Prominent analytical jurisprudents assert that a theory of law consists of necessary, universal truths about the nature of law. This often-repeated claim, which has not been systematically established, is critically examined in this essay. I begin with the distinction between natural kinds and social artifacts, drawing on the philosophy of society to show that necessity claims about law require a fundamental reworking of basic understandings of ontology and epistemology, which legal philosophers have not undertaken. I show law is a poor (...) fit for a priori and a posteriori knowledge. I distinguish between universal application and universal truth, showing the former is sound while the latter is not. I expose the implications that follow from the initial selection of the central case of law, demonstrating that this choice must be justified, and I reveal two ways analytical jurisprudents shield their theories of law from refutation. This analysis raises significant doubts about the claim by analytical jurisprudents that they are identifying necessary, universal truths about the nature of law. (shrink)