Deontic modality: Linguistic and Logical Perspectives on Oughts and Ends

Cleo Condoravdi and Leendert van der Torre

  • Area: LaLo
  • Level: A
  • Week: 2
  • Time: 14:00 – 15:30
  • Room: C2.06


The aim of the course is to enable dialogue between practitioners of logical and linguistic approaches to deontic modality. We examine the semantics of conditional ought broadly construed, including normative, teleological, bouletic, deliberative and advice modals. We present the basic issues raised by modalities and the principal linguistic and logical approaches to them, highlighting their conceptual similarities and differences. Each day of the course presents a new development in deontic logic that features in current debates: practical reasoning (such as means-end reasoning), norm and obligation dynamics, detachment, and multi-agent interaction (as used to model advice uses). All these four challenges are illustrated and analyzed as part of an in-depth discussion of a single problem: the formalization of anankastic conditionals.

  1. Monday: History of deontic logic as a debate between classical vs. alternative semantics. Anankastic conditionals as a central challenge for deontic reasoning.
  2. Tuesday: Kratzer framework for natural language modality, and its relation to Poole default logic. Practical reasoning, in particular means-end reasoning.
  3. Wednesday: Norm change. The AGM framework of theory change. Anankastics as norm change in the Kratzer framework.
  4. Thursday: Endorsement, conditional imperatives, objective versus subjective oughts.
  5. Friday: Pragmatics, advice and other scenarios. Wrap up and outlook.

Slides and handouts

Lecture 1 DSDL

Lecture 1 intro anankastics

Lecture 2 Kratzer means-end

Lecture 2 Poole

Additional References

  1. H. Prakken, M. Sergot 1996: Contrary-to-Duty Obligations. Studia Logica 57(1): 91-115.
  2. K.J. Sæbø 2001: Necessary conditions in a natural language. In: Audiatur Vox Sapientiae: A Festschrift for Arnim von Stechow. Akademie-Verlag, 427–449.
  3. A. Kratzer 1981. The notional category of modality. In: Words, worlds and contexts. De Gruyter, 38-74.
  4. D. Poole 1988. A Logical Framework for Default Reasoning. Artif. Intell. 36(1): 27-47
  5. S. O. Hansson 1993. Reversing the Levi identity. J. Philosophical Logic 22(6): 637-669.
  6. A. von Stechow, S. Krasikova and D. Penka. 2006. Anankastic conditionals again. In A Festschrift for Kjell Johan Sæbø. Forfatterne, 151–171.
  7. C. Condoravdi and S. Lauer. 2016. Anankastic conditionals are just conditionals. Semantics and Pragmatics 9(8).