Why justify the NAP? Let me ask you and everyone else something: did you have to be convinced of the NAP by argument, or did it strike you as eminently agreeable as soon as you understood what it actually meant? Did it take an intellectual argument to convince you, or just simple clarity? I don’t see that the major obstacle is to justify the NAP, but rather to alert people to such ideas or to even more effective ones as a way of showing them how the State conflicts with values they already hold.
And natural rights arguments are going to work on such people?
Who wants unemployment? And I thought you weren’t a minarchist - without a State who’s going to “implement” minimum wage on everyone else?
The nihilist wouldn’t need Mises’s theory to figure that out. What the nihilist could learn, however, is that certain other “non-libertarian” actions that he otherwise would have performed are not in his interests. Objective ethical prescriptions won’t help with that, as there are no necessary consequences for not following them.
Who exactly needs to have a principled commitment to the NAP for a libertarian society to work? Surely not…legislators!?
This is fine wordcraft. Notice the conspicuous word choice: “Justice” instead of “(objective) ethics,” although that was clearly what he meant. Substitute it back in and see how it sounds:
“Ethics, not the weak reed of mere utility, must be the motivating force if liberty is to be attained.”
It becomes nothing more than a bald assertion.