there was a piece, in the summer I started the 8th grade, called "The Age of Envy" or something like that, in which Rand drew a distinction between envy and hatred, arguing that the former is a natural and, indeed, humane emotion while that latter is fully inhuman. I remember agreeing with the essay at the time; I was probably just the right age for it.
De gustibus non disputandum est, as they say. Reason is not a bad thing to be constrained by, that's for sure. But one does wonder what the nature of the common good is on this construal, if it is even anything at all. Maybe moral realism is not fully compatible with this line of thought. That would be ironic, in a way, since this line of thought appears to be opposed to moral relativism.
But hey, that's the beauty of freethinking!