Reason-Based Logic:
a logic for reasoning with rules and reasons

Jaap Hage and Bart Verheij


The main claim of this paper is that reasoning with rules, especially rules of law, is different from reasoning with statements that are true or false. This difference is, amongst others, reflected in the defeasibility of arguments in which rules play a role. Reason-Based Logic is a logic that has special facilities for dealing with rules and with reasons based on rules. In particular it allows arguments in which conclusions are derived by 'weighing' the reasons that plead for and against them. In this article we illustrate some characteristics of reasoning with rules, and show how Reason-Based Logic deals with these characteristics. The article is concluded with some general considerations concerning Reason-Based Logic, and a comparison with some other logics for defeasible reasoning.

Hage, Jaap and Verheij, Bart (1994). Reason-based Logic: a logic for reasoning with rules and reasons. Law, Computers and Artificial Intelligence, Vol. 3, No. 2/3, pp. 171-209. Also published as report SKBS/B3.A/94-10.

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