Abstract Suppose that we believe that a concept is irreducible. Suppose further a challenger claims that the concept is unintelligible or incoherent. How do we demonstrate that the concept is intelligible given that the irreducible concept cannot be further broken down? I show how to explain an irreducible concept in order to meet Anscombe’s accusation that the deontic concepts in ethics are nonsense without a belief in God as lawgiver. To meet Anscombe’s challenge, I turn to the work of the British intuitionists. Their ‘structural explanations’ of the deontic concepts are relevant to refuting Anscombe because they demonstrate that we already do coherently grasp the deontic concepts without God. They do this by making perspicuous what is implicit when we use the concepts. As Parfit said, we must ‘explain such concepts in a different way, by getting people to think thoughts that use these concepts.’
Andrew Ingram (Wed,) studied this question.