This volume explores the conceptual terrain defined by the Greek word eikos: the probable, likely, or reasonable. A term of art in Greek rhetoric, a defining feature of literary fiction, a seminal mode of historical, scientific, and philosophical inquiry, eikos was a way of thinking about the probable and improbable, the factual and counterfactual, the hypothetical and the real. These thirteen original and provocative essays examine the plausible arguments of courtroom speakers and the 'likely stories' of philosophers, verisimilitude in art and literature, the likelihood of resemblance in human reproduction, the limits of human knowledge and the possibilities of ethical and political agency. The first synthetic study of probabilistic thinking in ancient Greece, the volume illuminates a fascinating chapter in the history of Western thought.