He was one of the most important economists and political philosophers of the 20th century. He was one of the most important members of the Austrian School of economics. He also had many ideas in the fields of jurisprudence and cognitive science. He shared the 1974 Nobel Prize in Economics with his rival Gunnar Myrdal. The award was for their work in the theory of money and economic fluctuations; also for their analysis of the inter-dependence of economic, social and institutional phenomena. He also received the U.S. Presidential Medal of Freedom in 1991. He is thought to be one of the major causes of change from the Keynesian policies of the first part of the 20th century. Instead of governments handling the details of the economy, they went back towards classical liberalism in the 1980s and later. This happened most clearly in the 1980s in the U.S.A. (under Ronald Reagan) and the U.K. (under Margaret Thatcher).