Abductive conditionals as a test case for inferentialism.

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 has found support for inferentialism, but the materials used concerned a fairly abstract context, leaving open the question of how accurately the account can predict semantic judgments about more realistic materials. To address this question, we conducted three experiments using abductive conditionals, which are conditionals featuring an explanatory-inferential connection between their 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 the inferential connection between antecedent and consequent is. 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 salient 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 co-depend on the strength of the inferential connection between the component parts 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 suppositional account of conditionals as well as with accounts that postulate a more complex probabilistic connection between a conditional's antecedent and consequent. To preview our results, we find strong support for inferentialism across the three experiments.