An Evaluation of Fakhr al-Din Razi's Criticisms of Ibn Sina's Definition of Time

Following Aristotle, Ibn Sina maintained that time is the number of motion which is attained by the continuous movement of a moving agent over a distance. He adduced two arguments in order to demonstrate his theory: one was based on the difference between the motions of moving things in terms of speed, and the other was based on the divisibility of the distance of movement. In contrast, through advancing various objections, Fakhr al-Din Razi challenged this theory not only with regard to its two underlying arguments but also with respect to the theory of time being the number of motion. The present paper aims to demonstrate that Fakhr al-Din Razi’s criticisms originate in his lack of enough scrutiny of Ibn Sina’s principles, particularly regarding the opposition of non-existence and habit between motion and rest, time as necessary by the other and not necessary by itself, the difference between universal and particular times of each motion, and the existence of logical fallacy in some arguments. However, the final response to some of his criticisms are given based on the principles of the Transcendent Philosophy regarding the analytic differences between motion, time, and time as the fourth dimension of being.