States, guns, and legitimacy

See Kevin D. Williamson, Exchequer vs. Economist, on the distinguishing feature of states as social institutions:

Socialist or otherwise, all states finally rest on force: You decline to participate in whatever is the Netherlands’ version of serving the community through the instrument of the state long enough, they send a guy to your house with a gun to seize your stuff or haul you off to jail; resist and there will be violence. That’s what states do, and it is not necessarily illegitimate.

The resort to violence is what makes the question of what kind of things it is legitimate for states to do an important moral concern. It seems to me perfectly reasonable to shove a gun in somebody’s face to stop him murdering, raping, or robbing. It seems to me entirely unreasonable to shove a gun in somebody’s face to extort from him money to fund a project to get monkeys high on cocaine. Those seem to me fairly reasonable distinctions. It is illegitimate for government to use force or the threat of force for projects that are not inherently public in character.

By itself, of course, this last isn't that good a criterion for state legitimacy, since people will always try to argue that their pet project is indeed "inherently public in character". But Williamson sharpens the criterion a little later:

... I would like to make it clear that I am not indulging in a figure of speech: I think it’s a pretty useful heuristic: If you’re not willing to have somebody hauled off at gunpoint over the project, then it’s probably not a legitimate concern of the state.

Which is at least an interesting rule of thumb, particularly as a reminder of the violence that lies at the basis of the state as such.