法律权衡方法的形式理性——基于偏好聚合的分析

The Formal Rationality of Legal Balancing Methods—An Analysis based on Preference Aggregation

如何克服个案验证的局限,在一般性层面上准确、有效地评判权衡方法的方法论效用,是法律权衡理论面临的重要问题。社会选择理论在讨论集体决策时使用的“偏好聚合”视角,可从形式理性的面向为解答该问题提供线索。实例研究首先表明,法律权衡与集体决策共享偏好聚合的数学形式,二者的运作皆表现为从复数个体偏好向整体偏好的过渡。以此为桥梁,社会选择理论对集体决策悖论的分析,显示了形式理性同样对权衡方法是必要的。依据偏好聚合的数学形式,社会选择理论为集体决策方法定义的形式理性条件及验证手段,则可转化为检验法律权衡方法的形式理性与方法论效用的一般性方案。作为试验,该方案被运用至阿列克西提出的法律权衡方法“权重公式”,发现了权重公式在形式理性上的重要特征与方法论局限。

An important inquiry of legal balancing theory is about the way in which the methodological effectiveness of a balancing method can be assessed generally without case-by-case verification.A solution from the viewpoint of formal rationality can be found in the‘preference aggregation’model used by social choice theory for studying collective decision-making.Case studies show that legal balancing and collective decision-making share the mathematical form of preference aggregation.They both operate as transitions from plural individual preferences to a single overall preference.With this connection,the analyses of paradoxes in social choice theory reveal the necessity of formal rationality to legal balancing.Based on the mathematical form of preference aggregation,the definition and examination by social choice theorists on the formal rationality of collective decision-making can also be transformed to a general scheme for verifying the formal rationality and methodological effectiveness of legal balancing methods.As a pilot example,the scheme is applied to Alexy’s‘weight formula’and helps to discover the weight formula’s characteristics regarding formal rationality as well as its methodological deficiency.