The other great modern luminary of anarcho-capitalism is David D. Friedman. Also an economist by training, Friedman takes a value-free consequentialist approach to the subject rather than Rothbards natural rights approach. Not that Friedman is amoral by any means - he certainly has libertarian values - but feels that insofar as convincing others that a free society is better, a descriptive explanation is more efficacious. People that don't consider natural rights to exist, or are skeptical of any consensus about morality, may be convinced by practical economic results. Rothbard and Friedman could be considered the modern analogy to Spooner and Tucker.
Friedman points out that a free society may not be libertarian, but he believes that it would have a bias for libertarianism. For example, while people will vote for various restrictions of the liberty of others when the cost is borne to the general public, they are less likely to do so when they bear due share of the costs. He gives marijuana prohibition as an example: Given a costless choice "should we allow people to smoke pot," they may say "yes," but putting the question as "would you pay an extra $200 a year to prevent others from smoking pot" the answer may well be "no."
The economic aspects of law is of particular interest to Friedman. He has written much on market-generated law, the efficiency of law, and historical examples of non-statist law such as the "Thing" system of classical Iceland.
Friedman's book The Machinery of Freedom: Guide to a Radical Capitalism (1971) is a classic of libertarian literature. It is both an immanently entertaining economics book and a mind-opening view of the anarchist idea.
The purpose of this book is to persuade you that a libertarian society would be both free and attractive, that the institutions of private property are the machinery of freedom, making it possible, in a complicated and interdependent world, for each person to pursue his life as he sees fit." - David Friedman, introduction to Machinery of Freedom