Bertrand and Walras Equilibria under Moral Hazard
研究道德风险下竞争模型，发现当偏好非可分时，伯特兰竞争可能产生正利润，且瓦尔拉斯一般均衡可能不存在，必须包含配给。
We consider a simple model of competition under moral hazard with constant return technologies. We consider preferences that are not separable in effort: marginal utility of income is assumed to increase with leisure, especially for high income levels. We show that, in this context, Bertrand competition may result in positive equilibrium profit. This result holds for purely idiosyncratic shocks when only deterministic contracts are considered, and extends to unrestricted contract spaces in the presence of aggregate uncertainty. Finally, these findings have important consequences upon the definition of an equilibrium. We show that, in this context, a Walrasian general equilibrium a la Prescott-Townsend may fail to exist: any ’equilibrium ’ must involve rationing. 1.