A new paper forthcoming in Ethical Norms, Legal Norms:  New Essays in Meteaethics and Jurisprudence (edited by Plunkett, Shapiro & Toh for OUP); the abstract:

In "Explaining Theoretical Disagreement" (2009), I defended an answer to Dworkin's argument that legal positivists can not adequately explain disagreements among judges about what the criteria of legal validity are. I here respond to a variety of critics of my answer, in particular, Kevin Toh. I argue that Toh misrepresents Hart's own views, and misunderstands the role of "presupposition" in both Hart and Kelsen. I argue that a correct reading of Hart is compatible with the error-theoretic interpretation of theoretical disagreement I defended in 2009.