In this paper, we consider the way that web documents seeking to persuade readers of certain science claims provide information about the sources of the arguments. Our quantitative analysis reveals that web documents in our sample include hundreds of examples in which the reader is provided information regarding the trustworthiness of sources. The web documents also contain a large number of examples in which the reader is provided with information about how many individuals hold a particular belief. We discuss ad (...) hominem, ad verecundiam, and ad populum arguments, and the way that the examples found in our sample of documents are related to these argumentation schemes. (shrink)

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)