Before going on to a look at why libertarianism is superior to Objectivist justifications for a minimal state, I want to briefly outline my history with objectivism. In the years 2000 and 2001, I was an objectivist of the ARI variety. I was very convinced that Rand's Objectivism was a viable, fully developed, closed system of philosophy. Gradually, I noticed what I thought were some serious flaws in some of Rand's argument - her ethical philosophy was insufficiently thin, her view of what constituted "reason" was too monolithic, etc. - and fell out of love with Objectivism.
Since then, the one sympathy I truly share with Rand is a belief in liberty, a minimal state, and the use of coercive force as suspect. That said, I think libertarian belief without Randian justification is much stronger than it is with.
First, one of Objectivists key complaints against non-Randian libertarianism is that "Although some call libertarianism a "philosophy," in fact it is just a relatively broad political position..." whereas Rand's defense of freedom "is a systematic philosophy: it starts with a theory of reality and a theory of knowledge, then develops a moral view using conclusions from the previous two fields, and all those conclusions provide the basis for its politics. (1)
Guilty as charged! There is a plurality of possible justifications for libertarianism: thinkers have argued that libertarianism is justified on utilitarian grounds, via natural rights, on religious grounds, or in a plurality of other ways. If libertarianism is to leave people free, though, I could not see that a "one justification system fits all," (like Rand's) as fitting a libertarian community.
In fact, if one suggests that there is only one very specific way to justify liberty (as Rand does) then you run a serious risk of restricting yourself into a minority view. As Rand views hers as a deductive system (it is actually inductive, but that is no matter), then she is saying, "If you don't share my views on epistemology or metaphysics, you can not possibly be a true defender of liberty. Check your premises!" With this very restrictive view, you will win only a handful of adherents (as witnessed by the relatively small number of people who actually consider themselves objectivists).
I have long been an advocate of having a plurality of justifications for any moral or political action. The more ways you can justify x (x is justified on utilitarian, natural rights, pragmatic, grounds) then the more chance you have of being able to justify x to a wide variety of audiences. As I take it a free society will likely have a variety of moral codes for people to subscribe to, it seems obvious that the more traditions one can appeal to in justification of a moral act, the better one will be. Rand's "one size fits all" practice of making a proper defense of liberty contingent on literal adherence to a very particular philosophic code means that you are dooming yourself to appealing to the few, rather than to the many.
More troubling still, whenever I read Rand (or an Objectivist's) denunciation of libertarianism, I can't help but think that they are not defending freedom so much as "freedom to be an Objectivist." In other words, Objectivists' insistence that "rational" people will agree on just about everything (i.e., they will follow Rand to the letter) reminds me of the type of "free society" that exists in Mormon Utan, where everyone is free to act as they choose (with the understanding that if one makes a wrong move, one will be excommunicated or cackled into submission.)
Take the following invective from Peter Schwartz:
"Subjectivism, amoralism and anarchism are not merely present in certain “wings” of the Libertarian movement; they are integral to it. In the absence of any intellectual framework, the zealous advocacy of “liberty” can represent only the mindless quest to eliminate all restraints on human behavior—political, moral, metaphysical." (2)
First, this is a bad oversimplification. No libertarian that I have ever been in contact with has ever advocated an "eliminat[tion of] all restraints on human behavior." Libertarians certainly draw the line at the Millian (yes, it was around before Rand) "no harm" principle - the principle that, while certain acts are permissible, government is justified in "stepping in" as soon as one person or ground engages in coercive harm to another. In other words, libertarians are far from the hedonists Schwartz describes, but agree fully with Rand (and Locke) that the purpose of government is to protect the individual.
To libertarians, it seems obvious that no free society would endorse one moral system - particularly a horribly restrictive one - as Schwartz seems to want for his "free society" (Galt's gulch, perhaps, where everyone is completely like-minded?). To libertarians, it is obvious that when you leave people RELATIVELY free to live their own lives, a plurality of value systems and ways of life will emerge; people don't think the same, and generally, a society of people that thinks the same is indicative of coercion.) If Galt's gulch or an Objectivist village is teh model of a free society, then it is either indicative that coercion or threat is involved, or is a "membership only" society that restricts membership to those subscribing to a certain view. Neither is consistent with any real libertarianism.
Would an Randian "free society" look like the Ayn Rand Society, where those championing liberty exercise banishment from their group at fast rates? (The David Kelley incident is instructive here, as it led to several 'banishments' from the club, holding no idea of academic freedom. Another great example of such childish and collectivistic behavior can be seen here.)
Objectivists like Schwartz and Peikoff hold an interesting admixture of zeal for individual rights but absolute scorn for those who would exercise it in any way of which they disapprove. Of course, intolerant individuals can certainly function within a free society, and a free society is one in which they would not be barred or coerced unless they did real harm to others. But I shudder to think of how quickly a free society consisting only of those individuals would erect into a statist one where the state monitors behavior to ensure that it is compatible with "reason." Or such a society of like-minded intolerant individuals may quickly become "free" in the way Mormons are in Utah: individuals are free to act in accord with the restrictive ethical code that binds them under threat of banishment or ostricization.
What really concerns me, though, is Objectivism's negativity towrads objectivism's inability to provide strong moral sanction:
Anyone from a gay-rights activist to a criminal counterfeiter to an overt anarchist can declare that he is merely asserting his “liberty” (3)
Why is Schwartz concerned that libertarianism cannot stop the "gay-rights activist" or "overt anarchist" from exercising his liberties? (Surely, libertarians are justified in penalizing the criminal, via the "no harm" principle). My fear is that, in Schwartz's "free society," the gay-rights activist would be censored or censured for doing nothing other than adcovating for the rights of gays to have relationships and marry. (Rand is incapable of justifying, on Objectivist principles, why gays should not be able to marry.) Schwartz also seems desirous of being able to stop "overt anarchists" from expressing their obviously non-Objectivist views.
Schwartz really does seem to want a society where all views other than Objectivism meet with strong reprobation. This is not defense of freedom, but defense of freedom to follow a restrictive code or be censured (a Mormon-esque freedom with Uncle Warren's role being replaced by Aunt Ayn).
This is why I think libertarianism of a plural variety (and with plural justificaitons) leads to a safer liberty than Rand's very restrictive Objectivist view of freedom. It is more inclusive by allowing for a plurality of justifications (appealing to a wider and more diverse audience), and it is certainly more free in that it would allow various groups with various beliefs and codes to live with the maximum freedom possible (as consistent with a "no harm" or similar principle.
(For anyone curious, the libertarianism that I am in favor of looks much like that written about in the works of William Galston, particularly the book Liberal Pluralism..)