A logic for the natural language conditional

Abstract

Ordinary speakers intuitively assign truth-values to conditional utterances in everyday conversation, but, despite the general ease with which this occurs, it is notoriously difficult to give an account of the implicit logic that is followed in making these truth-value assignments. I propose a twofold logic of the conditional – a relatively simple “factual” logic for conditionals interpreted with regard to what is actually the case, largely following the logic of the material conditional; combined with a variably strict possible-worlds counterfactual logic for conditionals interpreted with regard to with what may be (or may have been) the case, incorporating a ceteris paribus clause. This theory is able to deal with a number of challenges for other prominent views of the conditional, such as counter-intuitive truth-value ascriptions provided by notions of similarity or closeness, and difficulties adequately accounting for phenomena such as reverse Sobel sequences.