an opponent of the Austrian tradition which led from Carl Menger and Böhm-Bawerk through Mises to Rothbard. Austrian economist Walter Block says that the Austrian School can be distinguished from other schools of economic thought through two categories—economic theory and political theory. According to Block, while Hayek can be considered an Austrian economist, his views on political theory clash with the libertarian political theory which Block sees as an integral part of the Austrian School. Both criticism from Hoppe and Block to Hayek apply to Carl Menger, the founder of the Austrian School. Hoppe emphasizes that Hayek, which for him is from the English empirical tradition, is an opponent of the supposed rationalist tradition of the Austrian School; Menger made strong critiques to rationalism in his works in similar vein as Hayek's. He emphasized the idea that there are several institutions which were not deliberately created, have a kind of "superior wisdom" and serve important functions to society. He also talked about Burke and the English tradition to sustain these positions. When saying that the libertarian political theory is an integral part of the Austrian School and supposing Hayek is not a libertarian, Block excludes Menger from the Austrian School too since Menger seems to defend broader state activity than Hayek—for example, progressive taxation and extensive labour legislation. Economists of the Hayekian view are affiliated with the Cato Institute, George Mason University (GMU) and New York University, among other institutions. They include Peter Boettke, Roger Garrison, Steven Horwitz, Peter Leeson and George Reisman. Economists of the Mises–Rothbard view include Walter Block, Hans-Hermann Hoppe, Jesús Huerta de Soto and Robert P. Murphy, each of whom is associated with the Mises Institute and some of them also with academic institutions. According to Murphy, a "truce between (for lack of better terms) the GMU Austro-libertarians and the Auburn Austro-libertarians" was signed around 2011. Influence Many theories developed by "first wave" Austrian economists have long been absorbed into mainstream economics. These include Carl Menger's theories on marginal utility, Friedrich von Wieser's theories on opportunity cost and Eugen Böhm von Bawerk's theories on time preference, as well as Menger and Böhm-Bawerk's criticisms of Marxian economics. Former American Federal Reserve Chairman Alan Greenspan said that the founders of the Austrian School "reached far into the future from when most of them practiced and have had a profound and, in my judgment, probably an irreversible effect on