Jacob E. Van Vleet’s book on informal fallacies is an important reminder of what is typically left out in the study of logic that all too often is confined to formal logic, to the study of rules of inference and the abstractions that proceed from the granting of those rules. Informal fallacies are psychologically persuasive and arise within the marketplace, the common world; studying them may enable us to think for ourselves amid our current blather of clichés and tweets.