Debates between libertarians and those who advocate any kind of statist intervention frequently take the form of “X should happen vs. X should not happen”. For example a budding libertarian might argue “the post office should be privatised!” whereas his opponent may cry “the post office should be state owned!”
Lost in these kinds of exchanges is the fact that libertarianism is a norm concerning the application of violence and nothing more (and, ultimately, all political philosophies are theories concerning which rights to property may be enforced by violence). Libertarians do not, therefore, necessarily stand against any kind of social or economic organisation per se; even socialised or communal property is perfectly fine so long as all of the participants in the commune have contributed their shares voluntarily, and have agreed to abide by its rules of distribution. Rather, our strenuous objection is to the use of use of violence to enforce these forms of social organisation upon unwilling participants.
There is, of course, much that the state does which is irrevocably violent and, thus, indefensible to libertarians, whether its offensive wars, assassinations, spying on the citizenry, and so on. Indeed, most of these things are simply indefinable without reference to their violent nature, and so whoever perpetrates them on whichever terms would be breaching the libertarian ethic.1 But there is a whole lot else that the state does which is not necessarily violent, and could be carried out peacefully or voluntarily: healthcare, policing, roads, and so on. Carrying out these functions becomes violent only through a) the fact that people are forced to pay for them through their taxes, and b) competing services can be forcibly prevented from (or otherwise hindered in) operating.