Man has always been a witness to changes and alterations in bodies and in souls attached to matter, so that it may be claimed that there is no material existent nor existent attached to matter which is not subject to some kind of change or alteration. In the appropriate place the necessity of substantial motion will be proved for all material things, implying that changes in their accidents are subordinate to substantial motion.
On the other hand, the scope of the alteration of an existent into another existent such that each of them possesses an independent whatness becomes so broad that it may be supposed that each material existent can change into another material existent.
Hence, from the earliest times it has been held that there is a single principle for the world which changes into different things with the transformations which occur in this principle. Many philosophers have held that the only exceptions to this doctrine are the celestial bodies. In other words, the subjects to which this doctrine applies are limited to elemental bodies.
Aside from the invalidity of the assumption of unchangeable celestial spheres (aflak), by rational proof one cannot deny the possibility that there might be a kind of material existent in some unknown corner of the world which cannot be changed into another material existent, although this possibility seems extremely weak and farfetched. We know that in modern physics the commonly accepted theory is that matter and energy and even types of energy can change into one another.
Despite the generality of alteration in relation to all material things, and the breadth of the scope of changes, practical experience shows that not every thing may be directly changed into anything else. Even if all material existents could be changed into one another, this could never be accomplished directly and without mediation.
For example, a stone cannot directly change into a plant or an animal. In order to be transformed into a plant or animal it must go through several stages and alterations must take place until it is prepared for such transformations.
Such thoughts have led philosophers to think that only an existent can change into another existent when it possesses the potentiality of the existence of the other. In this way the term potential and actual appeared in philosophy, and change came to be interpreted as emergence from potentiality to actuality. If this occurs instantaneously without a temporal gap it is called ‘generation and corruption.’ If it occurs gradually and with temporal gaps, it is called motion.
The word potential (quwwah), whose literal meaning is power and ability, has various technical meanings in the sciences, and in philosophy it is used in several senses. The first is the potentiality of an agent who is the source of the production of an action. It seems that this is the first sense which was noticed by philosophers and whose relation to ‘action’ is clear.
It was then imagined that just as prior to performing a deed the agent has the ability to accomplish it, matter must also possess ability, readiness for acceptance and passivity in advance. In this way a second meaning appeared for potential. This can be called passive potential (quwwah infi‘ali), and in this discussion it is this sense which is intended.
The third meaning of potential is resistance to an external factor, such as the resistance of the body to disease, and the opposite of this is called lack of potential (la quwwah), and these are two kinds of dispositional qualities.
It should be noted that the use of ‘potential’ by philosophers is more general than disposition (isti‘dad), for the term potential is also applicable to substance, contrary to disposition which is a kind of accident. However, it was previously mentioned that substantial potential (prime matter) is not provable, and disposition is also an abstract concept, not an essential concept.
Likewise, the concept of passive potential is abstracted by the comparison of two existents, prior and posterior, since the prior existent lacks the posterior existent and it is possible for the prior to possess the later. Therefore, at the very least a part of the prior existent must remain and have a kind of composition and union with the posterior existent.
Contrary to this, the expression ‘actuality’ is used as a result of abstraction from occurrence of the posterior existent. Hence, potentiality and actuality are two abstracted concepts neither of which is to be considered an essential concept.
Sometimes the expression actual (bil-fi‘l) is used in a broader sense to include even existents which have no previous potentiality, and it is in this sense that complete immaterial existents are called actual existents.
We should remind the reader that in some philosophical discussions, the existence of something shared between the potential and actual existents is neglected, and, for example, the earlier parts of time and motion are called potential in relation to the later parts, and it seems that this usage is not free from imprecision.
If the expression ‘actual’ is taken in its general sense which includes immaterial existents, then another primary division of existents may be considered between actual existents and potential existents. The potential existents are to be found among materials, while actual existence embraces immaterial existents and the actual aspects of material things.
However, it must be observed that this division is similar in some respects to the division of existents into causes and effects or objective existents and mental existents, and not like the division of existence into the immaterial and the material.
This is explained by the fact that sometimes a division is made by adding two or more absolute (nafsi, i.e., not relative) concepts to that which is divided so that the subdivisions do not overlap, as in the division of existents into the immaterial and material; that is, a material existent can never in any way be considered an immaterial existent and the immaterial can never be viewed as material.
In other cases, a division is made through the use of relative concepts, and therefore it is possible for some things in one subdivision to be considered as being in the other, as in the division between cause and effect, that is, an existent may be considered a cause with respect to one thing and with respect to another an effect. The same is the case for mental concepts which are called mental existents with regard to the standard of objectivity, but are considered objective existents in so far as they exist in the realm of the mind.
The division of existents into the actual and the potential is of the same sort, for a potential existent in relation to an actuality which it can possess is called potential, even though with respect to the actuality which it possesses at present it will be an actual existent.
Hence, the aspects of potentiality and actuality are not entified aspects, and their concepts are not to be considered absolute (nafsi). Rather they are relational concepts which refer to intellectual and comparative aspects. This is an important point which we indicated in our criticism of the proof of the Aristotelians for prime matter.
Another issue is that there is a difference between the division of existence into cause and effect and the division into the mental and the objective, for in the division of cause and effect, a cause may be considered which is in no way any sort of an effect, such as the Sacred Divine Essence, and one can also imagine an effect which is completely free of causal agency.
However, other than these, existents will be causes in one respect and effects in another. This is contrary to the case for the division of existents into the objective and the mental, for no existent can be found which has no kind of objectivity whatsoever, but rather all mental existents, aside from the fact that they refer to other things, are objective existents.
Now the question will be raised as to which of these two sorts of divisions is that between actual and potential existents. The answer is that the Aristotelians assumed that this division was like that between cause and effect, for they viewed complete immaterial existents to be actual without any potentiality, prime matter as potentiality without any actuality, and bodies as possessing aspects of both potentiality and actuality.
However, those who do not accept a matter which lacks all actuality, as is required by the principle of ‘the equivalence of actuality and existence,’ will therefore view the division as entirely similar to that between the mental and the objective.
As we have learned, the concepts of potentiality and actuality are abstracted concepts, and aside from the sources from which they are abstracted, they have no other entified instances. Hence, the relation between the potential and the actual is really a relation between two existents which are the sources of the abstraction of these concepts. In other words, what should be considered is the relation between the potential and actual existents.
This relation occurs in one of two forms: first, when a potential existent remains completely within the actual existent, and in this case, the actual existent will be more perfect than the potential one, as the plant is more perfect than the soil of which it is brought into existence; second, when only a part of a potential existent remains within the actual existent, in which case it is possible that the destroyed part is replaced by another part which regarding its level of existence is equal to, less perfect than, or more perfect than the previous one, and as a result, in some changes, the actual existent will be less perfect, or equal to the potential existent.
To be more precise, a potential existent is really the same part that remains, and therefore, the actual existent is always more perfect than or equal to the part that is really the potential existent. Some have imagined that the potential existent is always less perfect than the actual existent, because the potential aspect is an aspect of lacking or absence while the aspect of actuality is the aspect of possession and presence.
When a potential existent is transformed into an actual existent it comes to possess something existent which it previously lacked. On this basis they have denied equivalent and declining motions. On the other hand, the return from actuality to potentiality has been considered impossible, because return is a kind of change, and all change is a transformation of earlier potential into later actuality, but not the reverse.
From this it has been concluded that if a spirit obtains all its perfections so that it is not potential with respect to any further perfection, it will leave the body, and in other words, natural death will occur, and the spirit will never return to the body, for the return of such a spirit to the body would be a return from actuality to potentiality.
Given the explanation of the relation between the potential and the actual existent, it is clear that the aspects of potentiality and actuality are not two entified aspects between which a comparison can be made.
However, the actual existent, that is, the collection of that which remains of the previous existent plus the actuality which is newly obtained, will be more perfect than the part which remains. But it is not necessary that the totality of the actual existent will always be more perfect than the totality of the potential existent, just as one cannot consider water or steam to be more perfect than the other, although they are alternatively transformed into each other.
Regarding equivalent and declining motions, these will be discussed in the appropriate place.1 Regarding the return of the spirit to the body, this has no relation to the return from actuality to potentiality, because the potential has temporal priority to the actual, and with the passage of time it too passes and does not return, regardless of whether the past existence was more perfect, less perfect, or equal to the later existence. In reality, body has the potentiality for the renewed acceptance of the spirit, and with attachment to it, it obtains a new actuality.
Indeed, this mistake originates in the assumption that the aspect of potentiality is the whatness of or a level of the previous existence, for this reason it is supposed that if the level of existence of the later existent were the same as the previous level, a return from actuality to potentiality would occur, while if the later level were weaker than the previous, a return from potentiality to potentiality would occur.
In case the source of abstraction of potentiality is the previous existent itself (and not a kind or level of its existence), the previous existence itself passes with the passage of time and has no possibility for return at all, and the source of the abstraction of the actuality is the later existent itself, regardless of whether the level of its existence and its specific whatness is equal or equivalent to, more perfect than, or less perfect than that of the previous existent.
- 1. Cf., Lesson Fifty-Seven.