Abstract

It would be very difficult to discuss the question concerning the hypothesis of omniscience in microeconomics without relating this hypothesis to the more fundamental hypothesis of rationality (usually referred to as rationality principle or postulate) which is at the base of the very idea of an economic theory and even social sciences. Indeed omniscience is a quality which was typically attributed to homo oeconomicus whose essential characteristic is to be perfectly "rational". This association between omniscience and rationality goes back to the marginalist revolution which progressively brought economists to model economic agents as rational calculators who make each decision by systematically maximizing their utility through the standard application of more or less sophisticated mathematical methods. But since the very idea of such a maximization has no meaning if all relevant parameters and variables are not carefully taken into account, it became relatively common to associate omniscience (the required knowledge of such parameters and variables) and rationality (the disposition to make decisions which tend to maximize the degree of success in reaching a goal).