Queen's University at Kingston This paper discusses the systems of evidence and proof used in law, social science and science, leading to an introduction of general credibility and patterns of everyday reasoning in informal scientific writing. For this genre, ethnomethodological and text linguistic approaches are shown to provide methods of understanding that complement and extend traditional philosophical and rhetoric methods. A formal science paper is discussed which deals essentially with

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... clusions and the supporting scientific observations and calculations, with some mention of causes. In a brief journalistic discussion of that paper, however, a broader perspective is taken; causes take on greater importance as they point to the solution to the problem raised by the conclusions. To demonstrate the complex reasoning involved in such articles, the short article is analyzed in detail using text linguistic principles. The individual logical relations and the ways they interact to create complex reasoning are shown to be a necessary part of the understanding of this "summary plus" prose form of explanatory prose.