Human Action Is Purposeful Behavior

From Human Action: A Treatise on Economics (1949), the opening sentence of the book's first section. Mises used this deceptively simple statement as the foundation of his entire economic system — a methodology he called "praxeology," the science of human action. By defining action as purposeful behavior, Mises excluded reflexes and unintentional behavior and built a theory of economics grounded in individual choice rather than statistical aggregates.