Somalia is, or at least was, a land without a government. If libertarians or randians are correct, it should be a land flowing with milk and honey. Of course, this is not the case. At least, that is how the argument goes.
I'm a former libertarian of the anarcho-capatilist-rand flavor, and I think there are much better arguments against that stance than somalia.
Libertarianism is not anarchism, nor does it ever purport to be. In fact, libertarianism holds that a government should be in place, and that its job is to protect the rights (defined by libertarianism--most often, the Bill of Rights is pointed to) of its citizens.
Libertarians do overlap quite a bit with anarcho-capatilism and randism. You might not define libertarianism that way, but many do. The best you might say is something like, 'libertarianism, as espoused by [X], hold that a government should be in place.' As a counter example, I can easily find self-identified libertarians who are anarchists.
Somalia was a land without a government for a very brief period. It now (and has, for many years) has several governments in different regions. Some are based on Sharia (or at least purport to be), others on Guurti (traditional clan-based government). None are or claim to be based on libertarian principles.
None of it's governments are recognized by the UN, but as far as I'm aware, no one claims that the mere withdrawal of UN recognition of a government leads to prosperity.
>None are or claim to be based on libertarian principles.
I think part of the argument is that if libertarianism is so good / efficient / other desirable criteria, why don't societies naturally evolve into those societies?
Again, I don't think that this is the entire argument, or even a particular good one (in the case of somalia). I'm just pointing it out.
I'm a former libertarian of the anarcho-capatilist-rand flavor, and I think there are much better arguments against that stance than somalia.