Why ‘Ought’ Detaches: Or, Why You Ought to Get with My Friends (If You Want to Be My Lover)

This paper argues that a standard analysis of modals from formal semantics suggests a solution to the detaching problem — the problem of whether un-embedded 'ought'-claims can "detach" (be derived) from hypothetical imperatives and their antecedent conditions. On a broadly Kratzerian analysis, modals have a skeletal conventional meaning and receive a particular reading (e.g., deontic, epistemic, teleological) only relative to certain forms of contextual supplementation. I argue that 'ought'-claims can detach — subject to an important qualification — but only as long as the 'ought's in the conditional premise and conclusion are interpreted relative to the same ordering sources. Although modus ponens can be shown to fail with hypothetical imperatives, the cases in question do not constitute a failure of detachment in the sense that ethicists have cared about. Rival wide-scoping accounts are proven to be linguistically problematic. They make incorrect predictions about the meanings of hypothetical imperatives, and founder in response to quantificational variants of the detaching problem