It has long been known and taught that ambiguity is associated with certain fallacies, or logical errors of reasoning. However, as Hambling (1970) documented, the traditional treatment of these fallacies in logic textbooks tends to be quite superficial, and is characterized by a number of basic problems, unanswered questions, obscurities, and inconsistencies. As a scholarly contribution to the field of philosophy, this book sorts out these problems by giving clear and useful guidelines that can be used to evaluate cases where a fallacy arising from ambiguity is said to occur. The book breaks new ground not only by giving analyses of the various fallacies arising from ambiguity themselves, but also by basing these analyses on a new pragmatic approach to the concept of ambiguity. Indeed, the book argues that ambiguity is itself ambiguous, and not easy to define clearly. However, it does advocate a new classification of types of ambiguity that is shown to be useful in helping to evaluate cases of fallacies arising from ambiguity. Bringing some order to this area is a big advance, because it is a very disorderly subject indeed, judging from the accounts given in the traditional and current textbooks of informal logic and critical thinking.