Some natural languages do not lexically distinguish between modals of possibility and modals of necessity. From the perspective of languages like English, modals in such languages appear to do double duty: they are used both where possibility modals are expected and where necessity modals are expected. The Nez Perce modal suffix o’qa offers an example of this behavior. I offer a simple account of the flexibility of the o’qa modal centered on the absence of scalar implicatures. O’qa is a possibility modal that does not belong to a Horn scale; its use is never associated with a scalar implicature. Accordingly, in an upward entailing environment, φ-o’qa is appropriate whenever there are accessible φ-worlds, even if indeed all accessible worlds are φ-worlds. In a downward entailing environment, the flexibility of the o’qa modal is seen no more. Here, neither o’qa nor English possibility modals are associated with scalar implicatures, and the use of o’qa exactly parallels the use of English modals of possibility.
Given that o’qa is a possibility modal that does not contrast with a modal of necessity, just how do you talk about necessities in Nez Perce? Speakers translating into Nez Perce rely on a variety of techniques to paraphrase expressions of simple necessity away. Their strategies highlight an area where Nez Perce and English plausibly differ in the range of propositions they convey. The data cast doubt on any strong form of effability as a language universal.