Abstract
<jats:p>Quiddity and Existence in Avicenna and His Commentators In order to elucidate the ontological otherness between the Necessary Existent and contingent existents, Avicenna made a real distinction, to a certain extent, between quiddity and existence; he maintained that in contingent existents, existence is an accidental concomitant to quiddity, whereas in the Necessary Existent, existence and quiddity are identical. This theory, which profoundly influenced the post-classical Islamic intellectual tradition, underwent various transformations within philosophical and theological systems. The present study aims to identify the critical thresholds of this doctrinal transformation, which centered on the Avicennian theory of quiddity, through the commentaries on al- Ishārāt by Fakhr al-Dīn al-Rāzī and Naṣīr al-Dīn al-Ṭūsī. To this end, key texts -primarily al-Ishārāt and its related commentaries- are presented in their original Arabic alongside their Turkish translations and are analyzed comparatively. The first chapter of the study presents a comprehensive analysis of the constitutive elements (muqawwimāt) of quiddity, its causes, and its considerations (iʿtibārāt). The second chapter addresses the senses of existence, its causes, and Avicennas theory of ontological modulation (tashkīk al-wujūd). The third chapter discusses the relationship between quiddity and existence in the context of the Necessary Existent and contingent existents; furthermore, a detailed investigation into the ontological status of absolute quiddity is conducted. In conclusion, by tracing the transformations that the distinction of quiddity and existence underwent in post-classical Islamic metaphysics through primary sources, this study offers a comprehensive and systematic reading of the philosophical legacy formed around the axis of Avicenna and his commentators. Keywords: Islamic philosophy; Avicenna; Quiddity; Existence; al- Ishārāt; Tashkīk al-wujūd; Fakhr al-Dīn al-Rāzī; Naṣīr al-Dīn al-Ṭūsī</jats:p>