  Aristotle’s investigations into logic and the forms of argumentation make up part of the group of works coming down to us from the Middle Ages under the heading the Organon (organon = tool in Greek). Although not so characterized in these terms by Aristotle, the name is apt, so long as it is borne in mind that intellectual inquiry requires a broad range of tools. Thus, in addition to logic and argumentation (treated primarily in the Prior Analytics and Topics), the works included in the Organon deal with category theory, the doctrine of propositions and terms, the structure of scientific theory, and to some extent the basic principles of epistemology.