the mulla sadra’s distinct solution from ibn sina’s on resolving co-existence of two categories in mental existence and its efficiency

although aristotle has considered the “universal substance” as a substance, he introduced knowledge as an accident. the question then arises as to whether a “universal substance”, whereas it is a substance, can be an accident. answering the question, ibn sina has changed the subject of the dispute from “mental substance” to “quiddity of substance”, so that he could guarantee its truth in the form of an “essential artificial common predication” (haml shaye sana’i be-al-dhdhat). considering this change and criticizing ibn sina, mulla sadra has posed “essential primary predication” (haml awwali dhdhati) as a solution. by considering these two solutions, the necessity of posing essential primary predication by sadra can be understood. it also can be well realized that their solutions, despite qawam safari’s claim, are not the same, and sadra’s solution cannot be seen as inefficient, as fallahi says, although it can only solves some part of the problem.