I define anarchist society as one where there is no legal possibility for coercive aggression against the person or property of any individual. Anarchists oppose the State because it has its very being in such aggression, namely, the expropriation of private property through taxation, the coercive exclusion of other providers of defense service from its territory, and all of the other depredations and coercions that are built upon these twin foci of invasions of individual rights.

"Society Without A State" in The Libertarian Forum (1975).