ABSTRACT
Aristotle's pupil Theophrastus, along with Eudemus, is famous for having rejected his master's doctrine about mixed necessity-syllogisms in the first figure. The theory of Theophrastus and Eudemus constitutes a clear and a principled challenge to Aristotle's authority in modal syllogistic. In fact, Sosigenes's thesis is consistent with Theophrastus's view that an unconditional necessity never follows from premises one of which is non-modal. Whereas Aristotle had preferred to consider the premises of modal syllogisms according to whether they were necessity- or contingency-propositions, Theophrastus preferred to consider necessity- and possibility-propositions. Alexander wrote a commentary on the Prior Analytics which, apart from expounding the Aristotelian text, contains many passages that frustrate the reader in search of theory and system, because they outline arguments on both sides of a question without finally endorsing one or the other. This chapter concentrates on what Alexander has to say about the notion of possibility, inseparable accidents, types of necessity-proposition, necessity-syllogisms, and contingency-syllogisms.
