On the Ambiguity of Will -Conditionals

Abstract We bring together two widely accepted ideas: (i) conditionals with modal consequents are systematically ambiguous between a reading on which the if-clause restricts the modal, and a reading on which the if-clause introduces an epistemic supposition and the modal is unrestricted; (ii) ‘will’ is a modal. Together, (i) and (ii) imply that will-conditionals are systematically ambiguous between a reading as restricted historical claims, and one as unrestricted historical claims made under a supposition. We argue that this prediction is borne out and that the existence of the relevant ambiguity has far-reaching repercussions for several important debates concerning conditionals, including: the debate on the relation between past-tense indicatives and counterfactuals; on whether will-conditionals belong with the former or with the latter kind, and more generally, on how conditionals ought to be classified; on the presuppositions of indicative conditionals; on the relation between conditionals and supposition; and on the role of indicative conditionals in deliberation.