Remarks on counterpossibles

Authors: Berit Brogaard Joe Salerno

Publish Date: 2012/12/21

Volume: 190, Issue: 4, Pages: 639-660

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Abstract

Since the publication of David Lewis’ Counterfactuals the standard line on subjunctive conditionals with impossible antecedents or counterpossibles has been that they are vacuously true That is a conditional of the form ‘If p were the case q would be the case’ is trivially true whenever the antecedent p is impossible The primary justification is that Lewis’ semantics best approximates the English subjunctive conditional and that a vacuous treatment of counterpossibles is a consequence of that very elegant theory Another justification derives from the classical lore than if an impossibility were true then anything goes In this paper we defend nonvacuism the view that counterpossibles are sometimes nonvacuously true and sometimes nonvacuously false We do so while retaining a Lewisian semantics which is to say the approach we favor does not require us to abandon classical logic or a similarity semantics It does however require us to countenance impossible worlds An impossible worlds treatment of counterpossibles is suggested but not defended by Lewis Counterfactuals Blackwell Oxford 1973 and developed by Nolan Notre Dame J Formal Logic 38325–527 1997 Kment Mind 115261–310 2006a Philos Perspect 20237–302 2006b and Vander Laan In Jackson F Priest G eds Lewisian themes Oxford University Press Oxford 2004 We follow this tradition and develop an account of comparative similarity for impossible worlds

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