La contrainte budgétaire lâche et la théorie économique[Soft Budget Constraint and Economic Theory]

The budget constraint as a bookkeeping identity is a fundamental concept of standard microeconomics. Clower reinterpreted this concept as a rational planning postulate. The notion of soft budget constraint (SBC), formulated for the first time by Janos Kornai (1979) in the context of a socialist economy is a heresy according to standard microeconomics and Clower, since budget constraint is by definition hard. Nevertheless, this concept is now applied in the analysis of post-socialist transition, emerging and developing countries, as well as developed capitalist economies. During the last fifteen years, the universal feature of the SBC motivated a formalised representation of this phenomenon in the framework of asymmetrical information literature. Hence, the SBC is reduced to a time inconsistency problem, namely the lack of credible dynamic commitment by the principal. The SBC is thus incorporated in new microeconomics and loses its institutional specificity. On a theoretical level, this removal of institutional specificity impoverishes the concept of SBC and brings us to reconsider the premises on which the original theory has been founded and to question the theoretical contradictions and tensions in Kornai’s works, from its beginning, which impeded the emergence of a more coherent institutional theory of the SBC.