Prohairetic Deontic Logic (PDL)

  • Leendert W. N. van der Torre
  • Yao-Hua Tan
Conference paper

DOI: 10.1007/3-540-49545-2_6

Part of the Lecture Notes in Computer Science book series (LNCS, volume 1489)
Cite this paper as:
van der Torre L.W.N., Tan YH. (1998) Prohairetic Deontic Logic (PDL). In: Dix J., del Cerro L.F., Furbach U. (eds) Logics in Artificial Intelligence. JELIA 1998. Lecture Notes in Computer Science, vol 1489. Springer, Berlin, Heidelberg


In this paper we introduce Prohairetic Deontic Logic (PDL), a preference-based dyadic deontic logic. An obligation ‘α should be (done) if β is (done)’ is true if (1) no ¬αβ state is as preferable as an αβ state and (2) the preferred β states are α states. We show that the different elements of this mixed representation solve different problems of deontic logic. The first part of the definition is used to formalize contrary-to-duty reasoning, that for example occurs in Chisholm’s and Forrester’s notorious deontic paradoxes. The second part is used to make dilemmas inconsistent. PDL shares the intuitive semantics of preference-based deontic logics without introducing additional semantic machinery such as bi-ordering semantics or ceteris paribus preferences.


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Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • Leendert W. N. van der Torre
    • 1
  • Yao-Hua Tan
    • 2
  1. 1.IRITPaul Sabatier UniversityToulouseFrance
  2. 2.EuridisErasmus University RotterdamThe Netherlands

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