Ibn Sina Developing Farabi’s Theory of Perceptual Faculties

Developing existing theories of perceptual faculties, Avicenna delivers an account of five inner perceptions. Beforehand Farabi did not consider any difference between imaginary perception faculty and motekhayelah. However, he mentioned one faculty doing both activities and was usually calling it motekhayelah faculty and sometimes imaginary perception faculty. Avicenna explains the distinctions. Although Avicenna show some features of Farabi’s theory of perception, he has expanded it thus actually new phases are added to it. Conceptualizing imaginary perception with its functions, Farabi deals with three primary activities: storing sensory forms, composing and decomposing sensory forms, and imagery. Avicenna defines what Farabi calls the imaginary faculties as three inner perception, i.e., imagination, estimative and memory faculties. Another development of Avicenna proves that Farabi does not express separately about nature of perception. But he points to the kinds of perceptions in his other discussions. For example, he expresses in his talking about the first lover and pleasure that he enjoys in it. Because of feeling or imaginary perception or rational science and says in his analysis of psychical faculties that the science will be realized by rational, motekhayelah or sensory faculties. In his opinion, rational faculty is responsible for intellectual perception, motekhayelah faculty for imaginary perception and appearance senses for the sensory perception. Avicenna develops the theory, conceptualizing illusion as a kind of perception. We cannot see this term in Farabi’s works. Farabi has defined illusion as an imaginary perception for something that is not existent. While Farabi does not define faculty in his discussions about faculties of soul, Avicenna believes that faculty means both doing origin and acceptance origin. Because the affairs out of self includes movement and perception and faculty about perception means acceptance of origin and stimulation means action from origin. There is no preference to refer faculty to one of these two cases and if one uses the term of faculty for both perception and stimulation faculties, namely both acceptance and doing origins, it will be due to sharing of terminology.