Scott Shapiro builds his case for legal positivism on what we might call the model of plans. The central idea is simple: laws are plans. If you follow Shapiro that far, his defense of legal positivism requires just one more step. The content of a plan, Shapiro says, is fixed by social facts about the adoption and acceptance of the plan. Put those claims together, and legal positivism follows from plan positivism, coupled with the fact that laws are plans.
At least, that’s how Shapiro’s argument goes. I do not think that it works, and my primary aim in this essay is to explain why. I argue that even if we concede that laws are plans, and that the content of a plan is determined by social facts, it does not follow that the content of the law is determined by social facts. If I am right, then Shapiro has not completed his case for legal positivism. But I aim to show more than that Shapiro’s argument for positivism fails. It fails, I argue, in ways that reveal structural problems with a family of prominent positivist views, including the one defended by Joseph Raz. Thus, reflecting on the model of plans can teach us a lot about the prospects for positivism.