This paper considers contractarianism as a method of justification. The analysis accepts the key tenets of contractarianism: expected utility maximization, unanimity as the criteria of acceptance, and social-scientific uncertainty of modelled agents. In addition to these three features, however, the analysis introduces a fourth feature: a criteria of rational belief formation, viz. Bayesian belief updating. Using a formal model, this paper identifies a decisive objection to contractarian justification. Insofar as contractarian projects approximate the Agreement Model, therefore, they fail to justify their conclusions. Insofar as they fail to approximate the Agreement Model, they must explain which modelling assumption they reject.

本文认为契约主义是一种辩护方法。该分析接受了契约主义的主要原则：期望效用最大化，一致作为接受标准以及建模代理人的社会科学不确定性。但是，除了这三个特征之外，分析还引入了第四个特征：理性信念形成的标准，即。贝叶斯信念更新。本文使用形式化模型确定了对契约论证理由的决定性反对。因此，只要合同项目接近协议模型，它们就无法证明其结论是正确的。只要他们不能近似协议模型，就必须说明他们拒绝哪种建模假设。