Nozick defended a minimal state. Some libertarians thought he had stopped one step too soon, while others, starting from self-ownership, reached conclusions far to the left of his.

Anarcho-capitalism

The American economist Murray Rothbard (1926 to 1995), a student of the Austrian economist Ludwig von Mises, popularized the term anarcho-capitalism. He drew on nineteenth-century American individualist anarchists such as Lysander Spooner and Benjamin Tucker, and on the Belgian-French economist Gustave de Molinari, who argued in 1849 that security could be supplied by competing firms.

Rothbard's starting point was the non-aggression principle: no one may initiate or threaten force against another person or their property; force is permitted only in defense. Judged by that rule, Rothbard argued, the state is an aggressor on a vast scale: in his view taxation is a form of theft, and conscription a form of slavery. If the state's useful services are worth having, he reasoned, they can be provided voluntarily.

Private defense and law

The boldest anarcho-capitalist proposal is to provide police and courts privately. People would subscribe to competing protection agencies and courts, perhaps through insurance. When agencies disagreed, they would settle disputes by arbitration because fighting is expensive and bad for business. Law could develop the way medieval merchant law and parts of the common law did, through custom and judges' decisions. The economist David Friedman, in The Machinery of Freedom (1973), made a case based on results rather than rights, and studied medieval Iceland, where for roughly three centuries law was enforced largely by private parties rather than by a government executive.

Left-libertarianism

“Left-libertarian” has two common uses. In academic philosophy, it names theories, defended by writers such as Hillel Steiner, Peter Vallentyne and Michael Otsuka, that combine full self-ownership with egalitarian ownership of natural resources. You own yourself, but no one made the land, so those who claim more than their share owe compensation to others. The idea has older roots. Thomas Paine's Agrarian Justice (1797) proposed a fund, raised by a tax on inheritances, that would pay every person a lump sum at age twenty-one and a pension in old age, as compensation for the loss of a natural share in the land. Henry George's Progress and Poverty (1879) proposed a single tax on the value of land.

More broadly, “left-libertarian” also covers libertarian socialists and anarchists who oppose both the state and capitalism, including market anarchists in Proudhon's line who want free exchange without bosses or landlords.

The great debates

• Property. Right-libertarians see private property as an extension of self-ownership and a bulwark of liberty. Left anti-statists argue that large holdings of land and capital exist only because states enforce them, and that they give owners power over others. Tucker, for example, accepted ownership based on occupancy and use, not absentee landlordism.
• Markets. Anarcho-capitalists embrace fully free markets; mutualists accept markets but not capitalism; anarchist communists reject markets and money altogether.
• Equality. Right-libertarians defend equal rights before the law and accept the inequality that free exchange produces. Left anti-statists ask whether a worker who must accept a job or go hungry is really free, and argue that liberty requires rough material equality.

The deepest quarrel is over the name itself. Many traditional anarchists deny that anarcho-capitalism is anarchism at all, because they regard bosses and landlords as rulers too. Anarcho-capitalists reply that voluntary agreements are not rule, and that theirs is the only consistent opposition to coercion.

Worked example: the company town

Imagine a remote valley with no government. A mining company owns all the land, the houses, the only store and the security force. Workers came voluntarily for high wages, but rents and store prices are high too, and leaving means a long and expensive journey.

An anarcho-capitalist asks first whether anyone's rights were violated. If the company acquired the land legitimately and workers signed contracts freely, the arrangement is just, even if unattractive. She adds that in an open market other firms could build competing stores and housing, and workers could hire their own protection agency if the company's guards abused them.

A left-libertarian questions the starting point. Who gave the company the whole valley? If natural resources belong to everyone in some egalitarian sense, the company owes the community for what it took, which might fund the workers' freedom to leave or to bargain.

An anarchist communist sees the company as a private state: it makes the rules, owns the guns and controls people's food and shelter. Removing the government changed nothing if the company now rules instead. Her remedy is for the workers to take over the mine and the store and run them in common.

A critic of both notes that the valley shows the problem of private defense: the agency with the most guns belongs to the strongest party. All three anti-statists must answer how the weak are protected when one actor controls everything, which is where the next level begins.