Counterfactuals and Undefinedness: Homogeneity vs. Supervaluations

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