Contenu du sommaire : Quelles hypothèses de rationalité pour la théorie économique?

Individual rationality cannot be defined independently of the type of social organisation. Two different meanings must be considered. The first, quite usual, is the maximisation of a function under some constraints. It is shown that this hypothesis, crucial for the normative content of general equilibrium theory, is relatively immaterial for its descriptive aspect. The second, often overlooked, concerns the rules under which individuals carry out their transactions. A monetary organisation of markets possibly is one of theses rules. Introducing a monetary system in current nontâtonnement models of the market entails that an individual cannot be sure that his participation in the market will always improve his situation. If money and market were indissociable, the fiction according to which society results from voluntary actions of rational agents would be deprived of any analytical foundations.

Always associated to a purposive behavior, the economic rationality is often confused with the utility maximizing behavior. This association is not always valid, since the maximizing form of individual rationality is not indépendant from its social context. This article deals with the link between the rationality of the individual behavior and the structure of the social organization, using the interdépendant couple "Rule of Behavior" - "Rule of Organization" . Three different models are presented : maximizing rationality and walrassian market , improving rationality and edgeworthian market , teleologic rationality and marshallian market .

Several cases of alleged irrational behavior are examined : imitation of others in a situation of uncertainty ; non-rational revision of belief in a case of cognitive dissonance ; sunk cost fallacy ; weakness of the will. A general characterization of this class of behavior is provided : the agent endowing herself with a power over the past and observing herself as from the outside. These two features are shown to characterize the evi- dentialist choice in Common Cause Newcomb Problems, from Fisher's smoking case to Max Weber's paradox. The rationality of evidentialism is nevertheless advocated. It is furthermore shown that the Backwards Induction Paradox is a Newcomb problem. The rationality and possibility of reciprocal exchange in a case of non-credible promise follows.

Instrumental reason develops during the utilitarianism period by rejecting successively three sorts of internal limit or blind point wich classical "platonician" or "intuitionist" reason ascknowledged when defining its practical form. These limits concern the passions, the. will and the jug- ment of meaning formulated by the spectator to whom each actor adresses himself

"Economies will progress as we deepen our understanding of human thought processes ; and economics will change as human individuals and human societies use progressively sharpened tools of thought in making their decisions and designing their institutions . A body of theory for procedural rationality is consistent with a word in which human beings continue to think and continue to invent ; a theory of substantive rationality is not" (HA. Simon, 1976, p, 146). Has'nt this strong conclusion of HA. SIMON to be seriously examined and discussed, particularly try Economics sciences ? Considering some of the main stages of the history of the concept of Rationality in the scientific thought, (Pre- socratics and Aristotle, R. Descartes and G.B. Vico, G. Boole and f.B. Grize...), the legitimity and the scope of the distinction proposed by HA. Simon between the two forms of rationality, "Substantive" and "Procédurale" are argumented. It is shown that the first one gives account of the deductive or syllogistic forms of reasoning as express today by the "formal logics", (based on the three axioms of syllogism formulated by Aristotle, usually with a confusion between formal Negation and meaningful Contradiction) ; and that the second one take in account the dialectical and rhetorical forms of reasoning, as expressed today by the "natural logics", based on some hypothesis of conjonctive and teleological plausibility and feasibility. The consequences of this distinction for the modeling of complex systems and of design of intervention in complex systems are briefly considered.

In response to Pr. Le Moigne's paper, my contribution stresse the originality and importance of Simon's approch to decision making in terms of bounded rationality. There is no doubt that any interesting view of rational decision-making should take into account the procedural aspects of human cognitive processes stressed by the simonian school. Nevetheless, it is here argued, the very principle of "satifiyng", at the heart of Simon'sview, in perhaps less... satisfactary than his followers usually claim. This paper tries to argue that a doctrine of imperfect rationality, grounded in the popperian concept of "situational analysis", can cope with some of the simonian intuitions without taking the radical step of abandonning the useful instrument of optimization.

The definition of SIMON on the one hand and the analysis of LE MOIGNE on the other leads us to oppose rational and procedural rationality. Beyond the differences in the cognitive and logical frameworks, it is maintained that this rationalities correspond to two different representations of the economy, one of which defines it as a mechanical system of markets and the other as a population of organisations. In terms of a problematic of behavior, however, both representations fail to convey the compexity of the social bond.

Based on a strong version of the concept of cooperation this paper explores several interpretation of such behavior within organizations. Section I is focused on the technological explanation and some of its extensions. In section II, models are examined where the standard rationality assumption is relaxed. Section III discusses some rationale to cooperation that can be provided by transaction costs economics. Confronted to some radical insufficiencies of these explanations, section IV suggests, with some testable propositions, to consider the problem from a different perspective. Cooperating should be understood as rooted within a structural characteristic of organizations, based on stable patterns of behavior -. the incentive te share.

According to B. Walliser, the economic rationality has two aspects : 1) instrumental (aiming at some goal, e.g. maximizing utility), 2) cognitive (building models for anticipating). This thesis throws some light on the field, so controversial, of human action by giving the basic keys to map it out. It also opens potentially fruitful perspectives by helping to explicit what the rational expectations idea presupposes. But, moving on along this line, one has to deal with an epistemological difficulty which lies at the very foundations of the conception of economic agents as model-builders.

Economists apply sometimes Game theory to social norms analysis. In this framework norms are viewed as strategic equilibria in non corporative games. But instrumental rationality, that is supposed to rule individual action, faces a clear limit relative to the explanation of nom emergence. To Select his best response, everyone would like to be, ideally, the last one ta play, after everyone. In this respect, for someone to comply with the norm, it ought to be the case that everyone yet comply with the norm. In other words, norms may emerge whenever they already exist. . . Those remarks shed light, by contrast, on the fact that norm guided action requiers some autonomy and capability to take initiative on the part of individuals.