Hans-Herman Hoppe

Per Wikipedia:

Hoppe says his theory proves that arguing for any political position other than libertarian anarchism is logically inconsistent. ... his theory is an a priori, value-free praxeological argument for deontological libertarian ethics.[1] Argumentation ethics asserts the non-aggression principle is a presupposition of every argument and so cannot be logically denied during an argument.

This is just the transcendental argument for God adapted for libertarianism, isn't it?

Seems like it. I think it works if we're only talking about two people. But what if those two people are debating whether to bomb the residents of the next country over? How does that in any way presuppose NAP?

Isn't the NAP kind of empty though? If I'm hitting you, I may not be "aggressing" against you.

Not necessarily. Though I think if it is consistently applied, it ends up undermining the ancap position. After all, property is theft.

Stephan Kinsella already wrote a rebuttal of that way of seeing the NAP, but GC demolished both. Speaking of that bald man, an article needs to be written on Kinsella, too. He's less of a crank in that he doesn't buy conspiracy theories, but he's HHH's lapdog and he's sort of a cultist.