The recognition of the existence of imperfect information in decision making and the cognitive li mitations of the human mind put various assumptions of the neoclassic al economic paradigm in doubt. Neoclassical economists re-sponded by arguing that decision rules, or rules-of-thumb, can be used to render decision with-out processing information. Further, neoclassi-cists h ave suggested that rational rules compete against and drive out irrat ional ones. This paper focuses on the use of rules-of-thumb and posit s that the empirical evidence about the rationality of these rules is dubious and that they logically cannot serve as a basis for rational conduct. Copyright 1987 by WWZ and Helbing & Lichtenhahn Verlag AG
