No one may threaten or commit violence ('aggress') against another man's person or property. Violence may be employed only against the man who commits such violence; that is, only defensively against the aggressive violence of another. In short, no violence may be employed against a non-aggressor. Here is the fundamental rule from which can be deduced the entire corpus of libertarian theory.
Murray RothbardIt would be an instructive exercise for the skeptical reader to try to frame a definition of taxation which does not also include theft. Like the robber, the State demands money at the equivalent of gunpoint; if the taxpayer refuses to pay, his assets are seized by force, and if he should resist such depredation, he will be arrested or shot if he should continue to resist.
Murray RothbardThe libertarian creed...offers the fulfillment of the best of the American past along with the promise of a far better future. Libertarians are squarely in the great classical liberal tradition that built the United States and bestowed on us the American heritage of individual liberty, a peaceful foreign policy, minimal government, and a free-market economy.
Murray RothbardThe fundamental axiom, then, for the study of man is the existence of individual consciousness
Murray Rothbard