From the Simplicity of the Divine Essence to the Unity of Being: A Comparative Examination of the Infinitude of the Necessary Existent in the Islamic Philosophical–Mystical Tradition

The problem of the infinitude of the Necessary Being is one of the most fundamental issues in philosophical and mystical theology within Islamic thought. Philosophers from Ibn Sīnā (Avicenna) to Mullā Ṣadrā have considered divine infinitude as a direct consequence of the Necessary Being’s essential necessity and absolute simplicity, whereas the mystics have interpreted it in terms of the personal and absolute unity of existence. This study aims to provide a comparative explanation of these two approaches and to analyze their logical implications, focusing on the relationship between the infinite nature of the Necessary Being and the unity of existence. The research employs an analytical–comparative methodology, based on textual and conceptual analysis of philosophical and mystical sources, in order to compare the epistemological and ontological foundations of both traditions. The findings show that once the actual infinitude of God—which is equivalent to the simplicity of the Necessary Being—is accepted, the personal and absolute unity of existence must logically follow, since within the presence of an infinite and boundless Being, no independent reality can remain. Consequently, theories such as existential interpenetration or dual-layered reality are inconsistent with the premises of divine infinitude. The study concludes that the infinitude of the Necessary Being, both logically and ontologically, entails the personal unity of existence and the system of manifestation (tashʾun), wherein Islamic philosophy and mysticism ultimately converge upon the same truth.