Reasoning with Inconsistent Information

Abstract

This chapter is devoted to a logical analysis of reasoning with inconsistent information. For legal philosophy and AI-and-law this subject very relevant since, as noted in Chapter 3, the information with which a lawyer is confronted is often contradictory. However, the relevance of this chapter is not restricted to the legal domain; in other domains of common-sense reasoning people are also often confronted with conflicting sources of information. The problem faced by a logical analysis is that according to classical logic inconsistent premises are of no use at all, since classically from a contradiction everything can be derived. Therefore, standard logic is, if not inappropriate, at least insufficient to model nontrivial reasoning with inconsistent information.