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Reducing Contrastive Knowledge

  • Michael CohenEmail author
Original Research


According to one form of epistemic contrastivism, due to Jonathan Schaffer, knowledge is not a binary relation between an agent and a proposition, but a ternary relation between an agent, a proposition, and a context-basing question. In a slogan: to know is to know the answer to a question. I argue, first, that Schaffer-style epistemic contrastivism can be semantically represented in inquisitive dynamic epistemic logic, a recent implementation of inquisitive semantics in the framework of dynamic epistemic logic; second, that within inquisitive dynamic epistemic logic, the contrastive ternary knowledge operator is reducible to the standard binary one. The reduction shows, I argue, that Schaffer’s argument in favor of contrastivism is compatible with a binary picture of knowledge. This undercuts the force of the argument in favor of contrastivism.



I would like to thank Johan van Benthem, Ray Briggs, Ivano Ciardelli, Krista Lawlor, Lisa Modifica, Jonathan Schaffer and and two anonymous referees of this journal for many helpful comments, suggestions and corrections on earlier versions of this article.


  1. Aloni, M., & Egre, P. (2008). Alternative questions and knowledge attributions. Philosophical Quarterly, 60, 1–27.CrossRefGoogle Scholar
  2. Aloni, M., Égré, P., & de Jager, T. (2013). Knowing whether A or B. Synthese, 190(14), 2595–2621.CrossRefGoogle Scholar
  3. Baltag, A., & Renne, B. (2016). Dynamic epistemic logic. In E. N. Zalta (Ed.), The Stanford encyclopedia of philosophy. Winter 2016 edition.Google Scholar
  4. Ciardelli, I. (2016). Questions in logic. Ph.D. Thesis, University of Amsterdam.Google Scholar
  5. Ciardelli, I., Groenendijk, J., & Roelofsen, F. (2018). Inquisitive semantics. In Oxford surveys in semantics and pragmatics. Oxford: Oxford University Press.Google Scholar
  6. Ciardelli, I., & Roelofsen, F. (2015). Inquisitive dynamic epistemic logic. Synthese, 192(6), 1643–1687.CrossRefGoogle Scholar
  7. Cross, C., & Roelofsen, F. (2016). Questions. In E. N. Zalta (Ed.), The Stanford encyclopedia of philosophy. Spring 2016 edition.Google Scholar
  8. Dretske, F. I. (1972). Contrastive statements. Philosophical Review, 81(4), 411–437.CrossRefGoogle Scholar
  9. Gerken, M. (2013). Epistemic focal bias. Australasian Journal of Philosophy, 91(1), 41–61.CrossRefGoogle Scholar
  10. Groenendijk, J. (2007). The dynamics of inquiry. In Central APA. Handout.Google Scholar
  11. Hawke, P. (2016). Questions, topics and restricted closure. Philosophical Studies, 173(10), 2759–2784.CrossRefGoogle Scholar
  12. Hintikka, J. (1975). Different constructions in terms of the basic epistemological verbs: A survey of some problems and proposals. In The intensions of intentionality and other new models for modalities (pp. 1–25). Dordrecht: D. Reidel.CrossRefGoogle Scholar
  13. Karjalainen, A., & Morton, A. (2003). Contrastive knowledge. Philosophical Explorations, 6(2), 74–89.CrossRefGoogle Scholar
  14. Lewis, D. (1982). Whether’ report. In T. Pauli (Ed.), 320311: Philosophical essays dedicated to Lennart Åqvist on his fiftieth birthday (pp. 194–206). Uppsala: University of Uppsala Press.Google Scholar
  15. Roelofsen, F. (2015). The semantics of declarative and interrogative lists. Manuscript, ILLC University of Amsterdam.Google Scholar
  16. Rysiew, P. (2011). Epistemic contextualism. In E. N. Zalta (Ed.), The Stanford encyclopedia of philosophy. Winter 2011 edition.Google Scholar
  17. Schaffer, J. (2004). From contextualism to contrastivism. Philosophical Studies, 119(1–2), 73–104.CrossRefGoogle Scholar
  18. Schaffer, J. (2005). Contrastive knowledge. In T. S. Gendler & J. Hawthorne (Eds.), Oxford studies in epistemology (Vol. 1, p. 235). Oxford: Oxford University Press.Google Scholar
  19. Schaffer, J. (2007a). Closure, contrast, and answer. Philosophical Studies, 133(2), 233–255.CrossRefGoogle Scholar
  20. Schaffer, J. (2007b). Knowing the answer. Philosophy and Phenomenological Research, 75, 383–403.CrossRefGoogle Scholar
  21. Schaffer, J. (2008). The contrast-sensitivity of knowledge ascriptions. Social Epistemology, 22(3), 235–245.CrossRefGoogle Scholar
  22. Schaffer, J., & Knobe, J. (2012). Contrastive knowledge surveyed. Nous, 46(4), 675–708.CrossRefGoogle Scholar
  23. Schaffer, J., & Szabó, Z. G. (2014). Epistemic comparativism: A contextualist semantics for knowledge ascriptions. Philosophical Studies, 168(2), 491–543.CrossRefGoogle Scholar
  24. Stanley, J. (2011). Know how. Oxford: Oxford University Press.CrossRefGoogle Scholar
  25. van Benthem, J., & Minică, Ş. (2009). Toward a dynamic logic of questions. In X. He, J. Horty, & E. Pacuit (Eds.), Logic, rationality, and interaction (pp. 27–41). Berlin: Springer.CrossRefGoogle Scholar
  26. van Ditmarsch, H., van der Hoek, W., & Kooi, B. (2007). Dynamic epistemic logic. In Synthese library. Netherlands: Springer.Google Scholar
  27. van Gessel, T. (2018). Action models in inquisitive logic. Synthese.

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© Springer Nature B.V. 2019

Authors and Affiliations

  1. 1.Stanford UniversityStanfordUSA

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