This study works through some of the theoretical issues that have been accumulating in informal logic since 1979. At the same time, it defines a core position in the theory of argument in which those issues can be further explored. The underlying concern that motivates this work is the health of practice of argumentation as an important cultural artifact. A further concern is for logic as a discipline. Argumentative and dialectical in nature, this book presupposes some awareness of the theory of argument in recent history, and some familiarity with the positions that have been advanced.