Thanks to Ron Paul, I just had to explain to someone one of the reasons why libertarianism is stupid. So I'm sharing.
Libertarians will tell you that “behind every law is a man with a gun,” and I actually respect the hell out of the clear-eyed skepticism about violence which motivates this comment. But libertarians thus conclude that since violence is bad government is bad and we should eliminate it. Which is stupid.
I vigorously believe in the state's “monopoly on violence” ... provided the state in question is a liberal democracy.
The “liberal democracy” piece is key. That means not liberal in the sense of the liberal-conservative axis in American political discourse, I mean in the political science sense of Jefferson's “to secure these rights, governments are instituted among people, which hold their just powers by the consent of the governed”. A liberal democracy is a state constructed to protect the rights and liberties of its citizens and accountable to its citizens for its actions and institutions. Looking at our own government on those terms, it is easy to see that it is extraordinarily accountable and protective of individual rights if you compare it to most societies through the world and history, but is also well short of the ideal. I believe that it is possible to construct government institutions that deliver categorically better liberal democracy than we have now, and therefore it is more effective to work to build a better liberal democracy than to eliminate the state.
An accountable agent with a monopoly on violence is desirable for two reasons: some people are inclined to resort to violence, and some people are schmucks.
Because some people will resort to violence, you cannot eliminate the state. This is why those of us who dismiss libertarianism point to the Somalia example: in the absence of the state's public use of force, there is no check on personal use of force, which is a problem for all the familiar reasons.
Libertarians operate from the fantasy that we can wish that problem away. (And no, privately-employed security guards won't do the job as well as the state; the arguments why not should be familiar.)
Because some people are schmucks, you cannot eliminate the state. To have a functioning society, you have to make a million decisions about shared norms. Some of those norms are arbitrary: Either you drive on the left side of the street or the right. Some of them are about how you define property: Does someone own Harry Potter? Mickey Mouse? Sherlock Holmes? Hercules? Some of them are expressions of values: Do you allow advertisements to lie? How much pollution do you allow in a river?
Libertarians operate from the fantasy that it is most democratic to allow shared norms to emerge organically from a marketplace of individual actors. But in reality, schmucks can spoil the party by violating the norms that most people prefer: driving on the wrong side of the road to save a little time, publishing books they didn't write under their own byline, selling arsenic as penicillin, dumping toxic waste into that river. You need an agent of public will with the power to enforce norms, which requires the use of force.
It is right to find the use of force discomforting, but it is naïve to think we can wish it away. The solution is to make our agent of force institutionally limited and institutionally accountable to the populace: a liberal democratic government.