Rakás · CC BY-SA 4.0

Developed the theory of games of incomplete information — so-called Bayesian games — giving economists a rigorous way to model decisions made without knowing an opponent's full hand, work that extended game theory's reach into political and moral philosophy as well as economics. He also contributed to the study of equilibrium selection and utilitarian ethics. Harsanyi shared the 1994 Nobel Memorial Prize in Economic Sciences with John Nash and Reinhard Selten, having emigrated from Hungary to the United States in 1956.