How to Embed Epistemic Modals without Violating Modus Tollens


Epistemic modals in consequent place of indicative conditionals give rise to apparent counterexamples to Modus Ponens and Modus Tollens. Familiar assumptions of familiar truth conditional theories of modality facilitate a prima facie explanation—viz., that the target cases harbor epistemic modal equivocations. However, these explanations go too far. For they foster other predictions of equivocation in places where in fact there are no equivocations. It is argued here that the key to the solution is to drop the assumption that modal claims are inherently relational (i.e., that they express a logical relation between a prejacent and a premise-set) in favor of a view that treats them as inherently quantificational. In particular it is suggested that modals are mass noun descriptions of information. We demonstrate how this approach unlocks the equivocation problem. The majority of this paper was written during my time at the Jean Nicod Institute in Paris. Thanks to them for having me and to Saint Louis University for the research leave.

Cite this paper

@inproceedings{Salerno2013HowTE, title={How to Embed Epistemic Modals without Violating Modus Tollens}, author={Joseph T . Salerno}, year={2013} }