I'm not a capital "L" Libertarian. For one, those folks are a bit too isolationist for my taste. For another I've read some capital L Libertarians who are in favor of legalizing all drugs, without exception.
But on a lot of issues they are close enough to what I believe and Arnold Kling's post offers a good rationale, especially this:
I believe that even if government officials were free of special-interest influence and wanted to be pro-social, they would fail. They under-estimate their own ignorance, and in choosing leaders the political process selects for a lack of humility. Officials are prone to blunders, and the error-correction mechanisms are much weaker in the public sector than in the private sector. Markets tend to correct their failures. Governments tend not to.