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Lesson Thirty-Four: The Causal Relation among Material Things

The Cause of Belief in the Causal Relation among Material Things

Sometimes it is said that the knowledge of the causal relation among all existents, including material existents, is an innate (fiṭrī ) knowledge with which the human intellect has been fashioned, and on the basis of which specific causes and effects are determined. However, as has been discussed in the lessons on epistemology, no acquired knowledge can be proven to be innate, and assuming that it occurs, there would be no guarantee of its correspondence with reality.

However, as has been mentioned in Lesson Twenty-Three, some knowledge is near to being self-evident (bidāhat ), and in a sense can be considered to be ‘innate’, such as knowledge of the existence of material realities, which really has its source in a hidden or semi-conscious reasoning. The knowledge of the existence of the causal relation and the dependence of some material existents on others is also of this sort.

The closer we get to the beginning of infancy, the more unconscious reasoning becomes, until it becomes similar to the instinctive perceptions of animals. To the extent that man’s consciousness develops, reasoning becomes more manifestly conscious, until it takes the form of logical reasoning. For example, when a child hears a sound simultaneously with the collision of two objects, he vaguely understands the dependence of the appearance of the noise on the collision. When he witnesses the lighting of a lamp along with the flipping of a switch, he understands there to be another dependence of the same sort. In brief, his soul becomes thus disposed to understand the existence of the causal relation among material phenomena. However, he is not able to understand this relation in the form of a logical proposition or to express it in exact terms. Eventually he develops sufficient powers of mental analysis to understand this subject in the form of a logical proposition, and to expound the hidden foundational reasoning in the form of a logical proof. Of course, it is possible that at the beginning of this process one will use a concept which is not sufficiently precise, or one will present an argument which from a logical point of view is fallacious. For example, one might speculate that everything depends upon something else, or that every existent appears in a specific time and place. However, these unfortunate generalizations and other inadequacies in the interpretation of percepts and reasonings, are effects of the weakness of the analytic powers of the mind, and to the extent that one develops and strengthens the above-mentioned powers by means of logical exercises and philosophical analysis one will make fewer such mistakes.

In any case, as we have explained repeatedly, the firmest foundation for belief in the existence of the causal relation is knowledge by presence. The discovery of instances of causes and effects within the self is considered to be the most sturdy basis for the abstraction of the universal concepts of cause and effect and prepares the ground for the conscious understanding of the principle of causation as a self-evident (badīhī ) proposition. However,

since material instances of cause and effect cannot be known through knowledge by presence, and on the other hand, as mentioned above, since it is unacceptable to consider the belief in the causal relation among material things to be innate, there is no alternative but to consider the source of such beliefs to lie in a kind of reasoning, which, at its inception was semi-conscious and spontaneous, and gradually takes the form of clear logical reasoning.

Since this belief is close to being self-evident it may be called, in a sense, innate. In order to evaluate this belief one must first state this proposition in an exact form, and then give a logical explanation of it.

An Evaluation of the Above-mentioned Belief

The causal relation among material things may be stated in several forms. One is: “Material existents are dependent upon one another.” This proposition, which is called ‘unquantified’ (muhmalah ) in logic, does not indicate the universality or particularity of this relation. That is, it does not mean that all material things have this relation with one another, nor that only some of them have such a relation. It is certain that there exists a causal relation among some of them, and really, it is evaluated as a particular affirmative proposition, the contradictory of a universal negative proposition, the absolute negation of causation among material things, which view is associated with the Ash‘arites.

The second form is: “All material existents have a causal relation with another material existent.” This means that no material existent is to be found which is neither a cause nor an effect of another material existent. This leaves open the possibility that one or more material existents are merely causes for some phenomena and that they themselves are not the effects of other material existents (although they may be the effects of supernatural causes), the possibility also is left open that they are merely effects of material causes, and that they themselves are not causes of other material phenomena.

The third form is: “Every material existent has a material cause,” and the fourth form is: “Every material existent is the cause of another material existent and is the effect of another material existent.” An implication of the third proposition is a backward stretching infinite regress of material causes. An implication of the fourth proposition is an infinite regress in both directions.

Among these propositions, the first is certain and close to being self-evident, and it is the one which may be called innate. However, regarding the other propositions, they have been more or less in dispute and subject to differences of opinion which are presented in detailed philosophical texts under various topics.

Just as the principle of the existence of material things is not self-evident and needs to be proven, the existence of the causal relation among material things is also not self-evident. The warrant for this belief is not at the same level as the belief in the universal principle of causation, in the form of a verity proposition (qaḍiyyah ḥaqīqiyyah ), nor is it on the level of the belief in the existence of the causal relation for the totality of existents, some of whose instances are known through knowledge by presence. Rather, its

logical warrant is at the level of speculative certainties (naẓariyyāt yaqīnī ), which on the one hand are based on the self-evident principle of causality, and on the other hand are based on empirical premises. That is, after the real existence of material existents is established, and idealistic doubts are refuted, then with the help of experiences which establish that some material phenomena do not occur without some others, it may be concluded that the causal relation in its general sense, that is, absolute dependency (not a dependency that is absolute), holds among material existents, and that the material existent, in addition to having a need for a creative cause at the core of its being, is also such that its changes and alterations depend on the fulfillment of various conditions which are provided by other material existents, conditions which, in reality, serve to prepare matter for the acquisition of new existential perfections, even if the previous perfection must then be abandoned.

The Way to the Knowledge of Material Causes

As was indicated, there are many ways with regard to the absolute knowledge of causes and effects, but the way to the knowledge of material causes and effects is limited to empirical proof, that is, proof in which empirical premises have also been employed.

It is sometimes imagined that the repeated observation of two successive phenomena is reason for the first phenomenon to be the cause of the second. That is, empirical premises are used for the establishment of the causation of one material existent for another, in the form: “This phenomenon repeatedly comes into existence following another phenomenon.” Then another premise must be added: “For every two existents which occur in this form, the first is the cause of the second.” The conclusion obtained is that in the case experienced, the first phenomenon is the cause of the second phenomenon. However, as has been shown time and time again, succession or simultaneity are more general than causation, and cannot be considered to be decisive reasons for causation, that is, the major premise of this syllogism is not certain, and therefore neither can its conclusion be certain.

Logicians, when discussing the validity of empirical propositions, have said that the mutual implication (talāzum ) of two phenomena, either constantly or in most cases, indicates the causal relation between them, for persistent or nearly persistent simultaneity cannot be accidental.

Regarding this statement it must be said that, first of all, this proposition implies that something accidental cannot be persistent or nearly persistent, or in technical terms, that compulsion (qaṣr ) which occurs persistently or nearly persistently is impossible. Secondly, it is nearly impossible to establish the persistent or nearly persistent mutual implication of two phenomena, and no experimenter can claim that he has subjected most occurrences of two phenomena to experiment.

Likewise, another principle is sometimes employed to complement this proof, that two similar things will have similar effects. (“Judgment regarding similar cases of what is permissible or impermissible is one.”) Therefore, regarding cases of experimentation, if one observes the occurrence of a phenomenon under certain conditions, one will know that in other conditions which are exactly the same, the above phenomenon will

also occur. In this way the causal relation between [the conditions and the phenomenon] is discovered. However, this principle is not of very much practical efficiency, for the establishment of the complete similarity of two circumstances is no easy task.

It thus seems that the only way to utilize experience in order to establish definitively the causal relation between two given phenomena is to control the conditions for the occurrence of one phenomenon and to observe which of the controlled elements and conditions when changed alters this phenomenon, and with the existence of which conditions the phenomenon remains the same. For example, if in the controlled environment of the laboratory one observes that only with the connection of two given wires, a light bulb is lit, and that it goes out when they are disconnected, one may conclude that the above connection is the condition for the appearance of light in the bulb (transforming the electrical energy into light). If the conditions are precisely controlled, the performance of an experiment a single time will be sufficient. However, since the precise control of the conditions is no easy task, in order to be sure, the experiment is often performed repeatedly.

However, at the same time, it is extremely difficult to establish that the effective cause of the appearance of a phenomenon is the very factors identified in the experimental environment and that no other unidentified and unperceived factor exists. Even more difficult than this is to establish that it is the only factor and is irreplaceable, for there is always the possibility that under other conditions the given phenomenon will occur by means of other factors. Newer and newer discoveries in physics and chemistry confirm this possibility. This is why empirical conclusions will never have the value of the self-evident, and basically cannot produce redoubled certainty (certain beliefs whose contrary is impossible). Hence, the achievements of the empirical sciences will never have the value of the conclusions of pure rational proofs.

We should note that the existence of the mentioned possibilities which prevent the acquisition of redoubled certainty in relation to the principles of the empirical sciences is of no harm for the certainty of the causal relation among material existents, for with simple experiments it can be established that by excluding one phenomenon, another phenomenon will be eliminated. This shows that the first phenomenon is a kind of incomplete cause of the second. For example, with the setting of the sun, the sky becomes dark; and with the absence of water, trees become dry. Thousands of other examples can be observed repeatedly in the daily lives of men. What is difficult is to determine precisely all the factors and conditions which have an effect on the occurrence of a material phenomenon. If one were able to precisely determine all of them, this would not imply a denial of the influence of a supernatural agent, for the performance of an experiment in the case of such an agent is not possible. The existence or nonexistence of a supernatural agent can only be established with pure rational proof.

Lesson Thirty-Five: The Dependence of the Effect on the Cause

The Mutual Implication of Cause and Effect

In consideration of the definitions of cause and effect it is easy to see that not only is the occurrence of the effect impossible without its internal causes (the parts that compose it), but it is impossible without the occurrence of any of the parts of the complete cause, for it is assumed that the existence of the effect is in need of all the parts of the complete cause, and to suppose that it could occur without one of them would mean that it was not in need of it. Of course, in cases where the cause is replaceable, the existence of any of its alternates would suffice, but the assumption of the existence of the effect without any of them is impossible. In cases in which it is imagined that an effect comes into existence without a cause (as in cases of miracles), what really happens is that an unusual, unknown cause replaces the usual and known cause.

On the other hand, in cases in which there is a complete cause, the existence of its effect will be necessitated, for the meaning of complete cause is that everything needed for the effect is satisfied, and the supposition that the effect does not occur would mean that its existence is in need of something else, which is contrary to the original supposition. The assumption that something prevents the occurrence of the effect signifies the absence of the completeness of the cause, for ‘the absence of an impediment’ is also a condition for the occurrence of the effect, and the assumption of the completeness of the cause includes this negative condition. That is, when we say that the complete cause of something has occurred, this means that in addition to the occurrence of the positive existing causes and conditions, an impediment to the occurrence of the effect does not exist.

Some scholastic theologians have imagined that this principle applies specifically to involuntary causes which do not act out of a will, and that in cases of free agents, however, after the occurrence of all the parts of the cause there is still room for the volition and choice of the agent. They fail to observe the fact that rational principles cannot be thus restricted, and that in cases of voluntary action, the will of the agent is one of the parts of the complete cause, and as long as there is no will to carry out the voluntary action, the complete cause is not realized, even if all the other conditions of existence and nonexistence should obtain.

The conclusion is that every cause, complete or incomplete, has relative necessity (wujūb bil-qiyās ) in relation to its effect, and similarly every effect has relative necessity in relation to its complete cause, and these two points may be together referred to as ‘the rule of mutual implication of cause and effect.’

The Simultaneity of Cause and Effect

From the principle of the mutual implication of cause and effect other principles may be derived, among which is the principle of the simultaneity of cause and effect, which may be described as follows. Whenever an effect

is a temporal existent and at least one of the parts of its complete cause is also temporal, the cause and effect will occur simultaneously, and the occurrence of the complete cause will have no temporal distance from the effect. For if it is supposed that some time, no matter how short, elapses after the occurrence of all the parts of the complete cause and the effect occurs after that, this would imply that the existence of the effect is not necessary at that very supposed time, while the implication of the relative necessity of the effect in relation to the complete cause is that the existence of the effect becomes necessary as soon as the cause is complete.

However, this principle does not apply to incomplete causes, for the existence of the effect will not be necessary with the existence of any of them. Rather, even if just one of the parts of the complete cause is absent, the existence of the effect will be impossible, for otherwise the effect would not need the said part.

However, if the cause and effect are immaterial, and neither of them is temporal, in that case their temporal simultaneity would be meaningless. The same goes for the case in which the effect is temporal but the cause is completely immaterial, for the meaning of temporal simultaneity is that two existents occur at the same time, while something completely immaterial does not occur in the temporal realm, and has no temporal relation to any existent. However, such an existent is existentially encompassing in relation to its own effect and present, and the absence of the effect from this cause would be impossible. This subject will become clearer by taking into account the relational character of the effect with regard to its creative cause.

On the other hand, the temporal priority of the effect to any cause, whether complete or incomplete, is impossible, for this would imply that the effect would not be in need of the above-mentioned cause at the moment it takes place, and that the existence of the cause in relation to the effect is not necessary. It is obvious that this principle is specific to temporal existents.

By taking this principle into account, it becomes completely clear that the interpretation of the causal relation as the succession of two phenomena is incorrect, for an implication of succession is the temporal priority of the.cause to the effect. Not only does this have no meaning for immaterial things and creative causes, but it is also impossible for complete causes that include non-temporal elements. The only case to which the principle of succession applies is that of incomplete temporal causes, for which their temporal priority to their effects is possible, such as the occurrence of a person prior to the performance of a task.

On the other hand, it has already been said that the regular succession of two phenomena is not specific to cause and effect, and many phenomena come into existence one after the other without there being any causal relation between them, such as day and night. So the relation between cases of causation and cases of succession is referred to in technical terms as one of ‘generality and specificity in some respects.’

Let it not be left unsaid that the simultaneity of two existents is not confined to causes and their effects. There are many phenomena that occur simultaneously without any causal relation between them. It is even possible

for two phenomena to be persistently simultaneous without any of them being the cause of the other. For example, if a cause brings about two effects, the given effects always come into existence together, while neither of them is the cause of the other. So, the relation between cases of causation and cases of simultaneity is also one of ‘generality and specificity in some respects,’ that is, in some cases there is both simultaneity and causation, such as the complete temporal cause and its effect; while in some other cases causality exists but simultaneity does not, such as immaterial causes and incomplete causes that exist before the occurrence of their effects. In some cases there is simultaneity without causality, such as the simultaneous appearance of light and heat in an electric lamp.

Therefore, the correct interpretation of causation is neither in terms of the succession of two phenomena nor in terms of the simultaneity of two phenomena. Succession and simultaneity cannot even be considered to be implications of cause and effect, nor can the interpretation of causation in terms of them be considered a kind of ‘specific necessity’ for neither of them is specific to cause and effect. Likewise, one cannot consider the interpretation of causation in terms of them to be a kind of ‘general necessity’, for neither of them is true of all cases of cause and effect.  Furthermore, it is basically incorrect to define something in terms of something more general, for such a definition in no way specifies the object defined.

The Persistence of the Effect is also in Need of a Cause

Another principle which can be derived from the mutual implication of cause and effect is that the complete cause must persist for the duration of the effect, for if the effect persists after the destruction of the complete cause, or even after the destruction of one of the parts of the complete cause, this would imply that the existence of the effect would not be in need of its cause during its persistence, while this need is an essential requirement of the existence of the effect of which it can never be divested.

This principle has long been a topic of discussion among philosophers and theologians. The philosophers have always emphasized that the persistence of an effect is also in need of a cause. They have reasoned that the criterion of the need for a cause by an effect is the effect’s whatish contingency, and the whatness of the effect can never be divested of this property. Therefore, it will always be in need of a cause.

The theologians, who for the most part consider the criterion of the need for a cause to be coming into existence (ḥudūth ), or contingency and coming into existence jointly, do not consider the persistence of an effect to be in need of a cause, and it is even reported that some of them held that if it were also possible for God, the Exalted, to perish, this would be of no harm to the existence of the world!! In order to support their position, they have resorted to cases of the persistence of effects after the destruction of their causes, such as the remaining alive of a child after the death of its father, or the remaining of a building after the death of its builder.

In response to them, the philosophers say that the only criterion of the need for a cause by an effect is contingency, not coming into existence and not a combination of contingency and coming into existence. In order to

establish this point, they set forth the following rational analysis: Coming into existence is an attribute of the existence of the effect, and from a rationally analytic point of view, this is posterior to its existence. Existence is subordinate to creation, and creation (ījād ) is posterior to necessity (wujūb ) and being made necessary (ījāb ). Being made necessary pertains to a thing which lacks existence, that is, which has contingent existence. This contingency is the very attribution which is abstracted from the whatness itself, for it is whatness which is equal with respect to existence and nonexistence, and does not have a preponderance for either of them. Hence, the only thing which can be the criterion for the need for a cause is this essential contingency itself, which is inseparable from whatness. For this reason the need of an effect will also be persistent, and the effect will never be without need for a cause.

However, this position, as was indicated earlier, is in conformity with the fundamentality of whatness, and with regard to the fundamentality of existence the criterion for the need for a cause must be sought in the existential characteristics of the effect, that is, as was stated by Ṣadr al-Muta’allihīn, the criterion for the need of an effect for a cause is essential poverty (faqr-e dhātī ) and dependence, in other words, the weakness of its existential level which is inseparable from it. With regard to the cases which the theologians used as evidence for the persisting of an effect after the destruction of its cause, it should be said that that which is destroyed or whose effects are terminated is not a real cause ( ḥaqīqī ), but merely a preparatory cause which in reality is merely an accidental cause for the mentioned effects.

This may be further explained as follows. The building which persists after the death of its builder has a set of real causes, including: the existence-giving cause, internal causes (matter and form), conditions for the existence of the building, such as the arrangement of the building materials in a specific shape and configuration, and a lack of impediments which could result in the separation of these materials. As long as this set of causes persists, the building will also persist. However, if the divine will is not in accord with the persistence of the building, or if the building materials, due to external factors, should decay, or if the conditions which are necessary for the maintenance of the shape of the building should change, then, without a doubt, the building will be ruined. The builder who puts together the building materials is really the preparatory cause for the appearance of this particular situation regarding the building materials. That which is a condition for the existence and persistence of the building is this very particular situation and not the person who by the movement of his hands causes the transference of the building materials and the appearance of the above-mentioned situation. The agency which is superficially related to the building is merely an accidental agency, and the builder’s real agency is with respect to the movement of his own hands, which obey his will. In the absence of the will, the movement would come to a standstill, and naturally, with his own destruction there would be no possibility of its continuation. Likewise, the existence of the child is an effect of its own real causes, which besides the existence-giving cause include specific organic materials with

special qualities which make the body disposed to possess a spirit, and as long as the necessary conditions for the possession of a spirit by the body persist, its life will continue. The father and mother have no role in the persistence of these causes, factors, and conditions. Even their agency in relation to the transference of the sperm and its establishment in the womb is also an accidental agency.

Likewise, the movement of a body, in reality, is the effect of some specific energy, which comes into existence in it, and as long as this agent persists, the motion will also continue. Relating the movement of the body to an external mover is like relating an effect to its preparatory agent which plays no other role than transferring the energy to the body. Moreover, it has become clear that preparatory agents of this kind, which are really accidental agents, are not considered to be parts of the complete cause, and the complete cause is composed of the existence-giving agent, internal causes, and conditions of existence and nonexistence.

Lesson Thirty-Six: The Relations of Cause and Effect

The Homogeneity (Sinkhiyyah) of Cause and Effect

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 more clear 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.

The Removal of a Doubt

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.

Unity of an Effect for Unity of a Cause

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 Ṣadr al-Muta’allihīn in his “Journey of the Soul” in theAsfār , 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’ (ṣudūr ) 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 onesinkh (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.

Unity of Cause for Unity of Effect

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 (wujūb bil-qiyās ) 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 samesinkh (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 thesinkh (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.