Johnson builds on the idea that agents, at least sometimes, have an epistemic obligation to voice disagreements. Any of four background theories, inspired by influential work in social epistemology, can generate these obligations. However, each background theory generates obligations with different characteristics. Johnson explores these differences by looking at the extent and limits of each. Key questions include the conditions under which agents should voice their disagreement, and to what extent that disagreement must be sincere. One way of asking this second question is to ask, to what extent are we epistemically obligated to play devil’s advocate?