Stanford Encyclopedia of Philosophy
Informal logic is an attempt to develop a logic that can assess and analyze the arguments that occur in natural language (“everyday,” “ordinary language”) discourse. Discussions in the field may address instances of scientific, legal, and other technical forms of reasoning (and notions like the distinction between science and pseudo-science), but the overriding aim has been a comprehensive account of argument that can explain and evaluate the arguments found in discussion, debate and disagreement as they manifest themselves in daily life — in social and political commentary; in news reports and editorials in the mass media (in newspapers, magazines, television, the World Wide Web, twitter, etc.); in advertising and corporate and governmental communications; and in personal exchange.
Groarke, Leo. (1996). Informal Logic. Stanford Encyclopedia of Philosophy.