In just the last twenty years there has arisen a strong interest, especially among teachers of logic at the universities, in teaching techniques of applied logical reasoning and critical thinking. Many universities are now stressing these skills at an introductory level, and to meet the need, informal logic has begun to form and grow as a discipline in its own right. Like all subjects, it helps us to understand it if we can situate it in a context of historical development. This collection of essays provides the readings required to understand the development of a subject whose historical origins have been so far little studied. Many of the chapters are written by scholars in philosophy and speech communication who are themselves leading contributors to the subject, and their contemporary views throw light on how these earlier writers have influenced their thinking. This dimension gives an added interest to the essays, and indicates the way informal logic is currently evolving and seeking out its ancient historical origins.