Here’s Hoppe’s succinct description of his own theory:
“Instead, it is a proof that it is impossible to propositionally justify non-libertarian principles without falling into contradictions.”(underline added)
The contradiction in Hoppe’s AE is not a formal or logical contradiction, but a “performative” contradiction, e.g., saying aloud “I am not talking.”
One simple problem occurs in Hoppe’s theory if he doesn’t account for the intention of the actor. So for example, someone who says aloud “I am not talking” may be practicing for a play, or wanting to hear the sound of his own voice, or trying to irritate a proponent of the AE, etc…
(this idea is taken from John Searle’s Minds, Brains and Science, p.57, which Hoppe cites in a debate with Block)
Another problem that is usually overlooked. Hoppe’s theory essentially links two things: “arguing for a nonlibertarian ethic,” and
“contradiction.”
The plain meaning of his theory is that anyone arguing for a nonlibertarian ethic contradicts himself, and such a contradiction is the negative consequence a person must suffer for advancing nonlibertarian ideas during argumentation. The contradiction is clearly meant to be something negative or harmful for the person committing it. If Hoppe’s theory were proven correct, then an actor could use the information Hoppe’s theory provides to avoid a specific type of harm or unhappiness: In order to avoid a type of uhappines (Y), do not argue for nonlibertarian ethics (X).
In other words, if Hoppe’s theory is correct, then it links two phenomena–the act of person A, and some negative cosequence to A–and shows person A how to avoid the consequence by abstaining from the act. But then, this is praxeology proper. It is a demonstration of the apodictically certain consequences of a specific form of human action, i.e., argumentation.
The main point is that if Hoppe’s theory were proven correct, it would constitute essentially an analysis of the necessary consequences of a specific means of action, and would thus constitute a simple praxeological insight or law.
The problem for Hoppe’s theory is that in order to demonstrate apodictically certain relations between things, the analytical method used may have to be free of particular content (in social science, this is referred to as “value free”) similar to the way mathematics and formal logic proceed, without specifiying particulars.
But this approach is closed to Hoppe to the extent he seeks to “justify” a particular: the Lockean private property ethic.
Hoppe is trying to establish apodictically certain relations while using particulars as theoretical elements. This is the source from which most of the problems derive.