 Avempace links the inversion to the introduction of the fourth figure of the syllogism in which the middle term is the predicate of the premise containing the predicate of the conclusion and the subject of the other premise. “Since [Aristotle] discourses on the action of the syllogistic potency, he keeps perceiving the fourth figure that Galen thought he had ignored” (IB-taaliq: 184. 20–21).