In this paper, we investigate the ‘ought implies can’ thesis, focusing on explanations and interpretations of OIC, with a view to clarifying its uses and relevance to legal philosophy. We first review various issues concerning the semantics and pragmatics of OIC; then we consider how OIC may be incorporated in Hartian and Kelsenian theories of the law. Along the way we also propose a taxonomy of OIC-related claims.

The two dogmas at issue are the Humean dogma that “‘is’ statements do not imply ‘ought’ statements” and the Kantian dogma that “‘ought’ statements imply ‘can’” statements. The extant literature concludes these logically contradict each other. On the contrary, it is argued here that while there is no derivable formal contradiction, the juxtaposition of the dogmas manifests a philosophical disagreement over how to understand the logic of prescriptions. This disagreement bears on how to understand current metaethical debate between realists and (...) non-realists about morality in a way not heretofore investigated. The conclusion is that realists have the resources to account for both dogmas, while non-realists, if they strictly adhere to the “is”/“ought” gap, cannot give an adequate account of why “ought” implies “can”. (shrink)