Aristotle and the fourth figure of categorical syllogism

The fourth figure of categorical syllogism known as Galen's figure was not presented by Aristotle. This has prompted logicians to launch investigations to find out why Aristotle has ignored it. Some Western Aristotelian scholars believe the standard on the basis of which Aristotle has divided syllogistic figures does not produce anything more other than the three syllogistic figures. They have attributed to Aristotle some criteria which do not result but in three syllogistic figures. The question why Aristotle has not dealt with the fourth figure has also been attended by Muslim logicians. Following Aristotle they did not deal with the fourth figure when logic was experiencing its translation and commentary phase, but they did so not because Aristotle's standard could not produce such a form but because they thought Aristotle ignored the fourth figure for according to him it was unnatural and disharmonious. This article critically assesses the opinion expressed by Western Aristotelian scholars and lays stress on the fact that Aristotle's standard is the same as that of the later logicians who treated that question of the fourth figure. It also objects to the justification put forth by Muslim logicians for not paying attention to the fourth figure.