Informal Logic and the Dialectical Approach to Argument

Undoubtedly, Ralph H. Johnson and J. Anthony Blair are two of the patriarchs of informal logic (IL), and they remain its most recognized exponents. The informal logic movement initially began as a rejection of the tools of formal logic as an effective means of analysing and evaluating everyday reasoning and argumentation. As it developed, IL began to adopt a dialectical conception of its subject matter, and started to utilize the theoretical and methodological tools associated with this approach. This paper explores the influence of the dialectical conception of argument on the development of informal logic. Noting that neither Blair nor Johnson has embraced a dialogic approach to the dialectical, we situate Walton’s dialog-based approach in relation to that of informal logic.