Theophrastus

Aristotle’s pupil and successor at the head of the Lyceum, who extended his teacher’s syllogistic; few of his writings reached Arabic, but al-Fārābī follows him on ‘metathetic’ negation and Ibn Sīnā names him among the Greek authorities in logic.

Life

Theophrastus was born at Eresus on the island of Lesbos around 371 BCE and studied with Aristotle. When Aristotle left Athens after the death of Alexander the Great in 323 BCE, Theophrastus succeeded him at the head of the school, the Lyceum or Peripatos, and led it for about thirty-five years. He died around 287 BCE.

In logic he developed Aristotle’s syllogistic in several directions. He added to the four moods of the first figure five further moods that Aristotle had mentioned in Prior Analytics II (known in medieval Latin as Baralipton, Celantes, Dabitis, Fapesmo and Frisesomorum), and established that the universal negative proposition converts. He worked out arguments with conditional and disjunctive premises, distinguished three figures of ‘wholly hypothetical’ syllogisms, and introduced so-called prosleptic syllogisms. In modal logic he defined possibility so that it no longer implies non-necessity, and held that in a mixed modal syllogism the conclusion follows the weaker premise (the rule later called ‘in peiorem’). His logical writings, among them On Affirmation and Denial, Prior and Posterior Analytics, On the Analysis of Syllogisms, Topics and On the Liar, are known today from their titles and from reports in later authors.

Arabic writers knew of Theophrastus’ life, works and sayings, but only two genuine works of his survive in Arabic translation, the Metaphysics and the Meteorology, neither of them logical. The Stanford Encyclopedia gives three reasons why he was little copied or quoted in Arabic: the Baghdad school’s promotion of Aristotle eclipsed the other Peripatetics; his questioning style and his use of the same titles as Aristotle made his works unsuited to building a systematic Aristotelianism; and after about 1050 the dominance of Ibn Sīnā led to the disappearance of manuscripts. Some of his logical teaching nonetheless reached the Arabic logicians: al-Fārābī follows him in calling negation attached to a noun (as in ‘not-just’) ‘metathetic’ (ʿudūlī) and in treating the resulting sentence as an affirmation, and Ibn Sīnā names him among the Greek authors whose views he records in his logical works.

Works

• On Affirmation and DenialLost; known from reports in later authors.تصنیف
• Prior Analytics, Posterior Analytics, On the Analysis of Syllogisms, Topics and other logical worksWorks of his own under titles also used by Aristotle; lost.تصنیف

Reception

Al-Fārābī’s term ‘metathetic’ (ʿudūlī) negation follows Theophrastus (SEP, ‘al-Farabi’s Philosophy of Logic and Language’, citing Fortenbaugh et al. 1992).

Ibn Sīnā’s logical writings name Theophrastus among the Greek authorities, together with Plato, Alexander of Aphrodisias, Galen, Porphyry, Themistius and Philoponus (SEP, ‘Ibn Sina: Logic’).

Of his genuine works only the Metaphysics and the Meteorology survive in Arabic; one manuscript ascribes the Metaphysics translation to Isḥāq b. Ḥunayn, while Ibn al-Nadīm credits Yaḥyā b. ʿAdī (D’Ancona, SEP).