Workshop with Timothy Williamson

Date: May 28 2015

The topic is work that is related to conditionals by Timothy Williamson, Wykeham Professor of Logic at Oxford.

We will have guests commenting on his work, his replies, and discussion.

  Speakers:

• Timothy Williamson • Counterpossibles


• Peter Fritz (Oxford) • Counterfactuals and Propositional Contingentism
  Abstract

  Timothy Williamson has argued against the principle of conditional excluded middle (CEM) in counterfactual logic. More recently, he has argued that it is necessary what propositions there are. A formal argument will be presented to show that he can't be wrong on both counts: CEM rules out contingency in what propositions there are. The argument uses an abstract possible world semantics which does not presuppose any particular way of modeling counterfactuals. Crucial assumptions in the argument are a restricted comprehension principle for propositions, which Williamson has argued should be accepted even by those who think that it is contingent what propositions there are, and an infinitary agglomeration principle for counterfactuals which is widely endorsed, even though it is not valid according to David Lewis's semantics for counterfactuals. The argument also essentially relies on a modal formulation of CEM which applies to merely possible propositions. It will be argued that endorsing CEM only for propositions there are is not plausible, as the best arguments for CEM extend to its modal formulation.



• Jeremy Goodman (Oxford) • If I were you
  Abstract

  In The Philosophy of Philosophy Timothy Williamson explores the philosophical significance and modal logic of counterfactual necessity, where a proposition is counterfactually necessary just in case a contradiction would have been true had that proposition been false. In this talk I explore the view that claims of numerical distinctness are not counterfactually necessary. I consider some motivations for this view and then explore some of its implications for the logic of counterfactual necessity. I also respond to an argument of Williamson's for the necessity of distinctness which appeals to certain principles about the logic of actuality. I conclude by considering two implications of the view: one concerning the relation between counterfactual necessity and so called "metaphysical" necessity, and another concerning the role of counterfactual reasoning in philosophical theorizing.