Many private-property rights advocates, libertarians and non-libertarians, sadly, stopped searching for the rational basis for the ethical validity of them. All arguments mostly come down to the fact that respecting private property leads to a better standard of living in comparison to systems where that is not the case; the fact that most people prefer a better standard of living; and therefore libertarianism should be very popular. But this line of reasoning can persuade only those who already accepted the "utilitarian" goal of increasing overall wealth. For those who don't have the same goals, libertarianism would be based on faith.
Of course, pure faith is not enough in political discourse, for that reason, I think that we need reason and logic. Natural rights tradition can be justified in the end, but only with arguments that arise from it, a model in which we justify tradition of private property is offered by Ludwig von Mises and his idea of praxeology and praxeological proof.
What is praxeology? Studying human behavior that can be understood a priori, that is praxeology deals with the conceptual analysis and logical implications of human choice. Unlike empirical science, like physics, chemistry or biology that is based on observation, praxeological conclusions are derived from logical deduction or discursive reasoning. Laws that are derived from praxeology are necessarily true and universal because they are logically implied by simple and undeniable facts. What is an undeniable fact? A fact where every attempt to negate it, proofs it is true. Once we state such a fact, we can derive further facts that are also true and valid for all. As long as implied arguments are valid and their premises based on initial undeniable facts, the validity of every argument in our "logical chain" is also true. The starting point of praxeology is an undeniable fact, and that fact is: "Every human action is a purposeful behavior". From that undeniable fact, all praxeology as a science is deducted. This undeniable fact or axiom is undeniable because every attempt of its negation is also a purposeful behavior. From this, it's obvious why logical deduction is an only method that we need to get to this conclusion.
For most people, this kind of approach "does not feel right", especially because we throw out empiricism or induction. But there is no reason for discomfort, primarily because of the difference between objects that science deals with like chemistry and psychics (that can study rocks, planets, atoms and similar) and unique characteristics of humans, one of those we stated earlier and that is that human activity is a purposeful behavior. People have goals and preferences, and they try to attain them, on the other side - atoms, planets or rocks don't have any goals or preferences, they cannot change opinion, they can only move or not move for example. That is why science can classify natural phenomena to their smallest detail, they can be measured and ranked. People, on the other side, cannot be classified, measured or ranked. Every day people change, they change their goal and they change their opinion on various things. People can't be "predicted" because they have their minds and capacity for learning and making choices.
The axiom of human action is logically inevitable when studying human behavior. There attempts of scientists that claimed that methods used in natural scientists are the only valid way for coming to conclusions about man and reality, but it is obvious how futile their attempts are, they are in contrast with the axiom. What is also obvious is, how praxeology "understands" uniqueness of every person and explanations praxeology can get us to are also limited by that fact.
All statements, true or false, indeterminable, meaningful, ambiguous, complete or incomplete are made due to some kind of argumentation.
The truth in this proposition cannot be disputed without falling into contradiction, because every attempt to deny it is a form argument. From this, we have a priori of every argumentation.
Argumentation is just a set of free-floating sounds but a human activity, that is an activity that has some kind of purpose and it uses physical means - the body of a person and various outside things - to attain a certain goal: agreement in relation to the validity of some proposition or argument.
Even if they are motivated by some initial disagreement, discussion or conflict that deals with validity of some claim, argumentation between proponent and opponent is by itself a form of interaction free of any conflict, voluntary and peaceful and its goal is to solve starting or initial disagreement and attaining a common answer to validity of some proposition or argument.
The validity of norms and rules of action that are necessary to even have an argument - praxeological propositions, that is prepositions by which we can determine the purpose of human action - cannot be disputed without falling into some form of pragmatic or performative contradiction.
Praxeological prepositions of argumentation, that is - prepositions that make argumentation a specific form of activity that has a goal of determining a truth value are two-fold: a) every person has to have exclusive rights over his body (the very fact that only that a person and only that person can control it) in a way that is independent of others and make its own conclusions, i.e. autonomous. and b) from the same reasons - mutually independent positions and autonomy, both - proponent and opponent have to have right to their previous property i.e. exclusive control of others, outside means of action attained indirectly from them before and independently from each other before the argument.
Every contrary argument: like that proponent of opponent have no right of exclusive ownership over his own body and his property cannot be defended without falling into some kind of pragmatical or performative contradiction. By argumentation, proponent and opponent demonstrate their goal which is finding a peaceful, conflict-free solution of a disagreement that started the argumentation in the first place. Negation of rights of self-ownership and previous property means negation of its autonomy and his independent stand in argumentation. Instead of that, it confirms dependence and conflict, that is heteronormativity, more then conflict-free and autonomously achieved agreement which is contrary to the very purpose of argumentation itself.
By being alive and by being capable of making arguments, we demonstrate that any ethical view on property rights except the libertarian one is invalid. If that is not the case, every other person has a right to our property, in a case when the property is defined subjectively, no-one could survive as an independent arbiter in any point in time. Consequently, no-one could state any kind of valid claim. Libertarianism is just an attempt to spread the principle of "non-aggression" to all institutions, including the State, libertarians think that there should be no people that are excluded from moral principles that we generally follow.
