One of Mill’s primary targets, throughout his work, is intuitionism. In this paper, I distinguish two strands of intuitionism, against which Mill offers separate arguments. The first strand, ‘a priorism’ makes an epistemic claim about how we come to know norms. The second strand, ‘first principle pluralism’, makes a structural claim about how many fundamental norms there are. In this paper, I suggest that one natural reading of Mill’s argument against first principle pluralism is incompatible with the naturalism that drives his argument against a priorism. It must, therefore, be discarded. Such a reading, however, covertly attributes Mill realist commitments about the normative. These commitments are unnecessary. To the extent that Mill’s argument against first principle pluralism is taken seriously, I suggest, it is an argument that points towards Mill as having an antirealist approach to the normative.