A Study of Priority and Posteriority through Substantiality and its Historical Background in Islamic Philosophy

Priority or posteriority through substantiality or quiddity is considered to be consistent with the theory of the principiality of quiddity, and its application in the system of the principiality of existence has been merely limited to the priority of genus and differentia to species. Through explaining the meaning of substantiality and its difference from substance, this paper examines the former term in Islamic philosophy and clarifies its process of development and applications. This term was propounded for the first time in Suhrawardī’s works and, later, Mīr Dāmād distinguished the referents of this kind of priority from those of priority by essence and introduced it as one of the three types of essential priority. Priority through substantiality has several applications in the system of the principiality of quiddity, such as the priority of the causes of the rational consistency (genus and differentia) or external consistency (matter and form) of quiddity to quiddity, the priority of quiddity to its quiddative and ontological concomitants, and the priority of quiddity to existence. After Mullā Ṣadrā, because of the dominance of his theory of the principiality of existence, the referents of priority and posteriority by substantiality decreased and were limited to those which were in conformity with the system of the principiality of existence. In contrast, the other referents of this kind of priority have been considered to be among those of priority and posteriority by truth.