The medieval literature of pastoral and spiritual conversion frequently takes a conversational or dialogic form. However, “debate” seems a more apt term for the argumentative and combative dialogues of the two later medieval English pastoral and spiritual texts under scrutiny here: Piers Plowman and Dives and Pauper. These texts are part of a large body of formally self-aware later Middle English dialogue and debate literature, which a number of recent readers have seen as reflecting a newly devotionally keen, theologically well-informed and sometimes assertive laity. In this essay, however, I will argue that the use of debate in Piers Plowman and Dives and Pauper is also a response to a much more long-standing challenge faced by the practitioners of pastoral care: the social and psychological variety of those for whom they have responsibility – “lay multiplicity.” What is particularly striking about these two texts, moreover, is that while they both use debate as a method of dealing with the unpredictable and various reactions of the laity, they do so in very different ways.