John, in comments of the previous post, write:
... skepticism is really a bedrock principle of serious libertarian scholarship. A good suggestion would be to get out of the sandbox and read Richard Epstein's "Skepticism and Freedom."
The positivist, pragmatist, consequentialist, law and economics libertarians such as Posner, Epstein, the Friedmans, etc. have a good, flexible model of economics of legal issues. But the problem is the empirical content needed to make decisions (see Epstein quote below.) As soon as you claim to know the empirical content needed, you can be doubted on Hayekian grounds. Those guys substitute their personal authority for the kind of detailed and dispersed information that Hayek attributes to the market. They might as well be setting prices based on their personal authority. Legislative solutions might not be as good as markets, but they probably aggregate information better than these individual authorities.
What I really liked in Epstein's "Skepticism and Freedom" was this bit:
When you are young in this world, you believe that the class of deductive truths about social matters is larger than it turns out to be. The great attraction of libertarian thought lay in its deductive power. The hope was that you could axiomatize the system and sort of render social problems amenable to a set of principles that yielded necessary or deductive truths. That vision certainly fired my early academic life... Essentially, as I have gotten older and maybe a little bit wiser -- which why that 30 years really start to matter -- I have discovered, to my infinite regret, that most of the serious debates over the basic principles of any political order have an irreducible empirical content.
In that one short paragraph, he invalidates most libertarian writings, including quite a lot of his own.