Counterfactuals and Undefinedness: Homogeneity vs. Supervaluations

Abstract

Theories of counterfactuals agree on appealing to a relation of comparative similarity, but disagree on the quantificational force of counterfactuals. We report on two experiments testing the predictions of three main approaches: universal theories, homogeneity theories, and single-world selection theories (plus supervaluations over selection functions). The critical cases in our experiment were constructed so as to discriminate between the three theories. Our results provide empirical support for the selectional theories, while challenging the other two approaches.