Soul Affection and Change in the Nature of Conceiver: An Aristotelian Problem, An Avicennaean Conjecture and a Sadraean Defense

In Peripatetic Philosophy, soul is regarded as the capacity of perception and because of perception is a kind of alteration, the explanation of change in soul has an important place. In the fifth chapter from the second book of de anima, Aristotle says about some kind of alteration which demands the change in the nature of conceiver and so it is different from the natural alteration. This kind of alteration requires the perfection of soul’s nature in the course of intellection, so corresponds to the concept of substantial change and the unity of intellect and intelligible. But Avicenna has denied the possibility of this special kind change i.e. the change in the nature of intellect. Appealing to the concept of substantial movement and higher being of essence, a Sadraean solution to the Aristotelian soul affection has been proposed, which can explain the soul affection as a change in the nature of conceiver. Although due to two different conceptions of unity of intellect and intelligible, two solutions are possible to solve the ascription of perception to the nature of conceiver.