This chapter presents the master argument for medical nihilism. In addition to drawing on the arguments from previous chapters, it introduces three widespread empirical phenomena to support the master argument. First, the ubiquity of medical interventions that have been rejected because they came to be seen as ineffective or harmful. Second, for many of our most widely used medical interventions, the best evidence available indicates that such interventions are barely effective, if at all. Third, the ubiquity of discordance: for many medical interventions, some evidence suggests that they are effective while other evidence suggests that they are not. These empirical phenomena, together with the principled arguments about medical science from earlier chapters, warrant medical nihilism. A formalization of the master argument is offered, which brings together the various arguments from throughout the book. The chapter ends by considering some predictable objections.