Abstract

Perhaps the strangest controversy in the history of logic is that over the fourth figure of the syllogism. There was never any argument as to what syllogisms are valid, but merely as to how they should be arranged. Aristotle had divided syllogisms into figures according to whether the middle term was subject of one premiss and predicate of the other, or predicate of both premisses, or subject of both. Theophrastus and Eudemus subdivided the first figure into those moods in which the middle term was subject of the major premiss and those moods in which the middle was predicate of the major premiss. The latter moods were termed indirect. Galen said they constituted a separate figure; and so the controversy started. It has continued to the present with many writers objecting to the fourth figure, generally on grounds that it does not represent a genuine process of thought, and even ascribing this objection to Aristotle. The issue has been joined by writers who believe that it does represent a genuine process of thought.