Comportement humain et rationalités dans les pays en développement

The application of marginalist instruments for understanding the behaviour of Southern individuals has always met numerous oppositions. According to them, the rationality claimed by the neo_classical theory is not convenient for studying these non_western societies and the underlying psychological hypothesis (homo oeconomicus) is completely unsuitable for explaining individual motivations. The present article proposes to examine these two criticisms. First of all, reviewing the definition of rationality, we underscore the existence of two very different definitions of "rationality",applying not at all to the same field of research. One generic (formal) definition of rationality which is "philosophically and psychologically neutral" [Malinvaud], expressing merely a certain coherence of choice. Following in Sen's footsteps, we illustrate moreover that this coherence of choices is very little constraining insofar as it is not verifiable. However marginalist analysis provides also definitions of rationality which are more concrete (substantial). They definitely ascribe a very restrictive vision to human motivation, one of them being the famous homo oeconomicus. The non_psychological dimension of rational choice (formal definition) is dedicated to the study of social interaction, whereas the psychological dimension of rational choice (substantial definition) focuses on the individuals'motivation, on what makes them act. These two levels of analysis are therefore radically different, but they are often confused.This confusion explains why many economist are getting into psychology without noticing it...Secondly, we show that the restrictive image of the homo oeconomicus still has a great explanatory fertility for conveying the choices of Southern individuals. One therefore has to adapt the satellite hypothesis of our models and envisage with more attention the context in which individuals make their decisions. By taking into account certain important characteristics of the external environment of developing contries, namely the very imperfect functioning of the markets, this approach makes it possible to discover the subtle forms taken on by the economic motives of Southern individuals. Despites the fact that the complexity and the specificity of traditional societies disturb the perception of elementary economic stakes, this approach has an undeniable explanatory power. (Full text in French)