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, or rational investigation of human decision-making. It rejects positivism within economics. It defends an a priori epistemology and underpins praxeology with a foundation of methodological individualism and speculative laws of apodictic certainty. Mises argues that the free-market economy not only outdistances any government-planned system, but ultimately serves as the foundation of civilization itself.