Complex probability expressions & higher-order uncertainty: Compositional semantics, probabilistic pragmatics & experimental data.

We present novel experimental data pertaining to the use and interpretation of simple probability expressions (such as possible or likely) and complex ones (such as possibly likely or certainly possible) in situations of higher-order uncertainty, i.e., where speakers may be uncertain about the probability of a chance event. The data is used to critically assess a probabilistic pragmatics model in the vein of Rational Speech Act approaches (e.g., Frank and Goodman, 2012; Franke and Jäger, 2016; Goodman and Frank, 2016). The model embeds a simple compositional threshold-semantics for probability expressions, following recent work in formal linguistics (Swanson, 2006; Yalcin, 2007, 2010; Lassiter, 2010, 2017; Moss, 2015).