ABSTRACT
Few economists would deny that the rationality principle plays a fundamental role in economics and in all social sciences, but the nature of this principle and the way it operates in economics are far from consensual. Though this principle was more or less explicitly defined by various authors, it remains almost impossible to characterize it in a way that can be generally accepted as fully satisfactory.1 Of course, one can say that it is the principle according to which people are rational, but rational in what sense? What kind of rationality should one have in mind when maintaining that this principle plays such a significant role? It is true that most economists would answer this question with the help of an apparently crystal clear concept, either maximization or consistency. But these notions referred to in economic models should be considered as idealizations of a certain rationality that is attributed to actual agents who make decisions and perform actions. Therefore, when they are engaged in a debate that forces them to refer to human rationality as such, economists usually realize how hard this notion is to encapsulate. To mention only one example, in his debate with Daniel Kahneman, Charles Plott observed that the concept of rationality ‘lacks scientific precision and as a result is a source of needless controversy and misunderstandings’ (Plott 1996b: 220). How can we characterize this rationality which presumably guides human actions? Are agents making their choices in such a way that they maximize their utility in each or most of their choices? Are they maximizing this utility according to an objective measure or simply according to what they consider to be useful for them? Are they simply disposed to act in ways that they judge appropriate according to the circumstances? What kind and what amount of information is required to allow agents to make such relatively appropriate choices? Are we assuming that their expectations are based on the conclusions of the most reliable economic theories? Should we postulate that they themselves are in a position to rationally impute choices to other players in economic games in order to choose accordingly? Are they managing to be consistent in all of their choices or are they rather trying to optimally adapt themselves to changing situations irrespective of their previous choices? Should we consider that agents change their minds and adapt their choices to new situations only when the prevailing situation becomes unbearable in such a way that they simply manage to remain in a satisfying situation?
