This paper discusses the “positivistic” idea of the limits of law in various contexts: the conceptual problem of the “limits of law”, the limits of legal interpretation and the limits of theoretical disagreements in jurisprudence. In the latter case, we briefly show how contemporary “reflective” or “critical” positivist theories approach the possibility and limits of disagreements over the “grounds” of law. In what follows, we argue that these theories, which argue for a form of an “institutional” limit for admissible “legal” reasons as built upon theories of basic concepts or normative theories of interpretation, are themselves actually underdetermined by “legal culture” or, so to speak, a “folk theory of law”. In the final section, we outline how a folk theory of law constrains both conceptual and interpretive enterprises in jurisprudence.