David Director Friedman is an American economist, physicist, and legal scholar. He is known for his textbook writings on microeconomics and the libertarian theory of anarcho-capitalism, which is the subject of his most popular book, The Machinery of Freedom. Described by Walter Block as a "free-market anarchist" theorist, Friedman has also authored several other books and articles, including Price Theory: An Intermediate Text (1986), Law's Order: What Economics Has to Do with Law and Why It Matters (2000), Hidden Order: The Economics of Everyday Life (1996), and Future Imperfect (2008).