This episode sets the stage for the next one by drawing and explaining a distinction in epistemic rationality. It argues that rationality is always a structural feature. When inquiry is personal—such as inquiry into matters of taste—this structure is internal to the individual and it is characterized by certain personal nodes, such as aesthetic predilections or fundamental moral convictions, whereas when inquiry is shared—such as scientific inquiry—we aim toward an interpersonal structure that is purely based on shareable evidence and lacks these personal nodes. This difference in rationality sheds light on differences in the mechanics of testimony and peer disagreement that will be very important for explaining why philosophy is a personal inquiry.