Our paper “Fixing de Morgan’s law in counterfactual antecedents” is now available as part of the Proceedings of the 22nd Amsterdam Colloquium here!
Abstract:
Classical semantics for counterfactuals are based on a notion of comparative similarity.
These semantics are intensional, hence they predict that logically equivalent clauses can
be substituted in counterfactuals salva veritate. A recent truth-value judgment study by
Ciardelli, Zhang, and Champollion ([6]; CZC) appears to challenge both the idea that comparative similarity plays a role in counterfactual semantics and the prediction that logical
equivalents are substitutable. CZC account for their data via an inquisitive semantics for
disjunction and a semantics for counterfactuals that does not exploit the standard similarity algorithm. We report on a study consisting of two experiments that start from CZC’s
general idea, but use a simpler scenario, manipulate negation more systematically, and add
an extra task based on the selection of pictures. Our results replicate the differences found
by CZC, but they also suggest that the effect is linked to the presence of overt negation
rather than disjunction. We conclude that (i) inquisitive disjunction is neither necessary
nor sufficient to account for the problem in full generality, and (ii) the evidence does not
encourage rejecting a similarity semantics.