On Wikipedia, a quarrel over this sentence:
Most members of libertarian parties support low taxes and a balanced budget because they believe citizens should keep most of the money they earn, while logically consistent libertarians, including anarcho-capitalists, refuse all methods to subject people to tax.
The words logically consistent were inserted by Irgendwer (German for anywho), who objects to replacing them with radical or even other. While any taxation is obviously inconsistent with the letter of the nonaggression principle, I do not agree that the NAP is the only coherent foundation for libertarian policy; two proofs of the same theorem need not resemble each other. (See also.) I see nothing logically inconsistent in the minarchist opinion that an anarchic order cannot keep the burden of crime below that of crime-plus-tax in a well-conceived low-tax state, and thus that such a state minimizes coercion (which is undesirable even if not the fundamental sin). I’m an anarchist not because I believe such a state is logically impossible but because I believe it is practically impossible: to prevent such a state from mutating into a predator is a prohibitively difficult engineering problem, which does not lend itself to empirical tinkering.
Some libertarian writers worry too much about the deficiencies of either NAP or utilitarianism in extreme cases. In the absence of divine revelation, moral philosophy makes more sense as an empirical science than as an axiomatic one like mathematics (or theology!). It’s a bit incongruous to insist on individualism, whose moral force comes from our observable differences, and on an axiomatic approach, which must abstract away some of those differences.
An empirical science infers the axioms (laws of nature) from the “theorems” (phenomena), and tests them by attempting to derive the latter from the former. If the derivation fails, the scientist asks where was the flaw in my reasoning? and the engineer asks is this approximation good enough to work with until a better one comes along? As a citizen (by which I mean a member of a civilization) seeking to live a moral life, I am more engineer than scientist; I find the nonaggression principle both “close enough” and conveniently simple. And the Coase principle suggests that wherever nonaggression is not “close enough” the deficiency is not the end of the world.
Thus spake the insomniac, who hopes no one was overly bored by it.