Abstract

Discussions about the meaning of the word “ought” are pulled in two apparently competing directions. First, in ethical theory this word is used in the paradigmatic statement of ethical principles and conclusions about what some agent is obligated to do. This leads some ethical theorists to claim that the word “ought” describes a real relation, roughly, of being obligated to (realism) or expresses some non-cognitive attitude toward agents acting in certain ways (expressivism). Second, in theoretical linguistics this word is classified as a modal auxiliary verb alongside words like “might,” “may,” “can,” “must,” etc. This leads some theoretical linguists to claim that the word “ought” is a weak necessity modal, which can be modeled with universal quantification over a restricted set of possible worlds. This chapter seeks some resolution of this tension by showing how versions of realism and expressivism can be modified in light of the best semantics of “ought” as a weak necessity modal. In addition, the chapter explains how this semantics might point to a third view—inferentialism—that accounts for the meaning of “ought” not in terms of what relation it describes, nor in terms of what attitude it expresses, but rather in terms of its inferential role.