September 22, 1920-June 26, 1993
BY BRUCE BUENO DE MESQUITA AND KENNETH SHEPSLE
WILLIAM RIKER WAS A VISIONARY scholar, institution builder, and intellect who developed methods for applying mathematical reasoning to the study of politics. By introducing the precepts of game theory and social choice theory to political science he constructed a theoretical base for political analysis. This theoretical foundation, which he called “positive political theory,” proved crucial in the development of political theories based on axiomatic logic and amenable to predictive tests and experimental, historical, and statistical verification. Through his research, writing, and teaching he transformed important parts of political studies from civics and wisdom to science. Positive political theory now is a mainstream approach to political science. In no small measure this is because of Riker’s research. It is also a consequence of his superb teaching—he trained and influenced many students and colleagues who, in turn, helped spread the approach to universities beyond his intellectual home at the University of Rochester.
Bill, as he was known to his friends, was born in Des Moines, Iowa, on September 22, 1920. He was the much-