Wajib bil-Ghayr

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Wajib bil-Ghayr

Necessary by the other
Term identification
other names	Necessary through another, Contingent necessary
European equivalent	Necessary by another, Contingent being
Field	Metaphysics, Ontology
History and etymology
Key philosophers	Ibn Sīnā (Avicenna), Suhrawardī, Mullā Ṣadrā
Proponents	Naṣīr al-Dīn al-Ṭūsī, ‘Allāmah Ṭabāṭabā’ī
First used by	Ibn Sīnā (Avicenna)
Etymology	From wujūb (necessity) and bil-ghayr (by/through the other), indicating that necessity derives from an external cause.
Content and definition
Related concepts	Wājib bil-dhāt (Necessary by itself), Mumkin bil-dhāt (Possible by itself), causality, ontological dependence, essential possibility
Opposites	Wājib bil-dhāt (Necessary by itself)
Prerequisites	Division of being into necessary and possible, essential possibility, theory of causality
Comparison and correspondence
Western counterpart	Contingent being, Necessary being through another (in some Scholastic metaphysics)

Wājib bil-Ghayr (Necessary by the other)

Wājib bil-Ghayr (Arabic: الواجب بالغير, Persian: واجب بالغیر), meaning "necessary by the other," is a foundational term in Islamic philosophy, particularly in ontology and causality. It denotes an entity whose existence is necessary not by virtue of its own essence, but due to an external factor (its efficient cause). This term stands in contrast to "Wājib bil-Dhāt" (Necessary by itself) and is primarily applied to contingent beings (mumkināt), which are possible in themselves but become necessary in external reality due to their dependence on a complete cause.

The key characteristics of the wājib bil-ghayr are: essential possibility (imkān dhātī), necessity of existence due to a cause, need for an other, composition of its reality (non-simplicity), the possibility of necessity being extrinsic to its quiddity, and its division into eternal (non-preceded by non-existence) and temporal (preceded by non-existence).

Semantics and Conceptual Analysis

Technical Meaning

Wājib bil-ghayr is an entity that, when considered by itself without any external factor, is neither necessary in existence nor necessary in non-existence (i.e., it is essentially possible). However, when its complete cause exists, its existence becomes necessary. In other words, necessity here accrues to the essence from an external source (the cause). Ibn Sīnā (Avicenna) states in Al-Ta‘līqāt: "It is in its essence possible in existence, and by its other, necessary in existence."

Similarly, in Sharḥ Ḥikmat al-Ishrāq (Shahrazūrī) it is stated: "The possible (mumkin) becomes necessary by that which necessitates its existence, and becomes impossible by the absence of that which necessitates its existence."

Etymology

It is called "necessary by the other" because its necessity derives from the other (the cause), and its essence alone does not entail existence. Its opposite is "necessary by itself" (wājib bil-dhāt), whose necessity comes from its own essence. Mulla Sadra affirms in his commentary on Al-Shifā’: "Everything whose existence is necessary by another is not necessary by its own essence."

Historical Development of Meaning

• Peripatetic (Mashshā’ī) (Ibn Sīnā, Al-Farabi): Wājib bil-ghayr is posited as the counterpart to wājib bil-dhāt in the division of being into necessary, possible, and impossible. Emphasis is placed on its being "possible in essence" (mumkin bil-dhāt), and that essential possibility never separates from it.
• Illuminationist (Ishrāqī) (Suhrawardī, Shahrazūrī): Within the light-based metaphysical system, wājib bil-ghayr is a light whose existence is received from another (the Light of Lights, Nūr al-Anwār), and is essentially poor and dependent. Suhrawardī writes in Majmū‘a Muṣannafāt: "Everything whose necessity of existence is attached to something other than its essence is possible in itself."
• Transcendent Theosophy (Ḥikmat al-Muta‘āliya) (Mulla Sadra): Considers wājib bil-ghayr as a deficient existence (wujūd nāqiṣ) in need of perfection (kamāl), analyzing it within the framework of the "Simple Reality is All Things" (basīṭ al-ḥaqīqa kull al-ashyā’) and the gradation of being (tashkīk al-wujūd). It also emphasizes its "essential possibility" and "composition of reality."
• Later Philosophy (‘Allāmah Ṭabāṭabā’ī): In Nihāyat al-Ḥikma, he reformulates wājib bil-ghayr based on "essential possibility" and "necessity due to a cause," and divides it into eternal (qadīm) and temporal (ḥādith) types.

Place in the Philosophical System

The term wājib bil-ghayr plays a crucial role in the following branches of philosophy:

• Ontology (Metaphysics): As one of the divisions of being (necessary, possible, impossible) and as the direct counterpart to the necessary-by-itself.
• Causality (‘illiyya): It demonstrates the need of the effect for its cause and explains how the effect's existence becomes necessary. In Al-Shifā’, it is stated: "Thus the effect, with respect to its essence, is possible."
• Theology (ilāhiyyāt bil-ma‘nā al-akhass): It is established that all contingent beings (both immaterial and material) are necessary-by-the-other, and only God is necessary-by-itself.
• Epistemology: God's knowledge of things other than Himself, through His knowledge of His essence and His causality, results in His knowledge of contingents (which are necessary-by-the-other). It is stated in Sharḥ Uṣūl al-Kāfī: "He, glorified, is the agent of all things by an will that returns to His knowledge of His essence, which entails knowledge of His other."
• Philosophy of Ethics and Free Will: It is argued that voluntary human actions are also necessary-by-the-other and ultimately terminate in the necessary-by-itself.

History and Development

Ibn Sīnā (Al-Shifā’, Al-Ta‘līqāt) was the first to provide a clear distinction between the necessary "by itself" and "by the other," emphasizing the essential possibility of the wājib bil-ghayr. In Al-Mubāḥathāt, he also discussed the difference between necessity and existence and the possibility of "necessity by a cause."

Suhrawardī (Majmū‘a Muṣannafāt, Ḥikmat al-Ishrāq) defined the wājib bil-ghayr within his light metaphysics as "a light that is in itself, for itself, but by another" and stressed its essential poverty.

Fakhr al-Dīn al-Rāzī (Al-Mabāḥith al-Mashriqiyya) accepted the division of the necessary into "by-itself" and "by-the-other" and, in his discussion on determinism and free will, considered human actions to be necessary-by-the-other.

Naṣīr al-Dīn al-Ṭūsī (Sharḥ al-Ishārāt wa al-Tanbīhāt) divided the necessary-by-the-other into two types: "not preceded by non-existence" (eternal) and "preceded by non-existence" (temporal).

Mulla Sadra (Al-Ḥikma al-Muta‘āliya, Mafātīḥ al-Ghayb) extensively analyzed the wājib bil-ghayr as a "deficient existence" (wujūd nāqiṣ), "in need of perfection" (muftaqir ilā kamāl), and "lacking simplicity" (faqid al-basāṭa).

‘Allāmah Ṭabāṭabā’ī (Badāyi‘ al-Ḥikma, Nihāyat al-Ḥikma) defined the wājib bil-ghayr as "that whose necessity depends on another" and "everything necessary by another is possible."

Main Definitions and Formulations

Based on the source priority system, the most important definitions are:

1. Peripatetic Definition (Ibn Sīnā, Al-Shifā’, vol. 1, p. 38): "That which, when considered by itself without its other, does not have necessary existence, is not necessary by its essence." And in Al-Ta‘līqāt (vol. 1, p. 175): "It is in its essence possible in existence, and by its other, necessary in existence."
2. Sadrian Definition (Al-Ḥikma al-Muta‘āliya, vol. 1, p. 83; Mafātīḥ al-Ghayb, vol. 1, p. 233): "The necessary-by-the-other is the deficient existence that is in need of perfection."
3. Illuminationist Definition (Majmū‘a Muṣannafāt Shaykh al-Ishrāq, vol. 2, pp. 27-28): "The possible (mumkin) becomes necessary by that which necessitates its existence, and becomes impossible by the condition of the absence of that which necessitates its existence."
4. Definition by Essential Possibility and Accidental Necessity (Nihāyat al-Ḥikma, vol. 1, p. 51): "Every necessary-by-the-other is possible" and "that whose necessity depends on another."
5. Al-Ṭūsī's Definition (Sharḥ al-Ishārāt, vol. 3, p. 76): Dividing the necessary-by-the-other into "not preceded by non-existence" (eternally necessary-by-the-other) and "preceded by non-existence" (necessary-by-the-other at some time).
6. Al-Rāzī's Definition (Al-Mabāḥith al-Mashriqiyya, vol. 1, p. 122): "Necessity by the other (wujūb bil-ghayr) is consequent upon the necessity of the cause; therefore, it is possible for it to be extrinsic to quiddity."

Divisions and Classifications

a) Division of wājib bil-ghayr by the Priority and Posteriority of Non-existence (Sharḥ al-Ishārāt (al-Ṭūsī), vol. 3, p. 76; Al-Ta‘līqāt (Ibn Sīnā), vol. 1, p. 175):

• Eternal Necessary-by-the-Other (non-preceded by non-existence): e.g., immaterial intellects which are eternal (azalī).
• Temporal Necessary-by-the-Other (preceded by non-existence): e.g., physical bodies and accidents which come into being.

b) Division by Mode of Existence (Ḥikmat al-Ishrāq (Mullā Ṣadrā's commentary), vol. 4, pp. 39-40):

• Existence for itself, but by another (wujūd li nafsihi bi ghayrihi): e.g., intellectual substances (immaterial beings) whose existence is for themselves but is caused by another.
• Existence for another (wujūd li ghayrihi): e.g., accidents which exist for (inhere in) a subject and are caused by another.

c) Division by Composition (Al-Shifā’, vol. 1, p. 47; Sharḥ wa Ta‘līqa Ṣadr al-Muta’allihīn, vol. 1, p. 178):

• The necessary-by-the-other is composite (not simple in reality), because "what belongs to it by itself is different from what belongs to it from its other."

d) Division by Quiddity (māhiyya) (Mafātīḥ al-Ghayb, vol. 1, p. 234; Al-Ḥikma al-Muta‘āliya, vol. 1, p. 158):

• Every necessary-by-the-other possesses a quiddity (unlike the necessary-by-itself).

Proofs and Arguments

1. Proof of Essential Possibility and Accidental Necessity

In Sharḥ wa Ta‘līqa Ṣadr al-Muta’allihīn (vol. 1, p. 146), it is argued: Any being whose existence is necessary due to another cannot be necessary by itself, nor can it be impossible by itself (since the two contradict). Therefore, it must be "possible in existence by itself" (mumkin al-wujūd li dhātihi).

2. Proof of the Impossibility of a Single Thing Being Necessary by Itself and by Another

In Sharḥ wa Ta‘līqa Ṣadr al-Muta’allihīn (vol. 1, p. 146): "It is impossible for a single thing to be necessary in existence by itself and by another." Because if we suppose the other is removed or its existence is not considered, either its necessity remains (in which case it is not necessary by the other) or it does not remain (in which case it is not necessary by itself).

3. Proof of the Priority of Essential Possibility over Accidental Necessity

In Majmū‘a Muṣannafāt Shaykh al-Ishrāq (vol. 1, p. 360): "What belongs to a thing from its essence is prior to what belongs to it from its other." Since the wājib bil-ghayr is possible in its essence and its necessity derives from another, essential possibility is prior to accidental necessity.

4. Proof of the Termination of All Wājib bil-Ghayr to a Wājib bil-Dhāt

In Al-Qabasāt (vol. 1, p. 407): "It is not possible for the necessity of existence of an effect to emanate from the very essence of its efficient cause, unless that efficient cause is a being that is necessary by itself (wājib bil-dhāt)." Therefore, the entire chain of beings necessary-by-the-other must ultimately terminate in a necessary-by-itself.

5. Proof of the Priority of Necessity over Existence (in essence, not in time)

In Sharḥ Ḥikmat al-Ishrāq (Quṭb, vol. 1, p. 174): "So its necessity precedes its existence in essence (bi al-dhāt), not in time. For just as it does not exist unless it is necessary by the other, similarly, it does not cease to exist unless it is impossible by the other." Thus, accidental necessity is a prerequisite for existence.

Different Views

Issue	Peripatetic (Ibn Sīnā)	Illuminationist (Suhrawardī)	Transcendent Theosophy (Mulla Sadra)	Theologians (Mutakallimūn) (Fakhr al-Dīn al-Rāzī)
Main definition	Possible in itself, necessary due to another	Light possible due to another	Deficient existence in need of perfection	That whose necessity depends on another
Relation to essential possibility	Essential possibility is concomitant with wājib bil-ghayr	Essential possibility is a condition for accidental necessity	Essential possibility never separates from the possible	(Accepts it)
Composition	Composite (not simple in reality)	Composite	Composite and needy of parts	(Not specified)
Quiddity (māhiyya)	Has a quiddity	Has a quiddity (limited light)	Has a quiddity (quiddity other than existence)	Has a quiddity
Divisions by eternity/temporality	Eternal (intellects) and temporal (bodies)	Eternal and temporal	Eternal and temporal (with difference in intensity of existence)	Eternal and temporal
Relation to the Wājib bil-Dhāt	Effect and dependent	Emanated and essentially poor	Manifestation (shā’n), effusion (rashḥa), and deficient manifestation	Effect and dependent
God’s knowledge of it	Through imprinted forms (ṣuwar murtasima)	Illuminationist presence (ḥuḍūr ishrāqī)	Enfolded (inṭiwā’) in self-knowledge	(Differing opinions)
Example	Intellect, soul, body	Intellectual light, psychic light, natural light	Intellects, souls, bodies (gradational modes of existence)	—

Objections and Criticisms

1. Objection: Redefining Wājib bil-Ghayr leads to a paradox with Wājib bil-Dhāt

In Majmū‘a Muṣannafāt Shaykh al-Ishrāq (vol. 1, p. 210), it is objected that the definition "that whose non-existence implies a contradiction" applies to the necessary-by-itself, not to the necessary-by-the-other. It is possible that the non-existence of a contingent being is impossible due to an extraneous factor, while that being itself is not necessary by itself. Response: That definition pertains specifically to the necessary-by-itself. The necessary-by-the-other is known through its essential possibility and its dependence on a cause.

2. Objection: The Necessity of an Infinite Regress or Circularity

If every necessary-by-the-other requires a cause, and that cause is also necessary-by-the-other, an infinite regress (tasalsul) would follow. Response of the Philosophers: The chain of beings necessary-by-the-other must terminate in a necessary-by-itself (the "proof of termination").

3. Objection: A Single Thing Being Both Necessary-by-Itself and Necessary-by-Another (Ibn Kamūna’s Challenge)

In Sharḥ al-Hidāya al-Athīriyya (vol. 1, p. 344), it is reported that Ibn Kamūna asked: What prevents one thing from being both necessary-by-itself and necessary-by-another? Response of Mulla Sadra: The proof for the impossibility of two necessary beings implies either essential possibility or contradiction.

4. Objection: Multiplicity in God’s Essence due to His Knowledge of Necessary-by-Other Beings

In Al-Mabāḥith al-Mashriqiyya (vol. 2, p. 472), it is argued that knowledge of many things (the beings necessary-by-the-other) would imply multiplicity in the essence of the knower (God). Response: Multiplicity in the concomitants (lawāzim) of the essence, not in the essence itself, has no proof of impossibility. Moreover, God’s knowledge of these beings is through His self-knowledge and causality, not through the impression of multiple forms.

5. Objection: The Impossibility of the Persistence of Necessity when the Cause is Removed

In Sharḥ Ḥikmat al-Ishrāq (Shahrazūrī, vol. 1, p. 80) and Sharḥ Ḥikmat al-Ishrāq (Quṭb, vol. 1, p. 77), it is emphasized that the necessary-by-the-other loses its necessity when its cause is removed, which contradicts the nature of necessary-by-itself. Response: This is a feature of the necessary-by-the-other, not a flaw in the argument.

Philosophical Implications and Consequences

1. Essential Possibility is Concomitant with Wājib bil-Ghayr': "Every being whose existence is necessary by another is possible in existence by itself." Essential possibility never separates from the necessary-by-the-other, even in its state of necessity.
2. The Reality of Wājib bil-Ghayr is Composite: "That which is necessary by another eternally is also not simple in reality." Thus, all contingent beings are composed of existence and quiddity (or matter and form).
3. All Beings Necessary-by-the-Other Terminate in a Necessary-by-Itself: The chain of causes and effects ends with the necessary-by-itself (God).
4. The Reality of Things is through an Other: "Thus, it (the contingent), in its own limit by itself, is false (bāṭil), and by its other, it is true (ḥaqq)." Contingents are in themselves perishable and false; their reality comes from the other (the necessary-by-itself).
5. The Necessity of the Possible Precedes its Existence (in essence, not in time): In Sharḥ Ḥikmat al-Ishrāq (Quṭb, vol. 1, p. 174): "So its necessity precedes its existence in essence (bi al-dhāt), not in time," because it does not exist unless it becomes necessary through the other.
6. God's Power Encompasses Voluntary Actions through the Category of Wājib bil-Ghayr: In Badāyi‘ al-Ḥikma (vol. 1, p. 167): "Voluntary action does not occur except as necessary by the other (wājib bil-ghayr), like all other effects." Since the necessary-by-the-other terminates in the necessary-by-itself, divine power encompasses voluntary actions as well.
7. The Extrinsicality of Necessity from Quiddity in the Wājib bil-Ghayr: Fakhr al-Dīn al-Rāzī states in Al-Mabāḥith al-Mashriqiyya (vol. 1, p. 122): "Necessity by the other (wujūb bil-ghayr) is consequent upon the necessity of the cause; therefore, it is possible for it to be extrinsic to quiddity."

Related Terms

Term	Opposite/Related	Explanation
Wājib bil-Dhāt	Opposite	Necessity derives from its own essence, not from another.
Mumkin bil-Dhāt	Related	Neither existence nor non-existence is necessary by its essence; the wājib bil-ghayr is mumkin bil-dhāt at the level of its essence.
Mumtani‘ bil-Ghayr	Opposite	A being whose non-existence is necessary due to another.
Ma‘lūl (Effect)	‘Illah (Cause)	The wājib bil-ghayr is precisely the effect relative to its complete cause.
Deficient Existence (wujūd nāqiṣ)	Pure Existence (wujūd ṣirf)	The existence of the wājib bil-ghayr requires a perfection (kamāl) to be complete.
Composite (murakkab)	Simple Reality (basīṭ al-ḥaqīqa)	The wājib bil-ghayr is composed of two principles (existence and quiddity, or matter and form).
Essential Poverty (faqr dhātī)	Essential Self-Sufficiency (ghinā dhātī)	The wājib bil-ghayr is essentially poor and dependent on another.
Essential Possibility (imkān dhātī)	Accidental Necessity (wujūb ‘araḍī)	Two concomitant descriptions of the wājib bil-ghayr: possibility in its essence, necessity from another.

Comparative Table of Views

Attribute / Ruling	Peripatetic (Ibn Sīnā)	Illuminationist (Suhrawardī)	Transcendent Theosophy (Mulla Sadra)
Definition	Possible in itself, necessary by another	Light possible due to another	Deficient existence in need of perfection
Quiddity	Has a quiddity (quiddity other than existence)	Has a quiddity (quiddity of a limited light)	Has a quiddity (quiddity other than existence)
Composition	Composite of existence and quiddity	Composite	Composite of existence and quiddity (or matter and form)
Essential Possibility	Concomitant with being necessary-by-the-other	Condition for accidental necessity	Never separates from it
Eternity and Temporality	Both types are possible (eternal and temporal)	Both types are possible	Both types are possible (with different intensities of existence)
Relation to the Necessary-by-Itself	Effect and dependent	Emanated and poor	Manifestation (shā’n), effusion (rashḥa), and deficient appearance
God’s Knowledge of It	Through imprinted forms (ṣuwar murtasima)	Illuminationist presence (ḥuḍūr ishrāqī)	Enfolded (inṭiwā’) in self-knowledge
Priority of Necessity over Existence	In essence (not in time)	In essence (not in time)	In essence (not in time)
Intellect, soul, body	Intellectual light, psychic light, natural light	Intellects, souls, bodies (gradational modes of existence)

Historical Timeline Diagram

Ibn Sīnā (Avicenna) (Al-Shifā’, Al-Ta‘līqāt)
   │
   ├──────────────────────┐
   │                      ▼
   │                 Fakhr al-Dīn al-Rāzī (Al-Mabāḥith al-Mashriqiyya)
   │                      │
   ▼                      ▼
Suhrawardī (Ḥikmat al-Ishrāq)  Naṣīr al-Dīn al-Ṭūsī (Sharḥ al-Ishārāt)
   │                      │
   └──────────┬───────────┘
              ▼
         Mullā Ṣadrā (Al-Ḥikma al-Muta‘āliya, Mafātīḥ al-Ghayb)
              │
              ▼
         ‘Allāmah Ṭabāṭabā’ī (Nihāyat al-Ḥikma, Badāyi‘ al-Ḥikma)

See Also

• Wajib al-Wujud
• Contingency (philosophy)
• Causality
• Mulla Sadra
• Avicenna
• Illuminationist philosophy
• Ontological dependence
• Essence–existence distinction