Beyond the Separability Thesis: Moral Semantics and the Methodology of Jurisprudence

In emphasizing the importance of the separability thesis, legal philosophers have inadequately appreciated other philosophically important ways in which law and morality are or might be connected with one another. In this article, I argue that the separability thesis cannot shoulder the philosophical burdens that it has been asked to bear. I then turn to two issues of greater importance to jurisprudence. These are ‘the moral semantics of law’ and ‘the normativity of theory construction in jurisprudence’. The moral semantics claim is that legal content is best understood as moral directives about what is to be done and who is to decide what is to be done. The problem is that legal positivists typically hold that only social facts contribute to the content of law, and it is hard to see how a positivist can hold both the social-facts claim and the moral-semantics claim. I argue that not only are the two claims consistent with one another, but that legal positivists must hold some version of the moral semantics claim if they are to make sense of the claim that legal reasons purport to be content-independent moral reasons for acting. In Section 3 of the article, I take up the question of whether theory construction in jurisprudence is normative or descriptive. This is hard to do in part because so little attention has been paid to correctly formulating the issue. I suggest a demanding test for descriptivism; namely, that an adequate analysis of law can be provided entirely in terms of its formal features. I then defend this claim against three arguments designed to show because governance by law is necessarily desirable or valuable that, we cannot characterize law without making reference to those values or to other material features of law. This constitutes a limited but powerful defence of descriptive jurisprudence.