Porphyry’s Isagoge between Baġdād and Hamaḏān: Yaḥyā Ibn ʿAdī and Avicenna on Individuality

The Kitāb al-Šifāʾ is by far the philosophical summa in which Avicenna’s allegiance to previous exegetical tradition is most evident, thus representing a unique standpoint to the inquiry into Avicenna’s sources. The present paper aims at showing how the Kitāb al-Madḫal of the Šifāʾ is able to provide new insights into Avicenna’s reception of Porphyry’s Isagoge and to allow a more precise study of Avicenna’s acquaintance with previous and contemporary literature on the subject. As a result of the survey, new evidence is found that allows reconstructing a debate between Avicenna and leading Baġdād Aristotelians like Yaḥyā Ibn ʿAdī concerning the notion of ‘individual’ in logic.