Ronald Dworkin’s contributions to legal philosophy have been subject to severe criticism in recent years. Other legal philosophers call his arguments “deflected or discredited,” laced with “philosophical confusions,” and “deeply embedded” mistakes. As Brian Leiter writes, “[t]he only good news in the story about Dworkin’s impact on law and philosophy is that most of the field declined to follow the Dworkinian path . . . .”

This Article endeavors to show that, far from an effort beset with primitive errors, Dworkin’s challenge to legal positivism in the opening pages of his seminal work was neither misguided nor trivial. Rather, Dworkin’s challenge remains as important and thought-provoking today as it was when he first set it down. His challenge, though straightforward, has never been satisfactorily answered. Rather than grapple with Dworkin’s argument, legal philosophers have either misunderstood or trivialized his insights in the decades since. But there is a reason H.L.A. Hart, one of Dworkin’s examiners at Oxford, saved his jurisprudence examination before ever having reason to believe that Dworkin would become the primary opponent to legal positivism. Hart’s challenge—the argument from theoretical disagreement—still burns bright nearly a quarter-century on.

Furthermore, this Article seeks to explain why legal positivism’s inability to preserve the face value of theoretical disagreement makes it improbable that legal positivism offers an adequate descriptive account of the nature of law. It also endeavors to outline why this deficiency is so immensely important. To accept the legitimacy of theoretical disagreement is accept that to know what the law is one must know something about the moral and political culture in which that law resides.