Portner & Rubinstein (2014) offer a compelling account of gradable modal expressions (e.g. important) that folds together a Kratzerian approach to modality (Kratzer 1981) with a degree-semantic theory of gradable adjectives. In this talk, I will show that Portner & Rubinstein's theory has two notable problems: a) it predicts rampant incommensurability effects where they do not occur, and b) as they themselves observe, it cannot readily handle cases of equally important but incompatible goals, such as (1).
I propose an analysis of gradable modality that resolves these issues while retaining the conservative Kratzerian sensibilities of Portner & Rubinstein's analysis. This is accomplished by adding a degree argument to the ordering source, making it a context-sensitive function from worlds and degrees to sets of propositions. At each degree-level, the ordering source orders worlds just like in Kratzer's theory. However, a mechanism is built into gradable modals that allows orderings from higher degrees to "trickle down" to lower degrees, in a fashion similar to von Fintel & Iatridou's (2008) treatment of weak necessity modals. The flexibility afforded by this approach avoids predicting such fine-grained incommensurability effects as Portner & Rubinstein's theory; it also permits an analysis of (1), since nothing prevents the ordering source from being different for preserve the wetlands (e.g. in view of environmental priorities) and build the new housing (e.g. in view of financial concerns).