Among the primary divisions which can be made for existence is that between the immutable and the changing. The immutable includes the Necessary Existent and completely immaterial beings. The changing includes all material existents and souls that are attached to matter.
Changes may be divided into two kinds: sudden and gradual. The gradual is that which is called ‘motion’ in philosophical terminology, and opposed to this is the concept of being stationary, which is its relative complement (‘adam malikah); that is, it is not the case that everything which lacks motion necessarily has the attribute of being stationary, but those things which have the capacity for motion but in actuality are not in a state of motion will be stationary.
Therefore, completely immaterial existents cannot be called stationary. From this, the difference between the concept of being stationary and that of being immutable is clear: the former is the relative complement of motion, while the latter is the contradictory of change.
In this part, we will first give an explanation of the immutable and the changing and the types of change and alteration, and then we will discuss motion, prove the existence of motion, and present the implications and kinds of motion. Along the way we shall explain the concepts of potentiality and actuality, and the relation between these and change and motion. Finally, this part, which is the last part on first philosophy, will be brought to an end with a discussion of substantial motion.
In Arabic, the word for change, taghayyur, is derived from the word for other, ghayr, and means becoming another, or becoming different. Change is a concept whose abstraction requires the consideration of two things or states, or two parts of one thing, one of which vanishes and is replaced by the other.
Even the obliteration of something may be called a change since its existence changes to nonexistence, that is, it becomes annihilated, although nonexistence has no reality, and temporal coming into existence (huduth) also can be called change, for the previous nonexistence is changed into existence.
Alteration and change in state (tahawwul) are also close to change, but since tahawwul is derived from hall (state), it is more suitable to confine its use to changes in state. From this it may be observed that the concept of change is not a whatish concept for which genus and difference may be given, and it is only with difficulty that a clearer intellectual concept may be found which could be used to explain it, and for this reason it must be considered a self-evident concept.
Likewise, the concept of immutability, which is the contradictory of change, does not need any definition or explanation, and since it is abstracted from a single entified existence, it may be considered a positive concept and change a negative one. Perhaps for this sort of opposite abstracted concepts, either of them may be considered positive and the other negative.
The existence of the changing is also self-evident, and at the very least every person finds changes within his own internal states by presentational knowledge. However, immutable existence, which is not the object of any sort of change or alteration, must be established by proof. And in the previous part we became acquainted with some such proofs.
Given the breadth of the concept of change, various kinds of change may be posited:
1. The appearance of a substantial existent without previous matter, and in technical terms, creation (ibda‘i). Instances of this posit is the first material existent, for those who accept the temporal beginning of the material universe.
2. The complete destruction of a substantial existent and an instance of it is the last material existent, according to the position of those who believe that the material universe will have a temporal end.
3. The complete destruction of a substantial existent and the appearance of a new substantial existent in its place. The occurrences of this posit is considered impossible by most philosophers, and at the very least it may be said that among ordinary phenomena no instances of this sort of change are to be found.
4. The appearance of a substantial existent as an actual part of another substantial existent. A clear instance of this is vegetable forms, according to the position of those who consider vegetable forms to be substantial, and their materials to be actual existents.
5. The destruction of a part of a substantial existent without being replaced by another part, such as the death of a plant and its decomposition, according to the above-mentioned position.
6. The destruction of an actual part of a substantial existent and the appearance of another part in place of it, a clear instance of which is ‘generation and corruption’ such as the transformation of one component into another.
7. The destruction of a potential part of a substance and the appearance of another potential part in place of it. An instance of this posit is the substantial motion of bodies, which incessantly occurs with the destruction of one part and its replacement by another, parts which become existent by fluid existence and in which no actual part is to be found. In future lessons this will be further explained.
8. The coming about of a new accident in a substantial subject, of which there are numerous instances.
9. The destruction of an accident without another accident taking its place, such as the fading of the color of a body and its becoming colorless.
10. The destruction of an accident and the appearance of a different accident in its place, an instance of which is the succession of contrary accidents, such as the colors black and white.
11. The destruction of an actual part of an accident. An instance of this is the reduction of the number of something, according to those who consider number to be a real accident possessing actual parts.
12. The addition of an actual part to an accident, such as the augmentation of the number of something according to the above-mentioned view.
13. The destruction of a potential part of an accident and the appearance of another potential part, such as all accidental motion.
14. The attachment of one substantial existent to another, such as the attachment of the soul to the body and its coming to life.
15. The detachment of one substantial existent from another, such as the death of an animal or human being.
Observing the features of the above-mentioned types of change, it is clear that only the seventh and the thirteenth types are gradual and are examples of motion. The other types must be considered instantaneous changes, for between the prior and latter conditions there is a specific boundary, and there is no temporal gap between them, although it is possible for each of the above- mentioned conditions to possess a kind of gradualness.
For example, a change in the temperature of water occurs gradually, although the transformation of water into steam occurs in a single moment, or a zygote gradually becomes complete, but a spirit becomes attached to it in a single moment. Given this point, changes can be divided into two general types: instantaneous and gradual.
Another point is that for every kind of gradual change (types seven and thirteen) three subtypes can be considered: one is that in which the earlier parts are like the later parts, such a motion at a constant speed without acceleration; the second subtype is that in which the later parts are more intense and stronger than the earlier parts, such as intensifying motion and speeding up; and the third subtype is that in which the later parts are weaker than the earlier parts as in decelerating motion and slowing down. However, there is some controversy about this which will be indicated later.
A review of the statements of the philosophers regarding each of the mentioned types of change would take too long; however, five positions in this area may be indicated.
1. The well-known position of the philosophers who consider the appearance of every material phenomenon to be necessarily preceded by matter and time, and as for the material world, they hold that it does not have a temporal beginning or end, and for this reason they deny the first three types of change.
2. The position of those who hold that numbers are respectival is naturally that changes in number are not real changes, and this position was previously confirmed. Therefore, changes of types eleven and twelve must be considered respectival.
3. The position of those who do not consider motion to be gradual, and who imagine all changes to be instantaneous. Accordingly they deny the seventh and thirteenth types. Since the concept of change is an abstract concept, and has no example other than prior and later existence and nonexistence, and nonexistence is pure nullity, for this reason they considered existence to be equal to immutability, such as some of the Eleatics of ancient Greece.
4. The position of those who accept the existence of motion but would restrict it to accidents and as a result they deny the seventh type of motion.
5. The position of Sadr al-Muta’allihin and others who believe in substantial motion.
Given that which was stated in Lesson Forty-Seven about number, where it was proved that number is respectival, there is no further need for discussion of changes in number. However, regarding the other positions, several problems should be discussed.
The first problem is that of whether material phenomena must necessarily originate in previously existing matter, so that it would follow that the chain of material events stretches from pre-eternity infinitely and without beginning, or whether they must originate in an existent which is at the head of a chain of material phenomena so that the chain of material events has a temporal beginning.
The second problem is whether motion, as a continuous gradual thing, exists in the external world or whether that which is called motion is a collection of fixed things which are brought about in succession and destroyed, so that the mind of man abstracts the concept of motion from their collection. In other words, are all changes instantaneous, or are there also gradual changes?
The third problem, after establishing that there is motion, is whether gradual change occurs only in accidents, or whether there can also be motion, or motions, in substance itself.