Matthew Yglesias is a little flip in his response to Tyler Cowen’s request “to see a progressive try to sum up an intelligent version of libertarianism here,” but I think Matt’s take is mostly right, if cynical.
I think libertarianism is best understood as a kind of esoteric doctrine. There’s strong evidence to believe that people who overestimate their own efficacy in life wind up doing better than those with more accurate perceptions. It follows that it’s strongly desirable for society to be organized so as to bolster myths of meritocracy. This will lead to individual instances of injustice and to a lot of apparently preventable suffering, but over the long-term the aggregate impact of growth (which, of course, compounds) on human welfare will swamp this as long as we can maintain the spirit of capitalism.
Anyway, if I may add my own two cents, what’s always struck me about libertarianism is how hopelessly impractical it is. Arguments from libertarians can typically be reduced to the idea that free markets and individual liberty will eventually lead to problems solving themselves (or as Matty says, “as long as we maintain the spirit of capitalism.”) As far as things go, I think that theory is in some respects right. If, in fact, carbon emissions are destroying the planet, eventually the damage will reach such a level as the market will demand we work to fix the problem (even massively wealthy owners of capital inputs don’t like forest fires, I guess). If, in fact, large profit incentives are not enough to impel pharmaceutical companies to work on problems other than me-too versions of penis pills, then eventually the market will demand pharmaceutical companies adjust their pipelines. Even if both cases proved the libertarian side of things, they would still be wildly impractical, wasteful, and borderline sociopathic ways to confronting the problems that we face.