David Plunkett

In “How Facts Make Law” and other recent work, Mark Greenberg argues that legal positivists cannot develop a viable constitutive account of law that meets what he calls the “the rational-relation requirement.” He argues that this gives us reason to reject positivism in favor of antipositivism. In this paper, I argue that Greenberg is wrong: positivists can in fact develop a viable constitutive account of law that meets the rational-relation requirement. I make this argument in two stages. First, I offer an account of the rational-relation requirement. Second, I put forward a viable positivist account of law that I argue meets this requirement. The account that I propose is a version of Scott Shapiro’s Planning Theory of Law. The version of Shapiro’s account that I propose combines (1) the account of concepts and conceptual analysis put forward by David Chalmers and Frank Jackson with (2) the account of the concept LEGAL INSTITUTION (and its conceptual connections to the concept LEGAL NORM) that we get from a certain reading of Shapiro’s Planning Theory. In addition to providing a compelling response to Greenberg’s argument in “How Facts Make Law,” I argue that the explanation for why my response to Greenberg works underscores one of the central problems facing legal antipositivism: namely, its lack of a convincing account of the nature of legal institutions.