Part I here.

Consider the following hypothetical that takes place under a libertarian (Nozickian/Randian/Rothbardian) state.  A rich person has a pile of money in her house.  A poor person, wanting some money, goes into the house and starts taking it.  When the rich person tells the poor person to stop, the poor person refuses.  The rich person may now call in the force of the state to stop the poor person from taking the money.  The state may, using physical force if necessary, imprison the poor person and take back whatever money the poor person took from the rich person.

Non-aggresion principle endorsing libertarians would say that the state’s forcible protection of the rich person’s money is legitimate.  But for something that is allowed under the non-aggression principle, it sure seems pretty aggressive to me!  What’s going on here?

The two cases (the one from part I and the one above) aren’t the same, the defensive libertarian might claim.  In the first case, the state is coercively seizing property that belongs to the rich person, whereas in the second case, the state is simply protecting the rich person’s property from a would-be thief.

However, this response doesn’t hold up, because it presupposes the institution of property rights, which are a social institution with certain rules about what it means to own something.  Among them are rules about when it is permissible to use physical force against another person.  It’s an assumption about the existence of property rights, not the non-aggression principle, that’s doing the work here.

State-backed redistribution and state-backed property rights are both, in a sense, coercive.  The question obviously becomes, which sort of coercion is justified?  The non-aggression principle, as I have shown, is unable to provide the answer, and it therefore does not necessarily entail libertarianism.