从事前效率问题到事后效率问题--不完全合同理论的几类经典模型比较

From Ex ante Inefficiency to Ex post Inefficiency:Comparing Several Classical Types of Models of Incomplete Contract Theory

通过对不完全合同经典理论模型的组成要素的梳理和分类,本文首次将不完全合同理论的模型分为四种类型:行动事前不可缔约而事后可缔约的事前效率问题模型,行动事前和事后都不可缔约的事前和事后效率问题模型,事前部分可缔约的事前和事后效率问题模型,收益事后不可证实的事前和事后效率问题模型。这些不同的理论被纳入一个统一的框架中进行表述。传统的产权理论具有一些缺陷,而事后不可缔约的模型更适合研究权威、授权、科层等问题。相对于关于投资激励的事前效率问题,事后效率问题的来源要多得多。对事前与事后缔约性问题的探讨以及对事后效率问题的研究是丰富不完全合同理论发展的动力。

We classify the incomplete contract theory first to 4 types in terms of the ex ante and ex post contractibility and the ex ante and ex post inefficiency： ex ante inefficiency model with ex ante non-contractible but ex post contractible actions, ex ante and ex post inefficiency model with ex ante and ex post non-contractible actions, ex ante and ex post inefficiency model with partial- contractible actions, ex ante and ex post inefficiency model with ex post unverifiable payoffs. We analyze the difference and similarity of these models and compare what phenomena these models explain. The GHM model has been criticized for its assumptions, especially for the assumption of ex post contractibility. To analyze the topics of authority, delegation and hierarchy, we must depart from a world in which Coasian renegotiation always leads to ex post efficiency, and focus on the much more complex ex post inefficiency.