Of paramount importance to the natural sciences, the principles of Darwinism, which involve variation, inheritance, and selection, are increasingly of interest to social scientists as well. But no one has provided a truly rigorous account of how the principles apply to the evolution of human society—until now. In Darwin’s Conjecture, Geoffrey Hodgson and Thorbjørn Knudsen reveal how the British naturalist’s core concepts apply to a wide range of phenomena, including business practices, legal systems, technology, and even science itself. They also critique some prominent objections to applying Darwin to social science, arguing that ultimately Darwinism functions as a general theoretical framework for stimulating further inquiry. Social scientists who adopt a Darwinian approach, they contend, can then use it to frame and help develop new explanatory theories and predictive models. This truly pathbreaking work at long last makes the powerful conceptual tools of Darwin available to the social sciences and will be welcomed by scholars and students from a range of disciplines.