Many libertarians erroneously believe that they, as a group, hold a natural monopoly on the concern for freedom, liberty and voluntary interaction. In fact, many in the movement think that these words alone, as objective and self-evident concepts, serve as a description of their ideology. After all, who the hell could consciously and openly hate freedom? Who could oppose the Philosophy of Liberty? It’s not uncommon to hear the less diligent among us express that they just want people to have freedom and act voluntarily, as if this could suffice as a defense of their ideas, and as if ‘freedom’ and ‘voluntary’ were not up to interpretation.

So what does it mean for something to be voluntary, then? Is it the presence of choice? In one sense of the word, every living person has at least a handful of choices in any given situation. If A presses a gun to B’s temple and demands his wallet, A has not made a decision for B; B still has choices. He can meet A’s demands and hand over his wallet, or he could attempt to physically resist and incapacitate A, or he could remain silent and still. There are many possibilities for B. The given set of choices in a situation may not be ideal—in this case, the choices are downright terrible—but choices still exist.

Most would agree that whether or not a choice is voluntary depends upon the circumstances in which the choice was made. Perhaps B’s actions are involuntary if A’s actions limit the range of possible choices B can make. Placing a gun to one’s head certainly does this. But there are many other actions A could take that would limit B’s choices. If A encloses and develops a few acres of land, B now does not have the option to use this land—A has limited B’s choices to exclude any use of this land. Despite this, I doubt voluntaryists will disavow propertarianism.

Any action one takes at least marginally limits the range of choices for every other human. Are there certain choices that need to remain available for an action to be voluntary and for man to be free? What about having the option to leave? Does the adage “If you don’t like it, you can leave” have any validity? Trying to define what is voluntary as a starting point results in a jumbled, confusing mess and is bound to make some arbitrary distinction. Alas, we see that in determining whether an act is voluntary, we must fall back on whether or not we see the circumstances as just or unjust.

As Jason Brennan writes, the idea that taxes are theft (i.e. involuntary transfer) is a conclusion, not a premise. In order to reach this conclusion, we must first prove that the State does not have a legitimate claim to at least a portion of its subject’s wealth. When one invokes the nonaggression principle, he begs the question. Even if we accept the nonaggression principle to be valid, the conclusion is not necessarily propertarian anarchism until we prove that the State acts only aggressively and that private property is voluntary. Whether or not all marketplace interactions are voluntary, whether or not the State is an aggressor, and whether or not anarchy is freedom depends on whether we can find private property and the State to be morally legitimate or illegitimate.

This becomes increasingly difficult—nay, impossible—if we reject the notion of an objective morality. If neither the State nor private property can be considered moral or immoral, then the interactions that follow as a result of their existence cannot be objectively described as voluntary or involuntary, and the condition of the people living in this society cannot be objectively described as free or unfree.

So long as there is difference in opinion over property or the State or self-ownership, there will be a reasonable case to be made that someone is acting violently enforcing his opinion (that is, aggressing) and someone is unfree. Libertarians ought to be aware of this before throwing around the words ‘voluntary’ and ‘freedom’ as if there were only one possible interpretation of these words.

EDIT: For a further, clear articulation of this idea, read this article, also by Jason Brennan, which I unfortunately only came across days after writing this.