J. C. Lester is a philosopher specializing in libertarianism. Apart from articles, dialogs, and book chapters—many available online—he is the author of Escape from Leviathan: Libertarianism without Justificationism (paperback 2012) and Arguments for Liberty (2011).

In his post on pollution and the non‐​aggression principle, Matt Zwolinski begins by telling us that “Libertarians generally believe that aggression against innocent persons is morally wrong, and that the only just use of violence is to prevent aggression by others.” Somewhat less imprecisely, we might say that the only just use of coercion (using force and the threat of force against people) is to prevent or redress aggression.

He then says, “In this respect, at least, the liberal egalitarian philosopher John Rawls was on precisely the same page as his libertarian colleague, Robert Nozick” and quotes Rawls on “freedom” purportedly to that effect. However, Rawls has an understanding of “freedom” that is inherently political and which sanctions much that libertarians would rightly see as itself involving aggression. Consequently, Rawls and Nozick are certainly not “on precisely the same page”.

We are soon asked, “Suppose I aggress against you not by beating you over the head with a club, but by blowing tobacco smoke into your face? The smoke‐​blowing, just like the clubbing, is a physical invasion of your body. And it is a harmful invasion.” And here we should note that the physical harm itself is irrelevant to liberty. What matters is that the victim disvalues the invasion for whatever reason. If an aggression were to improve the victim’s health, then it would still flout his liberty.

After such considerations, Zwolinski concludes that “The consistent application of Rothbard’s absolutist principle of non‐​aggression thus seems to require a prohibition on all forms of non‐​consensual pollution.” And in its absolutist form I agree. However, this overlooks something crucially important: it cuts both ways. The enforcement of the prohibition would itself aggress against the people whose activities would produce the pollution (e.g., having fires for needed warmth and cooking). So such prohibitions cannot be allowed either. We have reached not one but two unacceptable conclusions and, more to the point, they amount to an inconsistency in the “absolutist” version of the theory. Hence that form of the theory is a priori refuted. (I know that Rothbardians try to introduce various points to solve such problems, but they look ad hoc and invalid to me.)

There are two main problems with the absolutist theory that lead to this result. First, while liberty itself can be interpreted as the absence of aggression, the libertarian policy must be to minimize aggression when there is such a clash as that described. Thus some sort of compromise is required, maybe with some damages being paid in one or the other direction. Second, “aggression” understood in terms of violating property rights is only a rule of thumb. “Aggression” can be more abstractly and accurately theorized as proactively imposing costs (such as both pollution and pollution prohibitions) on other people. This pre‐​propertarian theory is required for consistently solving such property problems, paradoxes, and inconsistencies whenever they occur.

This alternative approach should become clearer and more cogent as I reply to Zwolinski’s final essay, in which he attempts to refute the “non‐​aggression principle” beyond any salvation.