Precautionary savings: an element in the analysis of economic behavior and adjustments.

Summary This thesis, which consists of two parts, consists in understanding not only individual reactions in a risky environment but also their impact on the macroeconomic equilibrium. In the first part, we distinguish two research approaches: on the one hand, the standard approach of Von Neumann and Morgenstern. On the other hand, representations of the Kreps and Porteus type that allow us to introduce preferences with respect to the date of resolution of the uncertainty and to separate the notions of risk aversion and intertemporal substitution. We then propose an application of these preferences to the study of risk sharing in a production economy with uncertain returns. In fact, we find that the results do not really differ from those existing in a pure exchange economy. Finally, following the work of Leland (1968), we analyze the saving behavior of individuals faced with both income and return risks. Using the notion of prudence, we show that their reaction depends on the relative importance of these two risks. In the second part, we show the relevance of the precautionary motive in the analysis of the macroeconomic equilibrium. Using two studies, we show that additional conditions to those usual in partial equilibrium are required for aggregate precautionary savings to be formed in equilibrium. Moreover, other conditions are also required, notably on the factors of production, for the precautionary effect to prevail in equilibrium. By emphasizing the importance of the concept of precaution in the analysis of behavior, this thesis helps to show that this concept plays a significant role in explaining capital accumulation.