ESLLLI Course : Beyond “knowing that”: non-standard epistemic logic

Lecturer: Yanjing Wang (王彦晶)

2nd week, 17:00-18:00

Room: 52.119


Standard epistemic logic focuses on propositional knowledge (in terms of “knowing that“). However, various forms of knowledge are used in everyday life, which suggest non-standard but interesting new epistemic operators. In this course, I survey the recent line of work on modal logics based on “knowing whether", “knowing what" and \knowing how" operators. These new logics are not normal modal logics due to the lack of standard modal axioms, which require new techniques to handle. I will focus on the axiomatizations of such epistemic logics but will also cover issues such as decidability, definability and technical/philosophical comparisons between them and the standard epistemic logic.

Lecture 1: Standard epistemic logic and motivation (

Main Ref (besides the “usual suspects”):

  • Ren-June Wang: Timed Modal Epistemic Logic. PhD thesis (Ch.2&3 about the history of EL), City University of New York (2011)
  • Hintikka, J., Hintikka, M.: Reasoning about knowledge in philosophy: The paradigm of epistemic logic. In: The Logic of Epistemology and the Epistemology of Logic. Volume 200 of Synthese Library. Springer Netherlands (1989) 17–35
Other pointers:
About formal semantics and logic of questions (surveys):
  • D. Harrah: The logic of questions, Handbook of Philosophical Logic, Second Edition (D. Gabbay and F. Guenthner, eds.), vol. 8, Kluwer, Dordrecht/Boston/London, 2002, pp. 1–60.
  • A. Wiśniewski: Semantics of questions, Handbook of Contemporary Semantics. Second Edition (S. Lappin and C. Fox, eds.), Wiley-Blackwell, 2014.
About embedded question, factivity:
  • P. ‎Egré: Question-embedding and factivity. Grazer Philosophische Studien 77(1) (2008) 85– 125
About DEL in terms of intuitive ETL-like axioms without reductions:
About Techniques and philosophy of Quantified modal (epistemic) logics:
  • Fitting, M., First-order intensional logic, Annals of Pure and Applied Logic 127 (2004), pp. 171-193.
  • Holliday, Wesley H. & Perry, John (2014). Roles, Rigidity, and Quantification in Epistemic Logic. In Alexandru Baltag & Sonja Smets (eds.), Trends in Logic, Outstanding Contributions: Johan van Benthem on Logic and Information Dynamics. Springer 591-629.
  • F. Belardinelli, A. Lomuscio, Quantified epistemic logics for reasoning about knowledge in multi-agent systems, Artificial Intelligence, Volume 173, Issues 9–10, June 2009, Pages 982-1013.
  • G. Corsi, E. Orlandelli: Free Quantified Epistemic Logics. Studia Logica 101(6): 1159-1183 (2013)
About simulating neighborhood semantics using Kripke semantics:
  • Kracht, M., Wolter, F.: Simulation and transfer results in modal logic - A survey. Studia Logica 59(1) (1997) 149–177
About concealed questions:
  • Maria Aloni and Floris Roelofsen. Interpreting Concealed Questions Linguistics and Philosophy 34(5), 443-478, 2011
  • Maria Aloni. Quantification under Conceptual Covers. PhD thesis University of Amsterdam, Amsterdam, 2001.

Lecture 2: Logics of “knowing whether” (

Main Ref:

Other pointers:
  • Ciardelli, I., Roelofsen, F.: Inquisitive dynamic epistemic logic. Synthese 192(6) (2015) 1643– 1687
  • M. Aloni, P. Égré, Tikitu de Jager: Knowing whether A or B. Synthese 190(14): 2595-2621 (2013)

Lecture 3: Logics of “knowing what” (

Main Ref:
  • About knowing value and knowing whether in AI (epistemic) planning:

Lecture 4: Logics of “knowing how” (

Main Ref

Lecture 5: Future work (slides)