Human Action: A Treatise on Economics is a work by the Austrian economist and philosopher Ludwig von Mises. Widely considered Mises' magnum opus, it presents the case for laissez-faire capitalism based on praxeology, his method to understand the structure of human decision-making. Mises rejected positivism within economics, and defended an a priori foundation for praxeology, as well as methodological individualism and laws of self-evident certainty. Mises argues that the free-market economy not only outdistances any government-planned system, but ultimately serves as the foundation of civilization itself.