Why Legal Theory is Political Philosophy

This article is part of a symposium issue on Scott Shapiro\u27s book, Legality. It explores the question whether Shapiro\u27s moral aim functionalism about the nature of law brings him into conflict with his own commitment to legal positivism. The article points out the role framing judgments must play in working out moral-aim functionalism. Framing judgments state the necessary conditions of pursuing a moral aim, as contrasted to perhaps simply pretending to. As such, framing judgments determine whether an institution structured as a self-certifying, compulsory, comprehensive planning institution also in fact pursues a moral aim. Determining whether an institution pursues a moral aim, or not, does not require delivering a verdict on its moral worth. But it does require setting out at least the rudiments of a theory of political legitimacy, and a theory of political legitimacy belongs to political philosophy. Thus, in this crucial respect, legal theory is political philosophy. The article also explores the relation between the concept of a legal institution, and the concept of legal content. Drawing upon, but also critiquing, recent work by David Plunkett, the article challenges the widely assumed primacy of the concept of legal institution over that of legal content. If this challenge is successful, it makes trouble for those, like Shapiro, who want to be moral-aim functionalists about the concept of legal institution, while remaining legal positivists about the concept of legal content. If a moral aim certifies an otherwise-qualified institution as legal, it is conceivable that the legality of the norms it generates is to be certified solely by reference to their institutional source. A norm might be a legal norm regardless of any aim it could be said to have in itself. What, then, of customary law? That is, norms that count as legal despite lacking an institutional source? A moral-aim functionalist about legal institutions, who insists on a source-based test of legal content, has either to deny that there are customary laws, strictly speaking, or to face the question: how to distinguish mere custom from customary law? If (by parallel) a moral-aim different aim of customary legal norm is admitted, then the theory is no longer a legal positivism about legal norms