The Logic of Conceivability

Talk by Igor Douven (CNRS, Paris)

Igor Douven on abductive conditionals and Inferentialism: LoC seminar: Wed, April 24, 2019, 16.30-18.00 at the ILLC.

Location: F3.20, ILLC
Time: 16.30-18.00
Title: Abductive Conditionals as a Test Case for Inferentialism

Abstract: According to Inferentialism, for an indicative conditional to be true, there must be a sufficiently strong inferential connection between its antecedent and its consequent. Previous experimental research found support for Inferentialism, but the materials concerned a fairly abstract context, leaving open the question how accurately the account can predict semantic judgments about more realistic materials. To address this question, we use abductive conditionals, in which there is an explanatory-inferential connection between antecedent and consequent (typically, the event cited in the consequent is or purports to be the best explanation of the event cited in the antecedent). Two experiments try to predict truth ratings for such conditionals on the basis of judgments of explanatory goodness. Inferentialism predicts about our materials that participants will tend to agree more with a conditional the better the consequent explains the antecedent and so the stronger is the inferential connection between antecedent and consequent. The first two experiments allow us to contrast Inferentialism with a version of the mental models account that aims to explain truth ratings in terms of accessible alternatives and disablers. A third experiment looks at abductive conditionals in the context of Modus Ponens arguments. Inferentialism predicts that endorsement rates for such arguments depend on the strength of the inferential connection between the antecedent and consequent of the major premise and so, again given our materials, on how well that premise's consequent explains its antecedent. The experiment aims to determine whether there is any support for this prediction, and it also contrasts Inferentialism with the currently dominant Bayesian approach to conditionals. We find unequivocal support for Inferentialism across the experiments, and also find that Inferentialism yields more accurate predictions than the mental models account as well as the Bayesian account.

This is joint work with Patricia Mirabile.