Abstract

According to philosophers, the origins of man's numerous acts are the different faculties of the soul. Although, there are some disagreements between Ibn-Sina and Mulla Sadra on the criterion for the plurality of these faculties, both are unanimous concerning the existence of different faculties.Man's soul is a single reality which is, at the same time, of three different vegetative, animal, and human stages. The faculties related to each of these states could be separately explored. On first division, the faculties of the soul are divided into motive and perceptive types. Some parts of the motive faculties are related to the vegetative aspect of the soul, and some others to its animal aspect. Some of the perceptive faculties are shared by both man and animal, but the rational faculty is restricted to man. Considering the fact that the most important act of the soul is perception, it is necessary to refer to philosophers' theories on the nature of perception. Mulla Sadra believes that the faculties of the soul comprise its grades and modes and emphasizes that "the soul in its unity is all of its faculties". He has drawn on Fakhr Razi's words to a great extent in clarifying this principle.