ABSTRACT
Aristotle's influence, which was very great in many different fields, was greatest of all in logic. In late antiquity, when Plato was still supreme in metaphysics, Aristotle was the recognized authority in logic, and he retained this position throughout the Middle Ages. Aristotle's most important work in logic is the doctrine of the syllogism. Syllogisms are of a number of different kinds, each of which has a name, given by the scholastics. The most familiar is the kind called 'Barbara'. All the important inferences outside logic and pure mathematics are inductive, not deductive; the only exceptions are law and theology, each of which derives its first principles from an unquestionable text, viz. the statute books or the scriptures. Apart from The Prior Analytics, which deals with the syllogism, there are other logical writings of Aristotle which have considerable importance in the history of philosophy. One of these is the short work on The Categories.
