, Volume 42, Issue 2, pp 285-315
Date: 08 Feb 2012

An Inconsistency-Adaptive Deontic Logic for Normative Conflicts

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We present the inconsistency-adaptive deontic logic DP r , a nonmonotonic logic for dealing with conflicts between normative statements. On the one hand, this logic does not lead to explosion in view of normative conflicts such as O A ∧ OA, O A ∧ PA or even O A ∧ ∼O A. On the other hand, DP r still verifies all intuitively reliable inferences valid in Standard Deontic Logic (SDL). DP r interprets a given premise set ‘as normally as possible’ with respect to SDL. Whereas some SDL-rules are verified unconditionally by DP r , others are verified conditionally. The latter are applicable unless they rely on formulas that turn out to behave inconsistently in view of the premises. This dynamic process is mirrored by the proof theory of DP r .

We are greatly indebted to Hans Lycke and to the anonymous referees for their valuable comments and suggestions. Research for this paper was supported by subventions from Ghent University and the Research Foundation Flanders (FWO).