We find the central, critical, controversial claim of Hoppe’s argumentation ethics where he writes, the fact of self-ownership is a praxeological precondition of argumentation (The Ethics and Economics of Private Property, page 412). In his original article on the topic, he expressed this idea as no one could propose anything or become convinced of any proposition by argumentative means if a person’s right to exclusive use of his physical body were not presupposed (EEPP page 400). I have always had difficulty understanding this part of Hoppe’s argument. How does he support this claim? The second quote mentions a right to use one’s body. No one can deny my ability to use my body. But the claim of a right to do so deserves a clear explanation. 
What does Hoppe need for his argument to work? Self-ownership must qualify as a universal norm that applies to everyone, everywhere, all the time, not just within the scope of a particular argument. Argument itself must depend on the self-ownership of participants. If those two assumptions hold, then everyone who argues implicitly asserts that the preconditions of argument are true, including self-ownership. 
Every action corresponds to a set of assertions, particularly an assertion “I am able to do this.” By standing up, I implicitly assert “I am able to stand up.” By arguing, I implicitly assert “I am able to argue, so all the necessary preconditions of argument hold true.” That idea makes Hoppe’s performative contradiction work. The question is, can Hoppe convince us that self-ownership is one of the necessary preconditions of argument? Hoppe must somehow connect my ability to move my body, a purely descriptive fact, with the normative claim that I have a right to do so, and show that without that right, I would never engage in argumentation.
Does universalizability give Hoppe the connection between the ability to move and the right of self-ownership that he needs? Universalizability declares that moral propositions must apply to all persons at all times. Such propositions may depend on circumstances if reasons can justify this without arbitrariness. But universalizability applies to propositions within the scope of morality, and we are discussing the practical preconditions of argument, which may or may not qualify as moral rules. Hoppe must show that argumentation presupposes robust moral rules, he can’t just assume this. If, in fact, Hoppe’s critics could prove that argument presupposes only facts and not norms, or if non-self-owners can argue, then the behavioral restrictions that persons must observe while arguing would have no moral content and would be exempt from universalizability. They would fit in the same category as the rules of games or the conventions of dances. Unless we first establish that argument presupposes a moral proposition, universalizability does us no good.
What is self-ownership? Hoppe defines self-ownership like so:Self-ownership simply means this: every individual owns (controls) his own physical human body and is entitled to use it and defend it. […] Every living human body is appropriated and controlled by a single independent (autonomous) conscious mind and will—a self or ego. [Hans-Hermann Hoppe In The Great Austrian Economists, edited by R.G. Holcombe, page 228]. But this is not much help, it leaves out something important. Self-ownership depends on self-control in two senses: I must be able to move my body and control it in that sense, but I also must restrain myself. Only if participants in argumentation respect each others’ boundaries may argumentation proceed. Persons tend to overlook this aspect of self-ownership. It is only as long as there is at least an implicit recognition of each individual’s property right in his or her own body that argumentation can take place [EEPP 317]. My right of self-ownership assumes the obligation of others to respect my property, and my obligation to respect theirs. Hoppe does not emphasize this interpersonal, cooperative aspect of self-ownership.
Maybe Hoppe could argue something like the following? Because I own myself, as part of what that means, I have a right to do that which is not morally prohibited or impossible. Because it is not impossible or morally prohibited, I have a right to argue. So the fact of my self-ownership enables argumentation.
When I do something, I implicitly assert that I have the ability to do it and have satisfied all the necessary preconditions. Must I assert the right to do it? Either I am asserting (implicitly) that what I do is not morally prohibited, or I assert that the category of moral prohibition does not apply. No neutral position offers itself, either one’s actions are justified or one denies the necessity of justification. If one denies justification, one permits others to treat one as an outsider, as a technical problem in Hoppe’s terms. (See Kinsella on dialogical estoppel.) If justification is unnecessary, everything is permitted.
Above we established that if I have self-ownership rights then I am entitled to engage in argumentation. Self-ownership therefore is a sufficient precondition of argumentation. But is it a necessary precondition? If self-ownership is merely sufficient, some non-self-owners may still engage in argumentation and Hoppe’s claim that argumentation presupposes self-ownership fails. In that case, some non-self-owner could deny self-ownership as a norm without self-contradiction. For Hoppe to succeed, only self-owners may ever argue.
Animals and criminals implicitly assert the right to violate our bodies and disrespect our right to our property. By this action they deny themselves the protection due to self-owners. In the case of animals, this makes sense, they do not violate Hoppe’s premise that only self-owners argue. But criminals can argue. Are they not self-owners? 
Block says they are not, and then gives a convoluted explanation of how they still cannot argue against self-ownership without self-contradiction. But this does not work, or at least, Hoppe must modify his premise for it to work. Hoppe’s premise, as stated, is unambiguous; only self-owners can argue. Only by insisting that prisoners are self-owners may Hoppe maintain his original premise. (He could also claim that when prisoners argue it is not really argumentation at all, but that is absurd.) Should we conclude that imprisonment of self-owners must be unjust?
When prisoners argue with each other, or argue in court, they embrace their self-ownership and assert it. When they commit crimes, they deny it. There is the contradiction, in the action of the criminal. According to Kinsella’s theory of dialogical estoppel, by committing a crime I assert that the rights and obligations of self-ownership do not apply to me, at least temporarily. We can interpret this as an agreement to opt out of the protections afforded by self-ownership. I may  choose imprisonment, or some other form of punishment, restitution, or atonement voluntarily and so reassert my self-ownership.
My sketch of Hoppe approaches the problem in two steps, going from the ability to control one’s body to self-ownership, then to the necessity of self-ownership for argumentation. Both moves emphasize the requirement that the participants in argumentation must embrace cooperative self-restraint. Hoppe’s critics think they see some problems in Hoppe’s argument. I will take a look at Hoppe’s argument from the perspective of the critics in my next post. If you see some problems in my sketch of Hoppe, either mistakes or useful additions, please comment.

Here is a link to my other posts about Hoppe’s argumentation ethics.