An Epistemic Step for Anti-Presuppositions

Sentence (1) strongly suggests that the speaker does not have a sister: (1) John believes that I have a sister. a. Alternative: John knows that I have a sister. b. Actual inference: the speaker does not have a sister. 5 c. Predicted inference: it is not common belief that the speaker has a sister. According to Heim (1991), Percus (2006), and Sauerland (2006), this inference should follow from the comparison of (1) to (1a). However, such an analysis would only predict a very weak implicature: it is not common belief that the speaker has a sister. I propose to strengthen this prediction by two means. First, I rely on a precise 10 understanding of the modern Stalnakerian view of presuppositions and common ground (Stalnaker, 1998, 2002; von Fintel, 2000; Schlenker, 2006). Second, I argue that this inference depends on contextual factors. More precisely, I show that the Competence Assumption (see Spector, 2003, van Rooij and Schulz, 2004, and Sauerland, 2004) necessary to obtain secondary scalar implicatures should be supplemented with an 15 Authority Assumption. I motivate this additional assumption on independent empirical grounds. Finally, I show how my proposal accounts for a wide variety of inferences with fine variations governed by (i) contextual differences and (ii) specific properties of the presupposition triggers involved.