Ludwig von Mises Institute · CC BY-SA 3.0

Ludwig von Mises argued, against most of twentieth-century economics, that economic laws could be derived deductively from the fact of human action rather than measured statistically — a method he called praxeology, laid out fully in his 1949 treatise Human Action. An Austrian economist who left Europe for the United States in 1940, he became one of classical liberalism's most uncompromising defenders of markets against central planning, and, largely through the students who carried his ideas forward, shaped both the Austrian school of economics and modern libertarianism.