Presuppositions project asymmetrically, unless they don’t

Abstract

We present two experiments that shed new light on the old (but ongoing) debate on filtering (a-)symmetries with presuppositions (Karttunen 1974; Heim 1983; Soames 1989; Schlenker 2008 a.o.). The experiments establish that unless and if not exhibit symmetric filtering. In this respect, they pattern together with disjunction, and contrast with conjunction. We end by examining the ramifications of our results for possible theories of presupposition.