The Requirements of Motion Philosophers have considered six...

The Requirements of Motion Philosophers have considered six things to be requirements of motion: origin ( mabdā’ ), end ( muntahā ), time, distance, subject ( mutaḥarrak ) and agent ( muharrik ). 1 & 2. Origin and end. Some of the definitions of motion suffice to warrant the requirement of an origin and end for every motion. For example, ‘the gradual emergence of actuality from potentiality’ implies that at the beginning a potentiality should exist and at the end of the motion an actuality.

Hence, potentiality and actuality may be considered the origin and end of motion. It appears that motion does not essentially require a relation to an origin or end, and hence, the assumption of infinite motion without beginning or end is not an irrational one. Accordingly, some ancient philosophers considered the motions of the celestial spheres to be without beginning or end in time, and so they had to take quite some pains to associate some origin and end with them.

It may be said that origin or end are specific to limited motions, and that origin or end are implied by their limits, not implied by the motion itself, as every limited extension has an origin or end. Perhaps the source of the plausibility of considering motion to have an origin or end is that a means is thereby sought to determine the direction of motion. Anyway, origin or end cannot be considered requirements of all motions.

It is necessary to mention that those who consider motion to require an origin or end do not take them to be within the motion itself, because every part of motion is extended, and no matter how small a part is imagined, it will be divisible, and again it will have to have a beginning part. If a part of motion is called the origin or end of motion, this will be a relative attribution to the motion itself.

Taking potentiality and actuality as the origin and end of motion involves a certain laxity, for the terms origin and end are abstracted from the limits of motion, like point for line and moment for time, and they are considered to have an aspect of non-being. This is contrary to potentiality and actuality (especially the latter) which cannot be considered cases in which there are aspects of non-being.

Furthermore, the requirement of potentiality and actuality has not been established for motion, and it may be said that in order to abstract the concept of motion it is not necessary to take into account anything more than the gradual existence of a substance or accident.