On the Meaning of 'Ought'

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 relation, roughly, of being obligated to. 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. Sometimes these views are thought to be complementary. However, in this paper, I use arguments for the second view to raise a novel problem for the first view. The point of this is to show how the dominant approach to the semantics of ordinary language modals in theoretical linguistics should actually be seen as supporting some form of anti-descriptivism in metaethical debate about the meaning of ‘ought’, though no ordinary form of expressivism.