Contemporary argumentation theory has developed an impressive array of norms, goals and virtues applicable to ideal argument. But what is the moral status of these prescriptions? Is an interlocutor who fails to live up to these norms guilty of a moral failing as well as an epistemic or cognitive error? If so, why? In answering these questions, I argue that deliberation’s epistemic and cognitive goods attach to important ethical goods, and that respect for others’ rationality, the ethics of joint action, and the importance of consensus join forces with these goods to provide strong reasons for cleaving to high standards of argument. I sketch an illustrative continuum of argument practices of different deliberative-cum-ethical standards, and consider how one should ethically respond when faced with an interlocutor employing less than ideal standards.