William H Hanson

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I am primarily interested in what follows from what, and why. Hence my specialization in logic and the philosophy of logic. I have worked in areas from inductive to deontic logic, but the concept of necessity and the role it plays in grounding the relation of logical consequence have long been major interests. My work on validity in intensional languages reflects these interests, as does my ongoing investigation of the relations between formally precise and intuitively correct accounts of logical consequence. This latter work grows out of the observation that the informal characterization logicians give of the logical consequence relation does not always square with the almost universally accepted model-theoretical definition of this relation. Issues about the role of necessity, what is to count as a logical constant, the correct way of representing logical form, and the relation of set theory to logic all come into play. A related question I have investigated is whether there can be genuine, as opposed to merely verbal, disputes about which principles of logic are correct. (This is the problem of deviant logics or logical pluralism.) In my paper on deviance I try to show how genuine disagreement about logic could come about. Another matter that interests me is the relation between natural and formal languages. One of my papers explores the logic of English indicative conditionals, while another shows that certain non-trivial fragments of English can be translated into the language of propositional logic in a completely mechanical way.

Educational Background & Specialties

Educational Background

  • Ph.D.: Philosophy, Yale University.


  • logic
  • philosophy of logic
  • philosophy of language
Courses Taught
  • Symbolic Logic
  • Modal Logic
  • Philosophy of Logic
  • Seminars on various topics in Philosophical Logic
Research & Professional Activities

Professional Activities

  • Visiting Professor, University of Graz, Austria, 1992 and 2002:
  • Visiting Professor, University of Salzburg, Austria, 1994:
  • Visiting Professor, University of Munich, Germany, 1999:
  • "The Paradox of NonBeing," Grazer Philosophische Studien, 73 (2006), 205-219.
  • "Actuality, Necessity and Logical Truth," Philosophical Studies, 130 (2006), 437-459.
  • "The Formal-Structural View of Logical Consequence: A Reply to Gila Sher," The Philosophical Review, 111 (2002), 243-258.
  • "Ray on Tarski on Logical Consequence," Journal of Philosophic Logic, 28 (1999), 607-618.
  • "The Concept of Logical Consequence," The Philosophical Review, 106 (1997), 365-409.
  • "Indicative Conditionals Are Truth-Functional," Mind, 100 (1991), 53-72.
  • "Two Kinds of Deviance," History and Philosophy of Logic, 10 (1989), 15-28.
  • "Validity in Intensional Languages: A New Approach," with James Hawthorne, Notre Dame Journal of Formal Logic, 26 (1985), 9-33.
  • "Actualism, Serious Actualism, and Quantified Modal Logic," Notre Dame Journal of Formal Logic, 59 (2018), 233-284.
  • National Endowment for the Humanities Fellowship, 1974 - 1975
  • Visiting Scholar, Center for the Study of Language and Information, Stanford University, 1987
  • Horace T. Morse-Minnesota Alumni Association Award for Outstanding Contributions to Undergraduate Education, 1992
  • Member of Academy of Distinguished Teachers, since 1999