A Theory of the Firm with Non-binding Employment Contracts
研究工人虽未工会化但拥有议价能力时的雇佣关系，分析非约束性合同和替换工人机会下的动态模型，发现唯一稳态均衡存在低效过度就业，而利润最大化均衡接近高效。
This paper examines an employment relation in which individual workers enjoy some bargaining power vis-a-vis the firm although they are not unionized. The main elements of the situations studied here are that the employment contracts are non-binding across periods of production and that the firm has opportunities to replace workers. The paper analyzes a dynamic model in which the processes of contracting and recontracting between the firm and its workers are intertwined with the dynamic evolution of the firm's workforce. The analysis of the model is somewhat complicated because the employment level is a nondegenerate state variable that evolves over time and is affected by past decisions. The main analytical results characterize certain important equilibria: the profit maximizing and stationa˙ry equilibria. The unique stationary equilibrium is markedly inefficient: it exhibits inefficient over-employment and the steady state wages coincide with the workers' reservation wage. It confirms earlier results derived by Stole and Zwiebel (1996a,b) in the context of a static model and shows that they are very robust even when the firm has nearly frictionless hiring opportunities. In contrast, in the profit maximizing equilibrium the outcome is nearly efficient and the wage exhibits a mark-up over the reservation wage.