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The Theory of Necessity (Sadra’s Theory in the Interpretation of Causality and its Relation to Human Freedom)

Before explaining the theory of necessity, it is noteworthy that the reason beyond calling this theory "The Theory of Necessity" lies in the fact that according to this theory the relation between cause and effect is both the relation of existence and that of necessity.

The dispute between Muslim philosophers and theologians on all types of cause on one hand and between philosophers and modern usuliyyun on voluntary agent or cause on the other hand does not concern bringing of the effect into existence by the cause, but rather granting necessity to the effect by the cause. According to the theory of necessity, the effect not only depends on the cause for its existence, but also for its necessity.

Early theologians took the cause in a general sense and the mainstream of modern usuliyyun take the voluntary agent in a particular sense just as the originator of the effect and not as the necessitating.

To give a comprehensive account of "necessity" containing its philosophical grounds in Sadra’s view requires a long and broad discussion, which is beyond the scope of this short essay. Here we are concerned with three subjects that we will study in the following order:
Short explanation of "The Theory of Necessity" in Sadra’s thought

An account of the hypotheses of philosophical contradiction between this theory and the principle of free will
Method of philosophical solution of the above-mentioned contradiction according to Sadra and the theory of necessity.

1- Short Explanation of the Theory of Necessity

According to the theory of asalat al-wujud (principality of existence), natures (quiddities) are conventions of our mind and what is really there is just "being" or "existence". In other words, among all concepts and mental images, the only concept that can describe the external world and can genuinely represent the reality outside our mind is the concept of "being".

Therefore, the key to know the universal laws and rules that govern the universe is the universal principle of asalat al-wujud. The general structure of philosophical knowledge of the world is based on this principle, from which the universal philosophical laws governing the world have to be derived.

The most important philosophical principles of cosmology derived from asalat al-wujud are:

A- Graduation (hierarchical structure) of Being

According to asalat al-wujud, the differences that we understand among things in the world are all rooted in their "being" and can have no root other than the reality of ‘being’. Therefore, all things in the world differ in "being", just as they share ‘being’. The reality of being [in contrast to the concept of being] is a reality that admits differences and multiplicity of types and every type of being is a level of being which is different from other beings in intensity and weakness, and unlimitedness and limitedness.

Different types of being differ from each other in that one is weaker, that is, more dependent and more needy and the other is more intense, that is, more independent and less needy. The difference of being in degrees of dependence on and need for the other which is the same as the difference in weakness and intensity is the source for all differences and varieties in the world.

The peak and the most intense being is the self-independent being, which is absolutely free from need, that is, the eternal self-necessary being. The self-necessary being has no need for any condition and is the absolute being and enjoys the ultimate existential actuality. The self-necessary being is the originator of the hierarchy of being. All other levels of being are manifestations of self-necessary being, on whom they entirely depend.

Despite its total dependence on the self-necessary being, the first being created by the self-necessary being has no need to other levels of being and therefore in relation to other levels of being enjoys independence, freedom from need and absoluteness. Other levels of being depend for their existence on self-necessary being and on the first creature as well, since through it the grace of being extends to other levels. Thus, the highest being is the completely actual independent absolute self-necessary being and the lowest is the being that has nothing other than potentiality of being.
In his Mabda’ wa Ma‘ad, Mulla, Sadra says:

“And beings do not differ in their essence except in intensity and weakness, perfection and imperfection, priority and posteriority. Being accidentally differs because of those notions that are subordinate to them, i.e. their different natures”.

Also in the discussion on potentiality and actuality in his Al-Asfar al-Aqliyyah al-Arbi‘ah, Mulla Sadra says:

“Surely the thing, which is liable to movement, is potential either in this aspect or in all aspects, and the mover is actual either in this aspect or in all aspects. Inevitably, those aspects of actuality will end in something, which is actual in all aspects; otherwise it would lead to vicious circle or infinite regress. Similarly, those aspects of potentiality will end in something, which is potential in all aspects except in being potential, since it has this potentially in actuality and this is what make it distinguishable from absolute nothingness. So it is proved that there are two sides for the being: one side is the first real and the absolute being, May His name be glorified, and the other side is the materia prima. The former is absolutely good and the latter is bad and has nothing good except accidentally. It is accidentally good, because it is the potentiality for all beings, in contrast to nothingness, which is absolutely bad”.

B- Independent Being and Relational Being

According to what was said earlier, the difference among beings is the difference in levels and degrees of existence starting with the self-necessary being and ending with the potential being. Reflection on the reality of "being" leads to the conclusion that apart from self-necessary being which itself is "the reality of being" and the peak of the hierarchy of being, other levels of being have no reality other than belonging and relation to self-necessary being. Any thing apart from the divine essence is nothing other than relation and belonging to Him.

Therefore, the universe of being consists in an independent and self-necessary being; other levels of being are His manifestation and belongings. Manifestations and belonging of necessary being or levels of dependent beings have no being without relation to the necessary being. If someone thinks that in addition to the source of the being which is the self-necessary there are or may be other beings that have reality more than belonging and relation to self-necessary being he has made a mistake and has not understood the reality of being and asalat al-wujud.

The being which essentially and by itself deserves existence is the self-necessary being which is the reality of being itself. From this necessary being, another being emerges which is His amr (command) and is nothing other than relation to and dependence on him. This relational (dependent) and command-based being is just one, since it is originated by the Absolute One ("and our command is not but single"-the Qur’an) and since Divine grace is infinite and all are simply relation and belonging to the One Necessary being. Mulla Sadra says:

O you who are seeking for the truth! The truth has appeared from this account that you have heard: the reality of being because of its simplicity and having no nature, no constituent and no limiting part is the necessary being itself that deserves ultimate and infinite perfection, since every other level of being lower that than level in intensity is not absolute reality of being”1.

Elsewhere he says: “Therefore, the effect by itself, since it is effect, has no reality other than reliance and dependence and has no meaning other than being effect and subordinate, without having an essence subject to these meanings, as the absolutely originating cause has no essence and reality other than being the principle and source of everything and all relations and dependence go back to him.

So if it is proved that the chain of beings -including both causes and effects- originates from an essence which is a simple luminous primary existential reality free from multiplicity, deficiency, contingency, short coming and unclarity, free from anything accidental or additional to Him, internally or externally and it is also proved that He is gracious by Himself and luminous by His reality and illuminating heavens and earth by His entity and the source of the origin of the universe of creation and command by His existence, the conclusion is that all beings have the same origin and are of the same kind which is the reality and the rest is His affairs. He is the essence and the rest is His names and attributes. He is the principle and the rest is His states and affairs. He is the being and the rest is His aspects and features”.2

C- Cause and Effect

From what has been said before, the concepts of causation, cause and effect become clear. Cause is an independent being which has no need for its effect, originating and necessitating the effect. Effect is a totally dependent being, which is nothing other than relation to and dependence on its effect and has no identity other than this. Causality is not apart from the essence of the effect and the cause. The essence of cause in the context of influence and origination is its causality and the effect itself is nothing other than causality in the context of receptivity. In a mental analysis, there are three concepts:

1-the cause, i.e. the originator

2-the effect, i.e. the originated

3-causality, i.e. the origination.

These three concepts can only be separated by a mental assumption or metaphor. They are not separable from each other even in the mind and with an intellectual analysis, except in an intellectual metaphor.

Cause, causality and effect are interrelated concepts that are not detachable from each other neither in reality nor in our understanding. Mulla Sadra says:

The effect by itself is a simple thing like the cause by itself and that is when the attention is limited to them. When we abstract the cause from whatever does not bear on its causation and influence, that is, when the cause is considered as such and when we abstract the effect from whatever does not bear on its causedness it becomes clear and certain that what is called as effect has no reality other than the reality of its originating cause so the intellect cannot refer to the entity of effect disregarding the entity of it originator…

Therefore, the effect by itself has no reality in its causedness except that it is dependent and relational and has no meaning other than being an effect a-subordinate without having an essence exposed to those meanings, just as in the case of the absolute originating cause being principle, source, origin and followed is the same as its essence”.3

Causality in the way explained above implies certain principles and rules, whose denial would be equal to the denial of the principle of causality itself. The first principle implied by the principle of causality is the principle of necessitation of effect or the relation of necessity between the cause and effect. Mulla Sadra says:

Having proved that no contingent comes into existence without something making its existence outweighing its nothingness and does not become annihilated without something making its nothingness outweighing its existence, so both sides have to be preponderated by an external cause, now we say: that preponderator will not be preponderator unless its preponderance reaches the level of necessity.

Therefore, unlike what most theologians have thought if the preponderance caused by an external cause does not reach the level of necessity it will not be sufficient for the existence of the contingent, because as long as the contingent conveys both possibilities it will not exist. Is this not the case that if its existence is not made necessary by something else its both existence and non-existence would be possible, so no side is determined and to would still need something to preponderate either existence or non-existence.”4

In this way, Mulla Sadra takes the principle of necessitation of effect as a result of the principle of causality itself and its denial to be identical with the denial of causality, because the principle of causality is based on needs of the contingent for a cause that puts an end to the state of equality of both existence and non-existence which is implied by causedness. As long as the cause does not necessitate its effect, it has not removed the state of equality.

Principles such as impossibility of separation of the effect from its cause and necessity of resemblance of cause and its effect in their generic reality are some other important principles derived from the principle of causality.

On the basis of asalat al-wujud, to conclude the above-mentioned principles from the principle of causality is more obvious and more decisive. For example, to draw the necessary relation between cause and effect from the principle of causality on the basis of asalat al-wujud a little reflection is enough to understand the concept of causality and necessity of originating effect by cause.

According to asalat al-wujud necessity is an inevitable implication of ‘being’ and all its levels, states and belongings. The essence of the first cause and whatever is created by it is being and necessity. Dependence on the self-subsistent is the essence of effect and also causation, influence, generosity and graciousness of the first cause is its essence, so the necessity of the existence of the effect is the same as its essence on the one hand, and the same as the essence of the cause on the other hand.

According to this fact, cause necessarily and essentially requires creation of effect and effect also necessarily and essentially requires dependence on cause and creation by cause. Thus, the principle of necessity of creation of effect by cause is a necessary and inevitable result of the principle of causality.

Another important philosophical law, which is derived in the light of causality from asalat al-wujud, is the problem of criterion of need for a cause. This problem is one of the supreme problems discussed in Islamic philosophy and is exclusive to it. Muslim theologians take non-eternity (huduth) as the criterion of need for cause, that is, they believe the reason for having need for a cause is non-being and then coming to be. Since the existence is preceded by non-existence, there must be a cause that led to this transition from nothingness into being.

Muslim philosophers prior to Mulla Sadra developed strong arguments against the theory of theologians and proved that non-eternity cannot be the reason for need, because it is possible to suppose a being which is eternal and at the same time in need of a cause on which it eternally depends. Philosophers before Sadra held that the criterion is contingency.

In other words, the main reason for having need for a cause is the fact that the thing by itself possesses no necessity for existence and non-existence and has equal relation to both existence and non-existence. This logically results in the necessary relation of effect to cause, because as mentioned above as long as the main reason of need for cause is contingency (non-necessity of existence and non-necessity of non-existence), what the cause of existence has to grant the effect is necessity of existence and what the cause nothingness has to grant is the necessity of nothingness.

Mulla Sadra in his excellent studies viewed the theory of his predecessors imperfect and appropriate for the universe of natures. In his studies, he proved that when we consider the relation between nature of something and existence or non-existence the view of previous philosophers is true, because nature of a contingent being has equal relation to both existence and non-existence and none of them is necessary for it.

Therefore, to become existent or non-existent it needs a cause that grants necessity of existence or necessity of non-existence to it.

However, according to asalat al-wujud and subjectivity of nature, what is created by the cause is the existence of effect. Existence has no equal relation to existence and non-existence, so the view of previous philosophers cannot be true. Therefore, the criterion of need of being of effect for cause is not the equal relation of existence and non-existence to the existence of effect or contingency.

The criterion is existential poverty or in other words dependence or relationality of existence. If we reflect on the existence of effect we will find it dependent and subordinate. This dependence and non-self- subsistence have made the effect in need of the cause. Therefore, need for cause is the same as the essence of effect and identified with its existence.

As mentioned earlier, the essential dependence of effect on its cause results in the necessary relation between cause and effect. According to this philosophical analysis, the essence of effect is an inseparable result and outcome of the essence of cause and impossibility of separation of effect from cause is another expression of necessitation of effect by cause.

2- An Account of Hypothesis of Philosophical Contradiction between the Theory of Necessity and Free Will

Early theologians and modern usuliyyun who seriously oppose the theory of necessity or necessitation of effect by cause or in other words the necessary relation of cause and effect, take this theory in conflict with free will and believe that even if we accept its truth in respect to non-voluntary causes, it cannot be accepted in respect to voluntary causes, because voluntariness of an act in voluntary causes contradicts necessity of that act and since voluntariness of acts in voluntary causes is admitted necessity of effect in voluntary causes must be wrong.

To explain the alleged philosophical contradiction between the theory of necessity and freedom or free-will in the case of voluntary agents we will clarify the main point of contradiction analyzing briefly two sides of the alleged conflict:


If we limit the principle of causality to the ‘need of effect in its existence for a cause’ and consider the effect as something that depends in its existence on the originator there seems no contradiction between causality and free will. In the first sight it seems possible to have something dependent on something else without any necessary relation between them.

This means that cause would have equal relation to existence and non-existence of its effect and effect would remain contingent and unnecessary. This type of relation between voluntary cause and effect is in accordance with the viewpoint of early theologians and modern usuliyyun. In this way, there would be no contradiction between causality of a voluntary agent and his freedom and free will.

However, as we discussed earlier, causality in the way presented by philosophers cannot be limited to the existential relation between cause and effect. It rather involves necessary relation as well. Existence and necessity of the effect are not separable. Cause cannot bring the effect into existence without necessitating it; otherwise it would lead to groundless preponderance and we know that impossibility of such preponderance is the basis of the principle of causality.

The core of the alleged conflict between causality and free will is the very necessitation of effect by cause. It has been assumed that if the existence of effect is preceded by necessity of existence there would remain no place for free will. In other words, free will or freedom is only possible when the effect has the possibility of both being originated and not originated by the cause. Necessitation of effect is equal to determinism.

Free Will

There are three elements involved in every voluntary (free) act:
• Prerequisites of willing the act;

• Willing the act;

• The act itself.

There are two relations between these three: the relation between (a) and (b) and between (b) and (c).

It is usually assumed that after the completion of all factors bearing on the existence of a voluntary act its existence becomes necessary as soon as the agent wills it. Thus, there is a necessary relation between willing the act and act itself.

Not only there is no conflict among this necessary relation between act and will of the agent and free will, but also there can be no free will without this necessary relation. To suppose that there can be will of agent and all requisites without having the act would contradict the free will and power of the agent.

For the same reason, it seems that the dispute between philosophers and modern usuliyyun (and also some early theologians) mostly concerns the first relation, i.e. the relation between prerequisites of willing the act and willing the issuance of act from the voluntary agent and not the relation between act and the will. Modern usuliyyun and some early theologians believe that relation between willing the act in the voluntary agent and its prerequisites is necessary there would be no free will and it would result in absolute determinism.

In any case, the debate between philosophers and their opponents on the necessary relation of cause and effect can be conceived in both aspects of the relation of a voluntary act to its prerequisites, i.e. the relation of the essence of act and will of the agent and the relation of will of the agent and prerequisites of its existence.
Among modern usuliyyun, Mirza Na‘ini (d. 1355 A.H) distinguished four main elements in a voluntary act:

• Prerequisites of will;

• Will (iradah);

• Decision (ikhtiyar);

• Essence of the act.

He meant by ikhtiyar the instant movement of the soul towards the act (the embarking of the soul on the act) and took it as a result of iradah, will.

Mirza Na‘ini takes the first two elements to be involuntary subject to the necessary relation of cause and effect, but he takes the third element, i.e. ikhtiyar that sits in between will and the act to be outside the domain of cause-effect necessity. He takes this to be the key point in voluntariness of act.5

In any case, for Muslim philosophers, especially for Mulla Sadra, the relation of a voluntary act to its prerequisites (iradah or ikhtiyar) and the relation of iradah (will) to its prerequisites is a relation of necessity and the principle of necessary relation of cause and effect is exceptionalness. Mulla Sadra says:

The criterion for willingness is to have the will as the cause for the act or non-act. And surely a willing agent is the one that if he wills he acts and if he does not feel he does not act, even if the will [itself] is necessitated by itself or by the other or is impossible by itself or by the other6.

Modern usuliyyun believe that the relation between voluntary act and its prerequisites is by no means a necessary and determined one and that the cause-effect necessity does not include the relation between the voluntary act and its prerequisites. Therefore, even if all prerequisites of a voluntary act were available the act still would not be necessary to be issued by the voluntary agent and it still remains contingent. This contingency or the possibility of acting and not acting or the equal relations of the agent to act and non-act is the core of will and voluntariness in a voluntary agent. Na’ini says:

“If you say: is the fourth idea on which you built al-amr bayn al-amray (the state between two states) and the negation of determinism and made it something between the will and the movement of the muscles contingent or necessary? I would say: No doubt, it is created and contingent, but it is the ikhtiyar itself, an act of the soul and the soul itself bears on its existence, so there is no need for a necessitating cause whose effect is never detached from it, because causality of this type is only there for non-voluntary acts.7

Some modern usuliyyun have noticed a problem here and tried to solve it. The problem is that if after completion of all prerequisites of a voluntary act including the will itself the act still remains unnecessary it would imply denial of power and will of the agents since the will of the agent would have no role in the emergence of the act and origination of the act falls out of agent’s power. Therefore, if ikhtiyar is taken to mean contingency and unnecessity of existence and non-existence it would imply negation of ikhtiyar.

To respond to this problem usuliyyun have distinguished between two types of necessity:

(a) the necessity prior to ikhtiyar, i.e. the necessity which is source of decision or in other words necessity of cause of ikhtiyar

(b) necessity after ikhtiyar, i.e. the necessity whose source is ikhtiyar or in other words the necessary relation between ikhtiyar itself and its effect: the voluntary act. They maintain that the former is in conflict with ikhtiyar and they deny it, but not only do they accept the latter, but they also take it to be compulsory, because there will be no ikhtiyar without it and there is no conflict between necessity which is caused by ikhtiyar and the ikhtiyar itself.


3-Philosophical Solution of Contradiction between Necessary Causality and Free Will according to Sadra and the Theory of Necessity

The solution relies on three main points:

A- To distinguish between necessity and determinism and between contingency and free will. According to Sadra, critics of the theory of necessity have failed to distinguish between ikhtiyar and contingency or between determinism and necessity and therefore they have thought that necessary relation of cause and effect would lead to determinism, so to deny determinism which is against our conscience and rational arguments, one has to deny the theory of necessity. However, necessity does not imply determinism and has no conflict with ikhtiyar, just as contingency does not mean ikhtiyar and is not implied by voluntariness of the act.

Necessity and contingency are two mental concepts that are abstracted by mind from the relation between the thing and existence, while determinism and free will are two real qualities attributed to the act outside mind.

Acts of a voluntary agent are characterized as necessary whether or not they are voluntary; because if the voluntary agent is a self-necessary existent his acts also are necessary and if he is self-contingent he and his acts are necessary by the other. Therefore, voluntariness does not imply contingency, just as necessity does not imply determinism.

B- The reality of free will and freedom consists in choosing out of consent and not under an external force imposing an unpleasant choice. Accordingly, every act arising from agent’s consent that is not chosen because of an imposing external factor is a free and voluntary act. Therefore, the main criterion for voluntariness is not contingency; rather it is the consent of the agent and lack of an imposing external factor. Mulla Sadra says:

“When the source of originating something is knowledge and will of the agent, whether knowledge and will are the same or different and whether knowledge and will are the same as the essence of the agent in the case of God or different in other cases, the agent is voluntary and the act is issued from the agent because of his will, knowledge and consent. Such agent is not called by the public or by the elite "involuntary agent". Neither its act is said to be issued out of determinism, though it is necessarily issued from the agent out of his will and knowledge”.8

The criterion for qualifying a voluntary agent as a free agent is that whenever he wills he acts and whenever he does not will he does not act. According to this definition, it makes no difference whether the agent necessarily or unnecessarily wills, because truth of a conditional proposition is compatible with the necessity of the condition or the conditioned.

Therefore, although will of the agent is subject to the principle of necessary relation of cause and effect and its realization or non-realization is necessary, the agent is still voluntary and enjoys complete freedom.

Mulla Sadra rejects the theologians’ definition of the free agent as the one who may act or not. This definition implies the possibility of voluntary act. He says:

“There are two well-known definitions for power, al-qudrah: First, possibility of act and its opposite, i.e. non-act, and second a state for the agent in which he acts if he wills and does not act if he does not will. The first interpretation belongs to theologians and the second to philosophers.9

He also says:

The criterion for willingness is to have the will as the cause for the act or non-act. And surely a willing agent is the one that if he wills he acts and if he does not feel he does not act, even if the will [itself] is necessitated by itself or by the other or is impossible by itself or by the other.10

C- A voluntary act is the one whose existence derives from the free-will of the agent, but free-will itself is voluntary in essence, that is by definition. Voluntariness of free will is not separable from it, though the free will may be caused by causes, which are the origins of the necessity of its existence. In other words, the fact that ikhtiyar itself is governed by the principle of necessary relation of cause and effect and its existence is necessitated by its cause does not turn it into non-ikhtiyarIkhtiyar is ikhtiyar by definition, whatever its cause might be and however it is issued from its cause.

On the basis of the above three points, there is no conflict between free will and the principle of necessity. Although the act of the voluntary agent is subject to the principle of necessity and the will of the agent becomes necessary after the completion of perquisites, the act of the voluntary agent is free because it derives from his will.

  • 1. Mulla Sadra, Al-Asfar al-Aqliyyah al-Arbi‘ah, vol. 6, pp. 23,24.
  • 2. Mulla Sadra, Al-Asfar al-Aqliyyah al-Arbi‘ah, vol. 2, p. 300.
  • 3. Mulla Sadra, Al-Asfar al-Aqliyyah al-Arbi‘ah, vol. 2, pp.229-30.
  • 4. Mulla Sadra, Al-Asfar al-Aqliyyah al-Arbi‘ah, vol. 1, pp. 221,222.
  • 5. Mirza Na‘ini, Ajawad al-Taqrirat, p. 91.
  • 6. Mulla Sadra, Al-Asfar al-Aqliyyah al-Arbi‘ah, vol. 6, p. 319.
  • 7. Mirza Na‘ini, Ajawad al-Taqrirat, p. 91
  • 8. Mulla Sadra, Al-Asfar al-Aqliyyah al-Arbi‘ah, vol. 6, p. 332
  • 9. Mulla Sadra, Al-Asfar al-Aqliyyah al-Arbi‘ah, vol. 6, p. 307.
  • 10. Mulla Sadra, Al-Asfar al-Aqliyyah al-Arbi‘ah, vol. 6, p. 319.

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