In the last quarter-century, the emergence of argumentation theory has spurred the development of an extensive literature on the study of argument. It encompasses empirical and theoretical investigations that often have their roots in the different traditions that have studied argument since ancient times – most notably, logic, rhetoric, and dialectics. Against this background, I advocate a “thick” theory of argument that merges traditional theories, weaving together their sometimes discordant approaches to provide an overarching framework for the assessment of arguments (...) in a broad range of contexts. In sketching such a theory, I propose six steps that can “thicken” traditional approaches to argument in the interests of a comprehensive theory. (shrink)