Ecole Normale Supérieure
May 29, 2009
45 rue d'Ulm - Paris
Salle des Actes

Workshop description

Various connections exist between decision theory and the topic of vagueness. Preferences can be vague or fuzzy, for instance when agents do not perfectly discriminate between their options. The indifference relation is then typically non-transitive, contrary to standard assumptions on rationality. One aspect of the workshop will be the discussion of non-transitive structures used in decision-theory (such as semi-orders and their generalizations, see Luce), and their correspondence with models of vagueness put forward in the philosophical literature to model the notions of similarity and imperfect indiscriminability (Goodman, Williamson). Other connections between decision and vagueness will be discussed, such as the use of choice functions to deal with comparison and semantic vagueness, the role of decision for the resolution of vagueness in communication, or the articulation between decision and perception in psychological models of discrimination based on decision theory (such as signal detection theory). The aim of the workshop is to promote dialogue between philosophers, economists and linguists interested in these issues.


  • Mikaël Cozic (Institut Jean Nicod)
  • Paul Egré (Institut Jean-Nicod)
  • Leon Horsten (Bristol University)
  • Kris de Jaegher (Utrecht)
  • Robert van Rooij (ILLC, Amsterdam)
  • Maurice Salles (Université de Caen)
Richard Dietz (Leuven/Arché)
David Etlin (Tufts)

Organization & Contact

  • M. Cozic and P. Egré (IJN).
  • Contact:  mikael.cozic AT