Undoubtedly, not just any effect comes into existence with any cause. Even among successive or simultaneous phenomena there is not always a causal relation. Causation is rather a specific relation among certain existents. In other words, between the cause and effect there must exist a specific relation, which can be termed the homogeneity (sinkhiyyah) of cause and effect. This principle is also an intuitive proposition which is close to being self-evident, which may be demonstrated by the simplest of internal and external experiences.
However, there is a difference between homogeneity and the relation which is necessary between cause and effect in cases of existence-giving causes on the one hand and material and preparatory causes on the other.
In the first case, the characteristics of this homogeneity can be established by rational proof, and its demonstration is as follows: Since the existence of the effect is emanated by the existence-giving cause, which can be put roughly by saying that it gives existence to its own effect, it itself must have that existence which it can then give to its effect.
If it did not possess that, it could not grant or emanate it (one who gives something cannot lack it). Noting that granting existence to an effect does not diminish the granter of anything, it becomes clear that it possesses the above-mentioned existence in a more complete form, such that the existence of the effect can be considered its radiance and luminescence.
So, the homogeneity between the existence-giving cause and its effect means that this cause has the perfection of the effect in a more perfect form. If a cause in its own essence did not possess a kind of existential perfection, it would never be able to grant this perfection to its effect.
In other words, every effect is produced by its cause which has the perfection of its effect in a more perfect form. This subject becomes clearer with regard to the relational nature of the effect with respect to its existence-giving cause and the special gradation between them, which were established in the previous chapters.
Homogeneity does not exist between material or preparatory causes and their effects, for such causes do not grant or emanate existence. Their influence is limited to alterations in the existence of their effects. With regard to the fact that not just anything can bring about any kind of change, it is summarily obtained that some sort of relation and homogeneity is also necessary between such causes and effects.
However, the characteristics of this sort of homogeneity cannot be established by rational proof, rather, it is only through experience that one can discern what sort of things can be the source of what changes, and under what conditions and with the aid of what things these changes are produced.
For example, reason, by means of conceptual analysis, would never be able to discover whether water is simple or is composed of other elements, and if the latter, of what and how many elements it is composed. What conditions are necessary for such a composition? Are these supposed conditions replaceable or not?
Hence, it is only by means of experience that it is possible to establish that water is composed in a special way of two elements, oxygen and hydrogen, that this composition requires a certain temperature and pressure and that an electrical current can speed the process of composition.
We have stated that it follows from a rational proof that every existence- giving cause must possess the perfection of its effect, for it is absurd to suppose that the granter lacks that which it grants to another.
With regard to this topic, the following problem may be raised, that an implication of this principle is that existence-giving agents have material existences and their perfections, while an existence-giving agent can only be an immaterial existent which does not have matter or the specific attributes of matter. So how can something emanate that which it itself does not possess?
The answer to this problem is that what is meant by possessing the perfection of an effect is having a more perfect and higher level than the existence of the effect, such that the existence of the effect is considered to be the radiance of the cause, not that the limits of the existence of the effect are exactly preserved in the cause, and not that the cause has the same whatness as the effect.
It is clear that the greater perfection of the existence of the cause than the level of the existence of the effect is not compatible with their whatish unity. One can never abstract a single whatness from two existents which have specific gradation, one of which is considered a plane of the existence of the other and its radiance, because what it means for two existents to have a single whatness is that their existential limits correspond to one another.
This is impossible in the case of two levels of existence one of which is more perfect than the other, having fewer limitations and imperfections. However, lacking the whatness of the effect and the limits of its existence does not mean lacking its existential perfection. That which is necessary in the case of the existence-giving cause is having the existential perfections of the effect in a more perfect and higher form, not possessing its imperfections and limitations.
If the concept of a body and its implications, such as being spatial and temporal, being capable of movement and change, are not true of God, the Exalted, and completely immaterial things, this is because the above-mentioned concepts imply the imperfections and limitations of material existents rather than their perfections.
It should be noted that the solution to this problem became possible by virtue of the fundamentality of existence, and that on the basis of the fundamentality of whatness there would be no correct solution for it, because an implication of the fundamentality of whatness is that that which is in fact emanated from the cause is the external whatness of the effect, and according to this principle the cause must be in possession of this whatness.
It cannot be said that the cause has the whatness of the effect in a more perfect form, for such graduation, especially the specific graduation among whatnesses, is meaningless. As was mentioned in Lesson Twenty-Eight, all immaterial whatnesses, especially simple whatnesses, are disparate from one another. Furthermore, the supposition of a whatness in the case of God, the Exalted, is incorrect.
According to a well-known philosophical principle, from a single cause nothing can be produced but a single effect, (“The one produces nothing other than the one”). However, there are disagreements about the purport of this principle and the cases to which it applies. Among these disagreements is whether by unity of cause is meant individual unity or unity of kind, and whether by unity of cause is meant complete simplicity.
For example, there is the meaning chosen by Sadr al-Muta’allihin in his “Journey of the Soul” in the Asfar, on the basis of which the above-mentioned principle is considered to be specific to the sacred divine essence in the existence of whose essence there is not even analytic complexity, such that the immediate effect of it can only be one existent, and other creatures must be produced by means of one or several intermediaries from this first effect.
Other philosophers have understood this principle to cover other cases more or less as well. Likewise, regarding the concept of ‘production’ (sudur) there are also differences, such as whether it is true of all causal relations, even conditions and preparatory causes, or whether it is restricted to efficient causes, or whether it is limited to existence-giving causes.
In other words, can it be said on the basis of the principle that a preparatory agent cannot have more than one effect, that one condition will have no more than one consequence, and that one natural agent will have no more than one action? In order to determine the cases to which this principle applies, one should examine carefully the reasons in support of it to discover why it is required.
Philosophers have given different kinds of reasons for this principle, but the most clear and at the same time firmest of these is a reason which originates in the principle of homogeneity between cause and effect, which may be expressed as follows: According to the principle of the homogeneity of cause and effect, the cause must possess that which it gives to the effect in a more perfect form.
Now, if it is supposed that the cause possesses just one sinkh (root) of existential perfection (i.e., a homogeneity making factor between cause and effect), naturally its effect will possess a lower level of that perfection, not another perfection. If we suppose that two different effects are produced from one such cause, then, according to the mentioned principle, the cause must possess two roots of perfection, while it was assumed that it only possesses one root of existential perfections.
Several conclusions may be derived from a careful study of this argument.
1. This principle is specific to existence-giving causes, since, as was mentioned, this feature, that the cause must possess the perfection of its effect, is specific to existence-giving causes.
Therefore, on the basis of this principle one cannot establish that natural agents, that is the reasons for changes and alterations in material things, each have a single effect, or that, for example, there is only one thing which is the condition for the effect of an agent, or that there is only one thing which is the preparatory condition for a capability. For example, heat is a condition for various chemical actions and reactions, and heat itself comes into existence by means of various natural factors.
2. This principle is not limited to a single individual, for the above reason also includes unity of kind, and if we suppose that one kind of existence- giving cause has several individuals, and that they all possess one root of existential perfection, then naturally, their effects will all be of one kind.
3. This principle is limited to causes which possess only one root of perfection. However, if an existent has several kinds of existential perfection, or all existential perfections in a simple form, that is, if its existence possesses the above perfections with that same unity and simplicity, then this argument will not cover it.
Therefore, the above-mentioned principle does not establish anything more than the principle of the homogeneity between an existence-giving cause and its effect. The unity of the first thing produced cannot be established merely on the basis of this principle, although there is another way to establish this, which will be presented at the appropriate point.
Another well-known principle is that a single effect cannot be produced by more than a single cause, (“The one is not produced by other than the one”).
Regarding this principle, despite differences, all philosophers agree that a single effect can be produced from a compound cause. So, what is meant by the unity of the cause in the above principle is not simplicity and lack of composition.
Furthermore, the production of an effect by several vertical causes, such that each of them is the cause of another, is undeniable. In other words: neither the multiplicity of mediated effects, each of which is the effect of another, nor the multiplicity of mediated causes is contrary to the above principle.
On the other hand, all philosophers agree that an individual effect will have no more than one complete cause; in technical terms, the conjunction of several complete causes for a single effect is impossible, for if all these causes were effective, then necessarily numerous effects would be brought into existence by them, so the effect would not be one.
If some of these causes were not effective, this would be contrary to the principle of the mutual implication of cause and effect or the relative necessity (wujub bil-qiyas) of the effect with respect to its complete cause.
That over which differences arise regarding this principle is whether one kind of effect must always be produced by one kind of cause, or whether it is possible that some individual cases of a kind of effect may be produced by one kind of cause, while other individual cases of the same kind of effect are produced by another kind of cause.
It is here that most people who consider this principle to include unities of kind as well as individual unities, explicitly state that several kinds of causes may effect the appearance of a single type of effect, such as heat, which is sometimes the effect of the radiance of the sun, sometimes of the burning of fire, and sometimes the effect of motion and friction.
However, with regard to what was said about the principle of homogeneity, the existence of the effect may be produced only by a cause which possesses that same sinkh (root), an existential perfection at a higher level [than that exhibited by the effect]. An effect will never be produced by an existence-giving cause which lacks the sinkh (root) which is the perfection of the effect.
Therefore, in the case of an existence-giving cause and its effect it must be said that not only is it impossible for an individual effect to be produced by two or more individual existence-giving causes, but a single type of effect also cannot be brought into existence by two or more types of existence-giving causes.
But in the case of material or preparatory causes, since there is no rational proof for the quality of their homogeneity with their effects, it cannot be established that one kind of effect must have one kind of cause. It is rationally possible that several kinds of material or preparatory causes should have a single kind of effect, as the number of conditions and their determinations cannot be established by rational proof, and all of them depend on experience.