The Number of Categories: Al-Fārābī and Yaḥyā Ibn ʿAdī on an Aristotelian Problem

Aristotle’s assertion that there are ten categories representing distinct types of predication sparked extensive debate among Peripatetic philosophers. Some upheld this classification, while others proposed alternative structures. Ammonius Hermiae and later Islamic thinkers like Ibn al-Muqaffaʿ and al-Kindī introduced hierarchical frameworks, prioritizing the first four categories (substance, quantity, quality, and relation). The translation of Categories into Arabic, particularly by Isḥāq b. Ḥunayn, fueled further discussions, especially within the Peripatetic school of Baghdad. This article examines the views of al-Fārābī and his student Yaḥyā Ibn ʿAdī, who defended Aristotle’s tenfold classification against challenges from kalām scholars. While both employed similar argumentative techniques, al-Fārābī adhered closely to Aristotelian principles, whereas Ibn ʿAdī’s Christian background influenced his approach. Through their works, this study explores the broader debate on the nature and number of categories in Islamic philosophy.