Weak Necessity

Getting the meaning of ought right and accounting for its relation to must has proven to be a considerable challenge for deontic logic as well as formal semantic analyses of modality. This chapter aims to give a language-independent characterization of weak necessity as a phenomenon of gradable modality, focusing on morphological, semantic, and discursive properties of modals like ought. Weak necessity requires us to distinguish between degrees of necessity. Two theoretical frameworks for doing so are evaluated in the chapter. The two frameworks are shown to have complementary strengths, highlighting the distinction between probability-based weak necessities and priority-oriented ones.