Defeasible reasoning in law

摘要

Numerous legal scholars have asserted that legal reasoning is largely a deductive process in which legal rules are applied to the facts of a case in order to derive a conclusion. Though some might contest this assertion, it seems that what we know as law is largely a system of rules. However, these rules are not immutable and fully consistent; in many cases, multiple rules can be applied to the facts of a case, the conclusion derived from one rule conflicting with and potentially defeating that derived from another rule. In this paper, we discuss legal reasoning as defeasible reasoning and present a prototype of a computer-based legal reasoning system to illustrate the advantages of our approach. Defeasible reasoning is an appropriate foundation for the development of legal support systems because it not only can support the non-monotonicity of legal rules but also can resolve many of the conflicts that arise in applying these rules.