Studia Logica

, Volume 57, Issue 1, pp 73–90

Two approaches to the formalisation of defeasible deontic reasoning

  • Henry Prakken

DOI: 10.1007/BF00370670

Cite this article as:
Prakken, H. Stud Logica (1996) 57: 73. doi:10.1007/BF00370670


This paper compares two ways of formalising defeasible deontic reasoning, both based on the view that the issues of conflicting obligations and moral dilemmas should be dealt with from the perspective of nonmonotonic reasoning. The first way is developing a special nonmonotonic logic for deontic statements. This method turns out to have some limitations, for which reason another approach is recommended, viz. combining an already existing nonmonotonic logic with a deontic logic. As an example of this method the language of Reiter's default logic is extended to include modal expressions, after which the argumentation framework in default logic of [20, 22] is used to give a plausible logical analysis of moral dilemmas and prima facie obligations.

Key words

deontic reasoning defeasible reasoning moral dilemmas 

Copyright information

© Kluwer Academic Publishers 1996

Authors and Affiliations

  • Henry Prakken
    • 1
  1. 1.Computer/Law Institute Faculty of LawFree UniversityHV AmsterdamThe Netherlands

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