Mark Vorobej develops a novel approach to argument interpretation and evaluation that synthesizes subjective concerns about the personal points of view of individual arguers, with objective concerns about the structural properties of arguments. One of the key themes of the book is that we cannot succeed in distinguishing good arguments from bad arguments until we learn to listen carefully to others. Part I develops a relativistic account of argument cogency that allows for rational disagreement. Part II offers a comprehensive and rigorous account of argument diagramming.