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Argumentation ethics is a proposed proof of the libertarian principle of self-ownership developed in 1988 by Hans-Hermann Hoppe, a Professor Emeritus with the University of Nevada, Las Vegas College of Business and Ludwig von Mises Institute Senior Fellow. Responses have mainly come from Hoppe's colleagues at the Mises Institute, among whom the argument's reception has been mixed.
Argumentation ethics aims to prove that arguing against self-ownership is logically incoherent. Hoppe states that if argumentation praxeologically presupposes the norm that both the speaker and the listener are allowed to exercise exclusive control over their respective physical bodies in order to settle a disagreement or resolve a conflict over scarce resources, then it follows that propositions propounded during such argumentation cannot contradict this norm without falling into a (dialectical) performative contradiction between one's actions and words. Thus Hoppe concludes that despite aggressive behaviour being possible, it can not be argumentatively justified.
Hoppe states that his theory is an a priori, value-free praxeological argument for libertarian ethics. Argumentation ethics asserts the non-aggression principle is a presupposition of every argument and so cannot be logically denied during an argument. Argumentation ethics draws on ideas from Jürgen Habermas's and Karl-Otto Apel's discourse ethics, from Misesian praxeology and from the political philosophy of Murray Rothbard.
Hoppe first notes that when two parties are in conflict with one another they can, eventually, choose to resolve the conflict by one of two means. Engaging in violence, or engaging in honest argumentation. In the event that they choose argumentation, Hoppe asserts that the parties must have implicitly rejected violence as a way to resolve their conflict. That is, both participants agree that each one has to exercise exclusive control over their body parts in order to produce and perceive meaningful sentences. He therefore concludes that non-violence is one of the underlying norms (Grundnorm) of meaningful argumentation that is accepted by both participants.
Hoppe states that since both parties act to propound propositions in the course of such argumentation, and because argumentation must presuppose certain norms (that he specifies, non-violence among them), then the content of the propositions cannot negate the presupposed propositions of argumentation. To do so is a performative contradiction between one's actions and one's words.
Deriving the non-aggression principle from the presuppositions of argumentation
Argumentation ethics aims to show the non-aggression principle (in a certain formulation) follows from the presuppositions of argumentation, and so it cannot be denied.
Other than dismissing propositions calling for violence as means to resolve conflict, Hoppe also argues that only universal norms are consistent with such meaningful argumentation, as, he claims, arbitrary categorical distinctions have no intersubjective justification, which also must be a presupposition of such argumentation. Hoppe then also argues that since argumentation requires the active use of one's body, all universal norms for resolving conflicts over the human body aside from self-ownership are inconsistent with argumentation, as they would not allow one to independently move. Hoppe then argues that since the resolution of conflicts over external resources must also be objectively justifiable, only the physical establishment of an objective link by original appropriation (i.e., homesteading) is a norm compatible with such a requirement. From these Hoppe concludes that only the non-aggression principle of self-ownership and Lockean homesteading can be justified in an argument without contradiction.
Punishment and self-defense
Bearing reference to the legal doctrine of estoppel, Stephan Kinsella's "Dialogical Estoppel" theory extends argumentation ethics by considering an argument between a victim and aggressor. Kinsella argues that an aggressor cannot consistently object to being proportionally punished for his act of aggression, by the victim or by the victim's representatives, because by committing aggression he commits himself to the proposition that the use of force is legitimate, and therefore, his withholding consent based on a normative right not to be physically harmed contradicts his aggressive legitimation of force, i.e. he is "estopped" from withholding consent.
Responses from scholars
Various responses to Hoppe's argument came from Mises Institute scholars. Some of them accepted his argument, among them attorney Kinsella and economists Walter Block and Murray Rothbard, who called it "a dazzling breakthrough for political philosophy in general and for libertarianism in particular," adding "he has managed to transcend the famous is/ought, fact/value dichotomy that has plagued philosophy since the days of the Scholastics..."
Mises Institute economists Bob Murphy and Gene Callahan rejected Hoppe's argument. The late Austrian Economist David Osterfeld, an adjunct scholar at the Mises Institute, also rejected Hoppe's argument in an essay to which Hoppe subsequently responded. Walter Block has since defended the argument and Marian Eabrasu rebuts a wide range of criticisms.
Ludwig Von Mises Institute Senior Fellow and Auburn University philosopher Roderick Long reconstructed the argument in deductively valid form, specifying four premises on whose truth the argument's soundness depends. Long goes on to argue that each premise is either uncertain, doubtful, or clearly false. He summarizes his views by stating:
I don’t think there's any reason to reject out of hand the kind of argument that Hoppe tries to give; on the contrary, the idea that there might be some deep connection between libertarian rights and the requirements of rational discourse is one I find attractive and eminently plausible. [...] But I am not convinced that the specific argument Hoppe gives us is successful.
A political theorist has concluded in a doctoral dissertation on the political philosophy of several Austrian economists that Hoppe has not provided any non-circular reasons why we "have to regard moral values as something that must be regarded as being established through (consensual) argument instead of 'mere' subjective preferences for situations turning out in certain ways". In other words, the theory relies on "the existence [of] certain intuitions, the acceptance of which cannot itself be the result of 'value-free' reasoning."
Mainstream libertarian philosophers reject Hoppe’s argument. Jason Brennan argues:
For the sake of argument, on Hoppe’s behalf, grant that by saying “I propose such and such,” I take myself to have certain rights over myself. I take myself to have some sort of right to say, “I propose such and such.” I also take you to have some sort of right to control over your own mind and body, to control what you believe. (Nota bene: I don’t think Hoppe can even get this far, but I’m granting him this for the sake of argument.). All I need to avoid a performative contradiction is for me to have a liberty right to say, ‘I propose such and such.’ I need not presuppose I have a claim right to say ‘I propose such and such.’ Instead, at most, I presuppose that it’s permissible for me to say, ‘I propose such and such’. I also at most presuppose that you have a liberty right to believe what I say. I do not need to presuppose that you have a claim right to believe what I say. However, libertarian self-ownership theory consists of claim rights… Hoppe’s argument illicitly conflates a liberty right with a claim right, and so fails.” 
- Hoppe, Hans-Hermann; Murray N. Rothbard; David Friedman; Leland Yeager; David Gordon; Douglas Rasmussen (November 1988). "Liberty Symposium" (PDF). Liberty. 2.
- Kinsella, Stephan (March 13, 2009). "Revisiting Argumentation Ethics". Mises Economics Blog. Ludwig von Mises Institute.
- Hoppe, Hans-Hermann (September 1988). "The Ultimate Justification of Private Property" (PDF). Liberty. 1: 20.
- Hoppe, Hans-Hermann (20 May 2002). "Rothbardian Ethics". LewRockwell.com. Retrieved 6 February 2012.
- The Ultimate Justification of the Private Property Ethic. Hans Hoppe
- Punishment and Proportionality: The Estoppel Approach. N.S. Kinsella
- Kinsella, Stephan (19 September 2002). "Defending Argumentation Ethics: Reply to Murphy & Callahan". Anti-State.com. Retrieved 9 February 2012.
- Rothbard, Murray N. (November 1988). "Beyond Is and Ought". Mises.org. Retrieved 14 October 2012.
- Murphy, Robert P.; Callahan, Gene (Spring 2006). "Hans-Hermann Hoppe's Argumentation Ethics: A Critique" (PDF). Journal of Libertarian Studies. 20 (2): 53–6. Retrieved 9 February 2012.
- "Comment on Hoppe / Comment on Osterfeld" (PDF). Austrian Economics Newsletter. 1988. Retrieved 14 October 2012.
- Long, Roderick T. "The Hopperiori Argument".
- J. Mikael Olsson, Austrian Economics as Political Philosophy, Stockholm Studies in Politics 161, p. 157, 161.
- Van Dun, Frank (January 1, 2009). "Argumentation ethics and the philosophy of freedom". Libertarian Papers. Retrieved May 8, 2013.
- Stephan Kinsella, Argumentation Ethics and Liberty: A Concise Guide
- J. Mikael Olsson (2015) Austrian Economics as Political Philosophy, Stockholm Studies in Politics 161.
- Argumentation Ethics and Liberty: A Concise Guide
- Collection of publications regarding argumentation ethics
- The A priori of Argumention, video introduction by Hoppe
- The Social Theory of Hoppe, on-line course by Stephan Kinsella.
- Eabrasu, Marian (2009). "A Reply to the Current Critiques Formulated Against Hoppe's Argumentation Ethics". Libertarian Papers. 1.