ABSTRACT
Initially, the rationalist legacy of the eighteenth-century Enlightenment resulted in a very clear separation of reason from madness. The madman was characterized by a failure of deductive and inductive logical thinking. In the 1950s, however, this distinction disappeared when cognitive science brought to light a whole series of supposed failures of rational behavior in the normal individual as well. What dealt a serious blow to the theories of human decision making and judgment formation was the fact that several reasoning flaws that had been attributed solely to the psychiatric patient were, in fact, also found in the normal individual. Over the past few years, the theory that started with the Enlightenment seems to have reversed in a circular way. If we consider rationality as based on the logical coherence adopted in economic theory, then rationality is more apparent in individuals suffering from certain neurological and psychiatric disorders than among people without those diseases. Paradoxically, normality seems characterized by irrationality, and abnormality by rationality. Why this paradox? There is an anti-ecological bias at work here: behavioral irrationality is not assessed by its capacity to adapt to the real environment and to solve environmental problems. Instead, it is tested in abstract and artificial situations rather than the real world. The world to which the tests pertain is characterized by risk, but not uncertainty. The paradox lies in the fact that we do not consider the lesson from the theory of bounded rationality, aptly expressed by Herbert Simon’s metaphor of the scissors. Often the real environments have an unlimited range of possibilities because they are characterized by uncertainty or they have a limited range but they are computationally intractable. Therefore, the classical model of rationality, characterized by coherence with formal norms of logic, probability, and utility cannot be applied. Judgment of the rationality of human behavior does not depend on its conformity to some formal norm, but only on its cognitive success in given specific environmental tasks. The irrationality of the mental disorder is such that it differs from bounded ecological rationality because it would not allow some of the adaptive cognitive functions, summarized in a rigidity and impermeability to the signals from the environment and the lack of a realistic representation of the variables at work.
