Galen

Greek physician and philosopher who also wrote on logic; his great work On Demonstration is known largely through Ḥunayn b. Isḥāq, al-Fārābī argued against him on modal logic, and the fourth figure of the syllogism came to be attributed to him.

Life

Galen was born in 129 CE in Pergamon, in present-day Turkey. He trained in Smyrna, Corinth and Alexandria, moved to Rome in the early 160s and settled there for good. The traditional date of his death is around 200. His medical and philosophical work had enormous influence in the Middle Ages, and some of his works survive only in Arabic, Syriac, Hebrew or Latin translation.

His most important work on logic, On Demonstration, is lost except for fragments; a shorter Introduction to Logic (Institutio logica) survives. In a lost commentary on the Categories he added an eleventh category, ‘composition’. He discussed the Stoic hypothetical syllogistic in detail and criticised the Stoics on several points, insisting on the priority of things over expressions, and he claimed as his own innovation the ‘relational syllogism’ (Introduction to Logic 16), for arguments such as: Theo has twice what Dio has, Philo has twice what Theo has, so Philo has four times what Dio has. There is some suggestion that he posited a fourth figure of the syllogism beside Aristotle’s three, but the Stanford Encyclopedia notes considerable doubt both about the value of such a figure and about Galen’s authorship of it, and prefers to read the reports as concerning compound syllogisms.

Galen reached Arabic first through Syriac. Sergius of Reshʿaynā (d. 536) translated about thirty of his treatises into Syriac, and in the ninth century Ḥunayn b. Isḥāq and his circle translated a great number of his works into Arabic; Ḥunayn’s letter to ʿAlī b. Yaḥyā lists them. What is known of On Demonstration comes largely from Ḥunayn’s listing of it, and the Stanford Encyclopedia describes Ḥunayn’s circle as ‘not unequivocally Aristotelian’ in logic. Al-Fārābī argued, against Galen, that logic with possibility statements is useful in practical arts such as medicine, agriculture and navigation, and Ibn Sīnā names Galen among the Greek authorities in his logical works. In the twelfth century Ibn al-Ṣalāḥ (Aḥmad b. Muḥammad, d. 1153 or 1154, not the Damascene hadith scholar of the same name) wrote a treatise On the Fourth Figure of the Categorical Syllogism, which Nicholas Rescher edited and translated in 1966 in a study of the claim that Galen originated that figure.

Works

• On DemonstrationHis main logical work; lost except for fragments. Known in Arabic largely through Ḥunayn b. Isḥāq’s listing of it (SEP).eser
• Introduction to Logic (Institutio logica)Survives in Greek; chapter 16 introduces the relational syllogism.eser
• Commentary on the Categories — üzerine AristotelesLost; reported to add an eleventh category, composition.şerh

Reception

Ḥunayn b. Isḥāq translated 129 of Galen’s works from Syriac into Arabic with a team of collaborators, under the patronage of the Banū Mūsā (TDV).

Al-Fārābī’s claim against Galen on the usefulness of modal logic is known from his commentary on On Interpretation and from quotations in Maimonides (SEP).

Abū Bakr al-Rāzī wrote Kitāb al-Shukūk ʿalā Jālīnūs, a critique of Galen’s medical and philosophical views (TDV).

Nicholas Rescher, Galen and the Syllogism (1966), examines the attribution of the fourth figure to Galen in the light of Arabic sources and edits Ibn al-Ṣalāḥ’s treatise on that figure.