Can an Infinite God Be Opposed? Constructing the Argument from Mutual Hindrance (Tamānuʿ) in Muʿtazilī Theology

Abstract

In Islamic theology, the oneness of God is grounded in a conception of divinity that precludes attributing any partner to God or positing a second eternal being alongside Him and affirms His absolute power and infinite will. Accordingly, the Qurʾān states that “… Nor is there any god beside Him; if there were, each god would have taken his creation aside and tried to overcome the others.” (Q 23:91), thereby emphasizing the unrestricted and irresistible nature of God’s sovereignty. One of the principal rational arguments developed to support this Qurʾānic conception of divinity is the argument from mutual hindrance (burhān/dalīl al-tamānuʿ). Indeed, the argument from mutual hindrance is itself grounded in the infinitude of the divine will and the consequent claim that the existence of two deities possessing absolute and infinite wills is impossible. Although the Muʿtazila regarded divine oneness as one of the founding principles of their theological system, they were nevertheless criticized on the grounds that some of the doctrines they developed in accordance with the principles of divine oneness (tawḥīd) and justice (ʿadl) -such as the doctrine of aṣlaḥ (God’s being obligated to do what is best) and their recognition of the independent efficacy of human will and power over human acts in a manner that limits divine will and power- are incompatible with the conception of absolute and unlimited divinity and, more specifically, undermine the conception of God’s absolute and unlimited sovereignty upon which the argument from mutual hindrance is based. Accordingly, they have been accused of rendering it impossible to construct this argument consistently within their own theological system. Against this background, whether the theological principles adopted by the Muʿtazila permit a consistent construction of the argument from mutual hindrance is a fundamental question. This study examines this problem through the doctrines of an originated (ḥādith) will subsisting in no substrate (lā fī maḥall), the theory of motive (dāʿī), the principle of God’s being powerful by virtue of Himself (qādir li-dhātihī), and the Muʿtazilī conception of the evidential value of possibility (imkān). Employing a comparative textual analysis, the study first identifies the criticisms directed by Sunnī theologians against the Muʿtazila and the reasoning underlying these criticisms. Then it analyzes the solutions developed by Muʿtazilī theologians to each of these problems. It argues that these issues were not merely criticisms advanced by Sunnī theologians, but were also recognized by Muʿtazilī theologians themselves, who developed different solutions within the framework of their own theological principles. In particular, the study demonstrates that the Bahshamī tradition sought to construct the argument from mutual hindrance in a manner consistent with the fundamental principles of Muʿtazilī theology.

1. Introduction

The demonstration of the oneness of God (tawḥīd) is one of the central concerns of Islamic theology (kalām). The Qurʾān’s emphasis on the absolute oneness of God, particularly in its address to the pagan Arabs, and its rejection of the existence of multiple deities provided an important basis for Muslim theologians to establish divine oneness through rational argumentation. Together with the debates conducted by Muslim theologians with the Dualists (Thanawiyya) and other dualistic belief systems, this issue developed into a more systematic theological problem. Among the arguments developed for this purpose, the argument from mutual hindrance (burhān/dalīl al-tamānuʿ) was systematically formulated on the basis of the Qurʾānic verse, “Had there been gods in the heavens and the earth other than God, both would surely have fallen into disorder.” (Q 21:22) and came to be regarded as one of the most significant rational proofs for the oneness of God within the kalām tradition.1

Prevention (manʿ) and mutual hindrance (tamānuʿ) are two interrelated concepts that express the relation of hindrance between two capable beings. Prevention (manʿ) refers to one of the two capable beings hindering the other from attaining what it wills, that is, preventing the occurrence of its object of will. Mutual hindrance (tamānuʿ), by contrast, refers to such hindrance becoming reciprocal; in other words, each of the two capable beings hinders the other from attaining what it wills (Mānkdīm Shashdīw 1996, p. 279; al-Muḥallī n.d., fol. 90b). Accordingly, the argument from mutual hindrance establishes the oneness of God on the basis of the consequences that would follow, with regard to the agents’ being capable, if two divine agents were assumed to exist and to will contrary acts. The theological significance of tamānuʿ, however, is not limited to demonstrating the numerical oneness of God. The argument also establishes a direct relationship between divine oneness and the unrestrictedness of the power, will, and agency entailed by divinity. A being whose agency can be hindered or limited by another agent cannot be said to possess absolute and unlimited power. From the perspective of divine infinity, therefore, the impossibility of a second deity is directly connected to the question of whether two divine agents could simultaneously possess equally unlimited power and will. In this respect, the argument from mutual hindrance establishes the necessary relationship between divine oneness and absolute and unlimited divine agency.

In the Muʿtazila, a rationalist school of kalām centered on the principles of divine unity (tawḥīd) and justice (ʿadl), the argument from mutual hindrance (tamānuʿ), which establishes the oneness of God on the basis of the unlimitedness of divine will and power, is constructed upon a set of interrelated principles. Indeed, al-Qāḍī ʿAbd al-Jabbār (d. 415/1025), one of the leading theologians of the Basran Muʿtazila, grounds the argument from mutual hindrance in al-Mughnī (The Sufficing Book) on a number of principles, each of which he substantiates in detail, and sets them out as follows: P1. An eternal being is eternal by virtue of its essence, and any being that shares with it the attribute of eternity must also share its other essential attributes. P2. A single object of power (maqdūr) cannot pertain to two capable beings. P3. The objects of power of a being capable by virtue of its essence (qādir li-dhātihī) cannot be finite. P4. The finitude of the objects of power entails that the agent is capable by means of a power (qādir bi-qudra). P5. An agent capable by means of a power can be capable through that power only if the power inheres in it. P6. The foregoing division is exhaustive; one of these possibilities must obtain with respect to the two capable beings, and this division leads to the conclusion that there can be no second eternal being. The division in question comprises three possibilities when the two capable beings will contrary acts: either the objects of both wills occur, neither occurs, or only one of them occurs (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, pp. 275–76).

The Zaydī-Muʿtazilī theologian Mānkdīm Shashdīw (d. 425/1034), one of al-Qāḍī ʿAbd al-Jabbār’s students, likewise explicitly states in his Taʿlīq ʿalā Sharḥ al-Uṣūl al-khamsa (Notes on the Commentary on the Five Principles) that the argument from mutual hindrance is constructed upon a number of principles, which he sets out as follows: P1. An eternal being is eternal by virtue of its essence. P2. Sharing essential attributes entails similarity and the sharing of other attributes. P3. Mutual hindrance can occur between two capable beings. P4. When the motive (dāʿī) of one who is capable of a thing is directed toward an act, the act must occur; such that, if it does not occur, the agent ceases to be capable. P5. One who is capable of a thing must also be capable of its opposite, if that thing has an opposite. P6. One whose object of will does not occur is hindered (mamnūʿ), and its objects of power are finite. P7. One whose objects of power are finite must be capable by means of a power. P8. One who is capable by means of a power must be a body. P9. The creator of the world cannot be a body (Mānkdīm Shashdīw 1996, pp. 278–79). Although the principles upon which the argument from mutual hindrance is based largely overlap in the two works, there are some differences in their number, scope, and formulation as independent principles. Whereas al-Mughnī gives particular prominence to the impossibility of a single object of power (maqdūr) pertaining to two capable beings and to the three possibilities that arise in a case of mutual hindrance, Sharḥ al-Uṣūl al-khamsa formulates some of the intermediate stages of the argument separately as independent principles.

Each of these principles is grounded in the Muʿtazilī theologians’ more general commitments concerning essential attributes, being capable, and the relationship between a capable being and its object of power (maqdūr). The claim that an eternal being is eternal by virtue of its essence and that sharing in eternity entails sharing in the other essential attributes is explained by the principle concerning the sharing of an essential attribute: two beings that share an essential attribute are, in this respect, similar to one another (mithl). If one of two similar beings possesses an attribute by virtue of its essence, the other must possess the same attribute as well. Otherwise, the two beings would be regarded as similar insofar as they share the same essential attribute, while differing with respect to the essential attributes entailed by that attribute. Accordingly, the supposition of a second eternal being alongside God entails that it too, like God, must be capable by virtue of its essence (qādir li-dhātihī) (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, p. 252; Ibn Mattawayh 1965, vol. 1, pp. 215–16; Ibn al-Malāḥimī 2012, p. 559). The principle that a single object of power cannot pertain to two capable beings is established on the basis of the impossible consequence that would follow from the same thing being brought about by two distinct capable beings. If two capable beings were capable of the same object of power, then, when that object occurs, it would have to count as the act of both. For what makes an act belong to its agent is the occurrence of the act together with the agent’s being capable of it. Accordingly, if one of the two capable beings brings about the object of power while the other does not, the same thing would have to be both brought about and not brought about. This is impossible, since it would mean that the same thing is both existent and nonexistent at the same time (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, pp. 254–55, 259–61). Al-Qāḍī further supports this principle by reference to motives (dāʿīs). The occurrence of an act in accordance with the motives of a capable being indicates that the act belongs to it. Therefore, if the motive of one of the two capable beings requires the act to occur, while that of the other requires it not to occur, attributing the act to both would contradict what their respective motives indicate (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, pp. 261–63). The claim that the objects of power of a being capable by virtue of its essence (qādir li-dhātihī) cannot be finite is explained by the fact that its being capable cannot be restricted to a determinate number of objects of power. For if it is assumed to be capable of a determinate number of objects of power, it must also be possible for it to be capable of more than that number. Therefore, a being capable by virtue of its essence must be capable of everything that can possibly be an object of its power (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, p. 277). The principle that one who is capable of a thing must also be capable of its opposite is based on the assumption that being capable entails the ability to perform contrary acts of the same kind. It is therefore possible for one of two capable beings to be directed toward an act and the other toward its opposite. The possibility of mutual hindrance (tamānuʿ) between two capable beings ultimately rests on this possibility (Ibn Mattawayh 1965, vol. 1, p. 216; Mānkdīm Shashdīw 1996, pp. 278–79). The principle concerning motive (dāʿī), in turn, is based on the view that, when a motive directing a capable being toward an act is present and there is nothing preventing the act from occurring, its failure to occur is incompatible with that being’s being capable (Mānkdīm Shashdīw 1996, p. 279).

Within the framework of these principles and the explanations concerning them, the argument from mutual hindrance is constructed by supposing the existence of a second eternal being. Since the second eternal being shares eternity with God, it must also share His other essential attributes and must therefore be regarded as capable by virtue of its essence (qādir li-dhātihī). Since each of the two beings capable by virtue of its essence is capable of a thing and its opposite, mutual hindrance (tamānuʿ) between them is possible. Accordingly, if one of them wills the motion of a body while the other wills the rest of the same body, three possibilities arise: either the acts willed by both occur, neither of the willed acts occurs, or only one of them occurs. The first possibility is impossible, since it entails the simultaneous occurrence of two contraries, such as motion and rest. In the second possibility, the failure of the acts willed by both to occur indicates that each hinders the other and, consequently, that the objects of power of both are finite. This is incompatible with the principle that the objects of power of an eternal being capable by virtue of its essence (qādir li-dhātihī) cannot be finite. In the third possibility, the one whose willed act occurs must be more capable than the other. This indicates that the objects of power of the latter are finite and, consequently, that it is capable not by virtue of its essence but by means of a power inhering in it. Being capable by means of a power, however, entails that it is a body and temporally originated. Thus, since the supposition of a second eternal being leads either to the conjunction of two contraries, to the finitude of the objects of power of an eternal being, or to the conclusion that the second eternal being is temporally originated, all three possibilities are invalid (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, p. 275; Mānkdīm Shashdīw 1996, p. 278).

As is evident from the available sources, the argument from mutual hindrance formulated above was one of the arguments employed in the Muʿtazilī kalām tradition from an early period to demonstrate divine oneness (tawḥīd). Indeed, al-Qāḍī ʿAbd al-Jabbār introduces the argument as “one of the arguments of our masters for the proposition that God, exalted and mighty, has no second” (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, p. 275), indicating that tamānuʿ was grounded in a Muʿtazilī tradition predating him. Moreover, al-Qāḍī ʿAbd al-Jabbār’s presentation, in the context of certain objections, of the views and responses of earlier Muʿtazilī theologians shows that tamānuʿ was not merely transmitted as an argument but also rested on a body of debate that had already developed in an earlier period. This is further supported by al-Qāḍī ʿAbd al-Jabbār’s reference to an independent work of his devoted specifically to the subject, entitled Kitāb al-Manʿ wa-l-tamānuʿ (The Book of Prevention and Mutual Hindrance)2 (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, p. 302), which further suggests that manʿ and tamānuʿ were treated as a distinct subject within the Muʿtazilī tradition. The continued systematic treatment of the argument from mutual hindrance in Muʿtazilī texts after al-Qāḍī ʿAbd al-Jabbār further confirms that the argument retained its place in the Muʿtazilī literature devoted to demonstrating the oneness of God (Mānkdīm Shashdīw 1996, pp. 277–83; al-Buṭḥānī 2011, pp. 120–21).

Muʿtazilī theologians did not merely employ the argument from mutual hindrance to demonstrate the oneness of God; they also addressed how the argument could be established within the framework of their own theological principles. Among the extant Muʿtazilī literature, al-Qāḍī ʿAbd al-Jabbār provides the most extensive treatment of these discussions. In al-Mughnī, in addition to presenting the basic form of the argument, he discusses in detail various problems associated with it (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, pp. 275–302). Nevertheless, the problems arising from the construction of the argument from mutual hindrance on the basis of Muʿtazilī theological principles, as well as the solutions developed by Muʿtazilī theologians to address these problems, have yet to receive comprehensive examination. This study examines which fundamental Muʿtazilī doctrines pose problems for the construction of the argument from mutual hindrance, the nature of these problems, and the solutions and responses developed by Muʿtazilī theologians to overcome them.

2. Problems Concerning the Muʿtazilī Formulation of the Argument from Mutual Hindrance

Whether the argument from mutual hindrance could be consistently constructed on the basis of Muʿtazilī theological principles was discussed within Muʿtazilī kalām in the context of the formulation of the argument, while in other theological traditions it emerged as a criticism directed against the Muʿtazila. Al-Qāḍī ʿAbd al-Jabbār’s presentation of various objections and discussion of the different responses given to them show that the problems concerning the construction of the argument were examined in detail within the Muʿtazilī tradition. In this context, theologians belonging to the Bahshamiyya, a school within the Basran Muʿtazila that developed around the teachings of Abū Hāshim al-Jubbāʾī (d. 321/933), one of the leading theologians of the Basran Muʿtazila, sought to establish the argument from mutual hindrance in accordance with their own theological principles.

The problems discussed within the Muʿtazila became, outside the school, the subject of a broader criticism that the argument from mutual hindrance could not be constructed on the basis of Muʿtazilī principles. In the Māturīdī tradition, one of the clearest expressions of this criticism is found in Tabṣirat al-adilla (The Demonstration of the Proofs) by Abū al-Muʿīn al-Nasafī (d. 508/1115), one of the tradition’s leading theologians. Al-Nasafī states that “this argument cannot be soundly established on the principles of the Muʿtazila” (wa-hādhihi l-dalāla lā tastaqīm ʿalā uṣūl al-Muʿtazila), thereby maintaining that the argument from mutual hindrance cannot be constructed within the framework of the Muʿtazila’s own principles. According to al-Nasafī’s account, after Abū Hāshim al-Jubbāʾī assumed the leadership of the Muʿtazila, he came to the conclusion that the school’s earlier theologians had failed to establish the oneness of God rationally in accordance with their own methods. He therefore maintained that the oneness of God could be known not through reason but only through transmitted proofs, and accordingly rejected the rational proofs of divine oneness, including the argument from mutual hindrance. Al-Nasafī further reports that Abū Hāshim maintained that, when the issue is considered solely from the standpoint of reason, reason does not establish the necessity of a single deity but instead allows for the possibility of two or more deities (al-Nasafī 1990, vol. 1, pp. 84–86; Direk 2021, pp. 85–86). Al-Nasafī also grounds his criticism that the argument from mutual hindrance cannot be constructed within the framework of Muʿtazilī principles in the Muʿtazila’s views concerning human acts, will, and power. According to him, the decisive role that the Muʿtazila assigns to human will and power in human acts restricts the scope of divine will and power and ultimately renders them ineffective in the face of human will. Al-Nasafī thus maintains that there is an incompatibility between the Muʿtazila’s commitments concerning will and power and the principles underlying the argument from mutual hindrance. In this respect, al-Nasafī’s criticism is also directly related to the question of divine infinity, since any limitation imposed on divine will and power is incompatible with their unlimited nature.

In the Ashʿarī tradition, one of the major schools of Sunnī kalām, which developed in critical engagement with Muʿtazilī thought, one of the most comprehensive critiques of the Muʿtazila in the context of the argument from mutual hindrance is found in al-Shāmil (The Comprehensive [Book]) by Imām al-Ḥaramayn al-Juwaynī (d. 478/1085), one of the school’s leading theologians (al-Juwaynī 1969, pp. 368–82). Al-Juwaynī identifies eight principles that he considers necessary for the construction of the argument from mutual hindrance3 and then examines whether these principles can be reconciled with Muʿtazilī theological commitments. In his view, the argument cannot be consistently constructed on the basis of the school’s own premises. According to al-Juwaynī’s account, later Muʿtazilī scholars recognized that the rational arguments for the oneness of God constructed on the basis of their own principles led to certain inconsistencies and could not be established in a manner consistent with the school’s doctrines. As a result, they maintained that there was no rational argument demonstrating the oneness of God and that it could be known only through revelation. Al-Juwaynī then presents al-Bāqillānī’s (d. 403/1013) assessment of the same issue, one of the leading representatives of early Ashʿarī kalām. According to al-Bāqillānī, one of the inconsistencies in Muʿtazilī doctrine lies in the fact that, while the Muʿtazila accord a broad role to rational argumentation in such matters as the vision of God (ruʾyat Allāh), the creation of human acts (khalq al-aʿmāl), guidance and misguidance (al-hidāya wa-l-ḍalāla), and the knowledge of the fundamental principles of religion, they do not accept that the oneness of God can be demonstrated by reason. According to al-Bāqillānī’s account, the Muʿtazila maintained that the oneness of God could be known only through revelation and that, in the absence of revelation, the existence of more than one deity could be regarded as rationally possible (al-Juwaynī 1969, p. 394).

These accounts show that the problems concerning whether the argument from mutual hindrance can be reconciled with Muʿtazilī theological principles were, on the one hand, discussed within Muʿtazilī kalām itself and, on the other, became the subject of criticisms directed against the Muʿtazila by theologians outside the school. The central question to be answered, then, is which Muʿtazilī doctrines gave rise to these problems, what kinds of difficulties they posed for the consistent construction of the argument from mutual hindrance, and whether these difficulties could be resolved within the framework of the Muʿtazila’s own theological principles.

3. Muʿtazilī Principles That Pose Problems for the Construction of the Argument from Mutual Hindrance

The initial Muʿtazilī doctrine that poses a challenge to the formulation of the argument from mutual hindrance is the Basran Muʿtazila’s perspective that God wills through a temporally originated (ḥādith) will subsisting in no substrate (lā fī maḥall). As will be discussed in detail below, this doctrine raises the problem of how two independent wills can exist in two eternal beings and how mutual hindrance can be conceived between them. The second Muʿtazilī doctrine is the approach that explains the origination of actions within the framework of the theory of motive (dāʿī) and deterrent (ṣārif). The crux of the issue here is how the motives of two eternal beings who are omniscient and wise by virtue of their essences (li-dhātihī) could differ and, consequently, how a conflict that would serve as the basis for a rational inference could be conceived between them. The third Muʿtazilī doctrine is the view that God is omnipotent not by means of a power, but by virtue of His essence. If the existence of a second eternal being besides God is conceived, it would necessarily have to be omnipotent by virtue of its essence as well. In this case, a fundamental issue to be explicated is how two eternal beings, omnipotent by virtue of their essences, could possess different objects of power, and how mutual hindrance could be conceptualized with respect to the same object of power. The fourth doctrine is the Muʿtazilī approach to the indication of possibility (imkān). The problem this approach presents for the argument from mutual hindrance is that the Muʿtazilīs adopt different approaches to indicating possibility regarding God’s ability to perform evil acts (qabāʾiḥ) and the possibility of mutual hindrance between two eternal beings. The Muʿtazilīs posit that the notion of God’s ability to perform evil acts merely as a possibility does not signify any inherent deficiency on the part of the divine. Conversely, they interpret the conception of mutual hindrance between two eternal beings at the level of possibility as an indication of the impotence of the hindered being. Although these four problems arise from different Muʿtazilī doctrines, they all bear on the question of divine infinity insofar as they concern, in different ways, whether divine will and power can be conceived as genuinely unrestricted. At this stage, each of these four issues will be examined more closely in the context of the argument from mutual hindrance, as problems addressed in Muʿtazilī texts and as criticisms directed against the Muʿtazila in Sunnī theological works.

3.1. Temporally Originated Will Subsisting in No Substrate and Mutual Hindrance

Although early Muʿtazilī theologians held divergent views regarding the divine will (al-Kaʿbī 2020, pp. 255–57), the Basran Muʿtazila in particular affirmed both the divine will and God’s being one who wills by virtue of that will (Peters 1976, pp. 273–76; Koloğlu 2017, pp. 251–56; Vishanoff 2025, p. 14). However, the Basran Muʿtazila, in accordance with the principles of divine unity (tawḥīd) and justice (ʿadl), held that God can be willing (murīd) neither by virtue of His essence nor by means of an eternal will. This is due to the fact that affirming that God is willing by His essence would require that He wills everything, both good (ḥasan) and evil (qabīḥ), which would conflict with the principle of justice. Similarly, affirming that He is willing by means of an eternal will would necessitate the existence of an eternal entity other than His essence, thereby violating the principle of divine unity (Mānkdīm Shashdīw 1996, pp. 440–47). Instead, the assertion was made that God is willing by means of an originated (ḥādith) will subsisting in no substrate (al-Qāḍī ʿAbd al-Jabbār 1962b, vol. 6, pt. 2, p. 149). The Basran Muʿtazilī doctrine of an originated will subsisting in no substrate gave rise to several problems concerning the distinction between substance and accident, the definition and ontological status of accidents, and, in particular, the theory of maʿnā-based attributes grounded in the causal relationship between cause and effect (Aktaş 2025, pp. 128–31). It has also been asserted that this doctrine renders the argument from mutual hindrance, which is posited as evidence for the oneness of God, impossible to construct. As posited by this objection, if the divine will is conceived as an originated will subsisting in no substrate, the prospect of mutual hindrance between two eternal beings becomes unthinkable. This is because, once the will is assumed to exist without subsisting in any substrate, both eternal beings would necessarily have to be willing by means of the same single will. For there is no basis for preferring that an originated will subsisting in no substrate be attributed to one of the two hypothetical eternal beings rather than to the other, thereby rendering it one who wills (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, p. 284; al-Sarakhsī 2026, vol. 2, p. 191; al-Juwaynī 1969, pp. 358–59; Mānkdīm Shashdīw 1996, p. 282; al-Farrazāzī n.d., fol. 98b). Given that the conception of a temporally originated will subsisting in no substrate leads to the conclusion that two eternal beings would be willing by means of the same single will, how can it be conceived that they could will different things and that a conflict could arise between them? This problem also bears on the infinitude of divine will, for if two eternal beings could possess equally unlimited wills, it would have to be explained how their wills could differ in their objects and thus come into conflict.

At a more fundamental level, this objection is rooted in a principle that recurs throughout the Muʿtazilī literature in discussions of the theory of attributes grounded in the presence of an accident. According to the Bahshamī theologians, who upheld the theory of states (aḥwāl), the qualities produced in bodies by accidents (aʿrāḍ) designated as cause (ʿilla) (al-Jishumī 2021, vol. 4, p. 694) belong to the category of attributes grounded in the presence of an accident. It is the position of the Bahshamīs that the capacity of a cause or an accident to necessitate a particular attribute in a specific body can be explained through the principle of particularization (ikhtiṣāṣ). In the context of accidents, the concept of particularization, which denotes the inherence (ḥulūl) of an accident in a specific substrate, is employed by the Bahshamī theologians within the framework of the view that a cause lacking a relation of particularization or inherence to a specific entity has no basis for necessitating an attribute in that entity rather than in another. For instance, the accident of motion necessitates the attribute of being in motion in substance y rather than in substance x because it inheres in substance y. In other words, the proposition “substance y is in motion” means that “substance y is in motion because the accident of motion inheres in it”. Therefore, so long as an accident does not inhere in its substrate, it cannot necessitate a state (ḥāl) or an attribute in that substrate. Indeed, al-Qāḍī ʿAbd al-Jabbār states that if the condition of particularization is not applied to accidents, it would lead to the impossible consequence that a single accident of knowledge would simultaneously necessitate the attribute of being knowing in multiple individuals (al-Qāḍī ʿAbd al-Jabbār 1962b, vol. 6, pt. 2, p. 151; Çetin 2025, p. 149). Given that an originated will subsisting in no substrate must nevertheless be classified as an accident (Ibn al-Dāʿī 2024, p. 27; Ibn Mattawayh 2009, vol. 1, p. 3), explaining how God is willing (murīd) by means of a temporally originated will subsisting in no substrate constitutes a problem in its own right within the Bahshamī tradition. Moreover, assuming the existence of two eternal beings, the question of to which of them the will should be attributed gives rise to further difficulty.

According to this objection, if an originated will does not inhere in any substrate, there is no reason why it should necessitate God’s being willing rather than another being’s being willing, for there is no basis of particularization that would distinguish a will without a substrate as belonging to one particular essence rather than another (al-Nasafī 1990, vol. 1, p. 379; al-Rāzī 1986, vol. 1, pp. 216–17). In response to this objection, Bahshamī theologians offer the following argument: When a will inheres in us, or more precisely, when it inheres in our hearts, it necessitates our being willing. By contrast, when it does not inhere in us, its particularization to us ceases, and it can no longer necessitate our being willing. Accordingly, the Bahshamī theologians maintain that an originated will subsisting in no substrate necessitates only God’s being willing precisely because it is without a substrate (al-Buṭḥānī 2011, p. 204; Mānkdīm Shashdīw 1996, p. 352; Aktaş 2025, pp. 130–31). However, this response further reinforces the objection under the hypothetical assumption of two eternal beings. For if the assertion that only God can be willing by means of a will subsisting in no substrate is predicated exclusively on the will’s lack of a substrate, then no criterion would remain to explain why the same reasoning should apply to only one of the two hypothetical eternal beings. In this case, it would no longer be possible to maintain that the will subsisting in no substrate belongs exclusively to one of the two eternal beings; rather, both would have to be willing by means of the same will. Consequently, when one of the two eternal beings wills the motion of a body, the other must necessarily possess the same will, resulting in both eternal beings willing the same thing. It can thus be concluded that a state of conflict between the two eternal beings is not a conceivable phenomenon.

Muʿtazilī texts explicitly address the problem of how mutual hindrance can be conceived between two eternal beings within the framework of the doctrine of an originated will subsisting in no substrate and propose various solutions to resolve it. Some of these solutions were subsequently subjected to critical examination within the Bahshamī tradition. Al-Qāḍī ʿAbd al-Jabbār, who presents this critique, also sets forth his own response along with the explanations advanced by earlier theologians. Al-Qāḍī ʿAbd al-Jabbār’s primary response is to demonstrate that the objection raised against the doctrine of an originated will subsisting in no substrate does not invalidate the argument from mutual hindrance itself. Rather, it is a specific example employed in its formulation that is targeted. According to this, the problem arises in the example in which one of the two eternal beings wills the motion of a body, whilst the other wills its rest. Nonetheless, according to al-Qāḍī ʿAbd al-Jabbār, this problem is not associated with the logical structure of the argument from mutual hindrance in itself; rather, it is limited to that specific illustration. Since the purpose of the argument is to demonstrate the impossibility of the existence of two eternal beings through the possibility of conflict, the objection likewise loses its force once another example capable of serving this purpose is adopted. Indeed, Muʿtazilī theologians accept the principle that the coherence and validity of an inference is not undermined by the shifting of examples which establish the same judgment in the process of inference (Ḥafājī 2022, vol. 1, p. 161). For this reason, al-Qāḍī replaces the example in which one eternal being wills motion while the other wills rest with the example in which one eternal being wills a particular thing while the other has aversion (karāha) toward that same thing. This approach serves to eliminate the problem arising from the doctrine of an originated will subsisting in no substrate. Concomitantly, the conclusion derived from the argument from mutual hindrance remains unaltered. In this respect, al-Qāḍī ʿAbd al-Jabbār’s response aims to uphold the validity of the argument from mutual hindrance by demonstrating that the objection is directed not at the proof itself, but only at a specific example employed in its articulation (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, p. 284; al-Sarakhsī 2026, vol. 2, p. 191; al-Sharīf al-Murtaḍā 1381 HS, vol. 2, pp. 275–76; Ibn al-Malāḥimī 2012, p. 576). While this response is noteworthy insofar as it preserves the logical structure of the argument from mutual hindrance, it does not entirely eliminate the problem arising from the doctrine of an originated will subsisting in no substrate. This is because the main target of the critique is not a specific example, but rather the question of how an originated will subsisting in no substrate can be particularized to only one of two hypothetical eternal beings. Consequently, the substitution of the concepts of motion and rest with those of will and aversion does not resolve the problem. Indeed, al-Juwaynī likewise argues that the Muʿtazilī endeavor to elucidate the issue of mutual hindrance by positing that one of the two eternal beings wills a particular thing while the other merely feels aversion toward it fails to resolve the problem. According to al-Juwaynī, once the source of aversion toward a particular thing is examined, it ultimately proves to rest upon will. Consequently, just as it is not possible to conceive of any disagreement between two eternal beings with respect to will, it is similarly not possible to conceive of any disagreement between them with respect to intention or orientation (qaṣd), both of which depend upon it. In that case, it is contradictory to assert that no disagreement can be conceived with respect to will while simultaneously endeavoring such disagreement in terms of aversion. Furthermore, the explanation that a conflict between two eternal beings can be conceptualized on the basis that one creates the will directed towards a particular act while the other creates aversion towards that same act (al-Sharīf al-Murtaḍā 1381 HS, vol. 2, pp. 275–76) is likewise unacceptable from the Muʿtazilī perspective. The Muʿtazilīs argue that the objection according to which, if God is willing by means of an originated will, then that will, like all other originated entities, must itself be willed by another will, thereby leading to an infinite regress of originated wills (al-Shahrastānī 1934, pp. 244–45), is valid only if one assumes that a will must necessarily be the object of another will. Indeed, in order to circumvent an infinite regress of originated wills subsisting in no substrate, the Muʿtazila of Baghdad maintained that neither will nor aversion could itself be the object of another will (al-Nīsābūrī 1979, p. 363). The Basran Muʿtazilīs, by contrast, accepted that a will may be the object of another will, but denied that this is necessary. Accordingly, they maintained that not every will must depend upon another will (al-Qāḍī ʿAbd al-Jabbār 1962b, vol. 6, pt. 2, p. 190; Mānkdīm Shashdīw 1996, pp. 453–54; Ibn Mattawayh 2009, vol. 2, pp. 529–30). However, from either perspective, it is evident that neither will nor aversion can serve as the object of another will in the manner required here. Consequently, the assertion that one of the two eternal beings creates a will directed towards a particular act, while the other creates aversion towards that same act, is incompatible with the Muʿtazilī doctrine of will and therefore cannot provide a basis for the assumption of two eternal beings or for the possibility of conflict between them (al-Juwaynī 1969, p. 369).

As a second solution to the problem of how conflict between two eternal beings can be conceptualized within the framework of the doctrine of an originated will subsisting in no substrate, al-Qāḍī ʿAbd al-Jabbār reports the view of Abū Isḥāq Ibrāhīm b. ʿAyyāsh (d. 386/996). Ibn ʿAyyāsh’s solution elucidates the impact of will on an act by reference to the agent who originates it. According to this view, a will directs only the action of the agent who creates it, whereas a will created by another agent has no determining effect upon that agent’s action. For example, even if God creates in the heart of a hungry person a will to refrain from eating, the person will nevertheless will to eat because he knows the benefit of eating and the harm of remaining hungry. Similarly, if a will to enter Hell and an aversion to entering Paradise are created in a person standing between Paradise and Hell, that person will nevertheless choose to enter Paradise. These examples demonstrate that the will that determines an act is not one created by another, but rather, it is one created by the very agent who performs the act. When this explanation is applied to the problem of mutual hindrance in the context of the doctrine of an originated will subsisting in no substrate, the will that determines God’s bringing about the motion of the body is the will He Himself creates. Conversely, the will that determines the second eternal being’s bringing about the body’s remaining at rest is the will that it likewise creates itself. Accordingly, the fact that both wills can be attributed to both eternal beings given that they do not inhere in any substrate does not imply that they exercise the same determining influence over the act.

For the efficacy of a will is contingent not on its relation to a substrate or on particularization, but rather on the agent who creates it. Therefore, Ibn ʿAyyāsh attempts to overcome the objection that a will subsisting in no substrate lacks particularization by establishing the efficacy of the will with respect to an act in the will created by the very agent who performs it. On this basis, he argues that the mutual hindrance between two eternal beings is, at least in theory, conceivable (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, p. 285; Ibn al-Malāḥimī 2012, p. 576; al-Buṭḥānī 2011, pp. 120–21). Al-Qāḍī ʿAbd al-Jabbār reports this explanation without providing an evaluation of it. Nevertheless, it would not be accurate to argue that Ibn ʿAyyāsh’s approach entails the conclusion, rejected by the Muʿtazila, that a will must itself be the object of another will. For the issue here is not that an existing will becomes the object of another will, but rather that an agent directly creates a will of its own. Accordingly, Ibn ʿAyyāsh does not identify the origination of a will with its being the object of another will. Instead, he posits that the determining efficacy of will with respect to an act lies in its belonging to the very agent who creates it. For this reason, his approach offers an alternative solution to the problem of mutual hindrance in the context of an originated will subsisting in no substrate, while also allowing for the theoretical conceivability of conflict between two eternal beings.

In the wake of the preceding elucidations, al-Qāḍī ʿAbd al-Jabbār proffers his own resolution to the conundrum of how conflict between two eternal beings can be conceptualized within the ambit of the doctrine of an originated will subsisting in no substrate. The solution under discussion is predicated on the Bahshamī principle that a single object of power (maqdūr) cannot proceed from two powerful agents (qādirān) (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, pp. 255–66; n.d.-b, vol. 8, pp. 131–61). Consequently, although a will subsisting in no substrate may be attributed to both eternal beings, this does not necessitate that they be directed towards the same object of power, for the will of each eternal being relates (taʿalluq) exclusively to its own object of power. Within this framework, while each of the two eternal beings is capable of willing its own act, the act that is the object of power of the other becomes impossible for it. Consequently, the fact that the will does not inhere in any substrate does not necessitate that both wills pertain to a single object of power. Conversely, the basis for conflict is perpetuated by each eternal being’s will relating exclusively to its own object of power. Al-Qāḍī ʿAbd al-Jabbār’s explanation thus provides a response to the objection concerning mutual hindrance in the context of an originated will subsisting in no substrate. This is achieved by grounding it not in the attribution of the will, but in the attribution of the object of power. It is on this basis that the explanation is provided for how conflict between the two eternal beings remains conceivable (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, p. 286).

Although other responses can be found in Muʿtazilī texts concerning how conflict between two eternal beings could be conceived within the framework of the doctrine of an originated will subsisting in no substrate, these responses were regarded as weak by later Bahshamī theologians. For instance, according to one such response, since it is held to be rationally possible for the wills of two living beings to differ, the existence of a second eternal being besides God would contradict this principle. Consequently, it must be rejected (Mānkdīm Shashdīw 1996, p. 272). However, later Bahshamī theologians deemed this explanation inadequate, as the possibility of differing wills is a principle specific to the observable world (shāhid), in which each living being possesses a will inhering in its own substrate. Once the doctrine of an originated will subsisting in no substrate is adopted, the hypothetical eternal beings cannot be said to possess such a will; consequently, no difference in will between them can be conceived (al-Muḥallī n.d., fols. 91a–b).

Moreover, this explanation does not directly address the objection raised against the doctrine of an originated will subsisting in no substrate. Instead, it serves as an independent proof of God’s oneness apart from the argument from mutual hindrance (al-Buṭḥānī 2011, p. 122).

3.2. Motive and Mutual Hindrance

The Muʿtazilī endeavour to overcome the problem arising from the doctrine of an originated will subsisting in no substrate by establishing the possibility of conflict between two eternal beings in the differentiation of motive (dāʿī) and deterrent (ṣārif) gives rise to a second problem for the argument from mutual hindrance. The crux of the issue is how the motive and deterrent of one eternal being could differ from those of another, given that both are assumed to be knowing and wise by essence. For if motive and deterrent are held to depend upon the agent’s knowledge, it becomes necessary to explain how one of the two eternal beings can possess a motive to bring about a particular act, while the other possesses a deterrent directed towards preventing that very act. At the same time, insofar as motive and deterrent determine which acts God performs or refrains from performing, their role also raises the question of how such determination can be reconciled with the infinitude and unrestrictedness of the divine will.

This issue is addressed in Muʿtazilī texts in terms of how the motives of two eternal beings, each knowing and wise by essence, could differ with respect to their actions (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, p. 262; al-Buṭḥānī 2011, p. 120; Mānkdīm Shashdīw 1996, p. 283; Ibn al-Malāḥimī 2012, p. 567). However, within Sunnī theological texts, it is also discussed in relation to the doctrine of an originated will subsisting in no substrate.

In Muʿtazilī theology, motive and deterrent are explained as depending upon the agent’s knowledge. According to this view, when an agent knows that an act is either good or evil, this knowledge gives rise either to the motive that inclines the agent to perform the act or to the deterrent that leads the agent to refrain from it. Thus, when a wise being knows that an act is evil and has no need of it, that knowledge gives rise to the deterrent that leads the agent to refrain from the act (al-Qāḍī ʿAbd al-Jabbār 1962a, vol. 6, pt. 1, p. 196; al-Juwaynī 1969, p. 369; al-Raṣṣāṣ 2011, p. 5; Demir 2026, pp. 15–23; Demir Bektaş 2022, pp. 88–102).

Al-Juwaynī develops his critique based on this conceptual framework in two stages. Firstly, drawing upon the Muʿtazilī principle that a will cannot be the object of another will, al-Juwaynī raises, as an objection, the possibility that a will may come into existence independently of motive. In other words, if it is impossible for a will to come into existence based on another will, why should it necessarily be assumed to come into existence based on a motive? His second and more fundamental criticism is predicated on the question of how motives and deterrents could differ, with the doctrine of an originated will subsisting in no substrate constituting the point of departure. According to him, if two eternal beings are both willing by means of the same will, because that will does not inhere in any substrate, then it cannot be explained how one possesses a motive with respect to a particular act while the other possesses a deterrent with respect to that same act. Consequently, two eternal beings willing by means of the same will must either both possess a motive with respect to the same act or both possess a deterrent with respect to it. Al-Juwaynī then advances his critique further by positing an even stronger possibility. For a number of acts, the act itself and its opposite may be entirely equal with respect to benefit (maṣlaḥa), grace (luṭf), and the possibility of occurrence. In such a case, there would be neither a motive leading one to perform the act nor a deterrent leading one to refrain from it. In such circumstances, it becomes unfeasible to elucidate how the two eternal beings could be directed towards different actions based on differences in their motives (al-Juwaynī 1969, pp. 369–70). For mutual hindrance requires that the two eternal beings possess different motives regarding performing and refraining from the same act. In contradistinction, if the motive and the deterrent are contingent upon the agent’s knowledge, such a difference in motives cannot be conceived between two beings who are knowing by essence.

It should be noted that the Bahshamī and Ḥusaynī traditions –the latter referring to the followers of Abū l-Ḥusayn al-Baṣrī (d. 436/1044)– adopted different positions regarding the relationship between the argument from mutual hindrance and motive. Bahshamī theologians maintained that motives can differ both with respect to the act itself and with respect to the agent. In this context, al-Qāḍī ʿAbd al-Jabbār states that acts are not confined to those that are morally good or evil, but that there are also permissible (mubāḥ) acts. Thus, one of two eternal beings could possess a motive to perform a permissible act, while the other could choose to abstain from it, and in such a case conflict between the two could be conceived (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, p. 262). Furthermore, the Bahshamī theologians maintain that a motive is not a sufficient condition for the occurrence of an act (al-Muḥallī n.d., fol. 91b; Ibn al-Malāḥimī 2012, p. 563). Consequently, even if an agent possesses a motive with respect to a particular act, it may nevertheless choose not to perform it. By denying that motive necessarily determines action, this position also avoids making divine action strictly determined by motive and thereby preserves the unrestricted character of the divine will. Therefore, one of the two eternal beings may choose to leave a body at rest despite knowing that moving it is good, while the other may choose to set that same body in motion (al-Sharīf al-Murtaḍā 1381 HS, vol. 2, p. 274). However, to maintain that an act can occur either contrary to a motive or in the absence of any motive amounts to reducing the possibility of conflict between two eternal beings solely to a difference in will. This, in turn, raises the objection previously discussed, namely, how two eternal beings can will opposite acts within the framework of the doctrine of an originated will subsisting in no substrate (al-Juwaynī 1969, pp. 370–71). According to an alternative interpretation proposed by al-Qāḍī ʿAbd al-Jabbār and subsequently adopted by later Bahshamī theologians, the occurrence of conflict is not contingent upon the actual difference in motives between two eternal beings, but on the possibility of such a difference. For to accept that their motives actually differ would be to presuppose the existence of a second eternal being besides God, whereas the very aim of the argument from mutual hindrance is to demonstrate the impossibility of such a hypothesis. It is therefore posited that the possibility of a divergence in motives between two eternal beings is adequate for the formulation of the argument from mutual hindrance (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, p. 281; Mānkdīm Shashdīw 1996, pp. 282–83; al-Buṭḥānī 2011, p. 120).

While Bahshamī theologians regard the conflict of motives between two eternal beings as a mere possibility, Abū l-Ḥusayn al-Baṣrī and Ibn al-Malāḥimī (d. 536/1141), who maintain that an act can occur only based on a motive, consider such a conflict of motives between two eternal beings to be impossible (Ibn al-Malāḥimī 2012, p. 563; al-Muḥallī n.d., fol. 91b; Schmidtke 2016, pp. 170–71; Tektaş Erdoğan 2025, pp. 302–5). From their perspective, the principle advanced by the Bahshamīs, namely that “the motives of two living beings can differ,” is valid only in the observed world. The reason for this is that, in the observed world, two beings may differ in their knowledge of the moral status of actions. Nevertheless, in the case of two beings who are omniscient by virtue of their essences, this principle cannot be said to apply (Ibn al-Malāḥimī 2012, pp. 567–68). This approach precludes the possibility of conflict, on which the argument from mutual hindrance is based. Consequently, it gives rise to the further question of how Ibn al-Malāḥimī grounds the oneness of God. Indeed, the Zaydī representative of the Ḥusaynī school, Yaḥyā b. Ḥamza (d. 749/1348), notes that Ibn al-Malāḥimī establishes the oneness of God by means of a proof based on the principle that “anything for which there is no evidence and which is not known must be regarded as nonexistent.” (al-Muʾayyad bi-llāh 2008, vol. 1, p. 342; 2024, vol. 3, p. 24).

The objections previously discussed regarding how the motives of two eternal beings who are omniscient by virtue of their essences could differ led to the proposal that the concept of a “capable being” (qādir) is sufficient for the argument from mutual hindrance (Ibn Mattawayh 1965, vol. 1, p. 217). However, this proposal raises another objection: how two eternal beings, each assumed to be capable by virtue of their essences, could be related to different objects of power, and thus on what basis a conflict between them could be explained.

3.3. Eternal Being Capable by Virtue of Its Essence and Mutual Hindrance

Another objection to the possibility of constructing the argument from mutual hindrance on Muʿtazilī principles rests on the conception of a being that is capable by virtue of its essence (qādir li-dhātihī). The objection under discussion is structured around two main claims: (i) that two eternal beings who are capable by virtue of their essences must have the same objects of power (maqdūrāt), and (ii) that neither of two eternal beings who are capable by virtue of their essences can have any priority over the other with respect to bringing an object of power (maqdūr) into existence. According to this objection, if a second eternal being besides God is posited, then, by virtue of its eternality, it would have to be equal and similar to God in all essential attributes. Since, according to the Muʿtazilīs, God is capable by virtue of His essence, the hypothetical second eternal being would likewise have to be capable by virtue of its essence. If divine infinity entails that such power is unlimited, however, the assumption of two eternal beings capable by virtue of their essences raises the question of whether the power of each could remain unlimited without being restricted by that of the other. For the acceptance of both as capable by virtue of their essence entails that their capabilities pertain to the same things.

Indeed, this objection is rendered more perspicuous when contemplated in conjunction with both al-Qāḍī ʿAbd al-Jabbār’s discussion in the context of his refutation of the Dualists (Şeker 2026, pp. 255–56) and his explanation of the principles underlying the first proof that he presents before the argument from mutual hindrance (tamānuʿ) to establish the oneness of God. In presenting this initial proof, al-Qāḍī ʿAbd al-Jabbār commences by establishing: (i) that an eternal being is eternal by virtue of its essence and that eternality (qidam) is God’s most distinctive attribute; (ii) that sharing the attribute of eternity necessarily entails sharing all other essential attributes; and (iii) that a single object of power (maqdūr) cannot belong to two capable beings (qādirān) (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, pp. 250–66). Having established these principles, al-Qāḍī proceeds to argue that if the existence of a second eternal being besides God is assumed, that being must likewise be capable by virtue of its essence. Consequently, if one of two beings that are eternal by virtue of their essences is related to any object of power (maqdūr), the other must necessarily be related to the same object of power. Otherwise, two beings who share the most distinctive attribute, eternality, would be similar in this respect but different in what they pertain to, which would contradict the second principle. Yet, since al-Qāḍī deems it impossible for a single object of power to pertain to two agents, he rejects the possibility that the same object of power could belong to two agents and concludes that there cannot be a second eternal being who is capable by virtue of its essence besides God (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, pp. 267–68). Thus, in this proof, God’s oneness is established on the basis of the contradiction between the necessity that two eternal beings who are capable by essence share the same object of power and the principle that a single object of power cannot belong to two agents.

The principles articulated by al-Qāḍī ʿAbd al-Jabbār in the context of his first proof, in conjunction with the elucidations provided above, manifest a substantial contradiction with the assumptions underlying the argument from mutual hindrance, which he presents as his second proof. In the first proof, he argues that the objects of power of two beings who are capable by their very essence must necessarily be identical, whereas the argument from mutual hindrance rests on the premise that two such beings are related to different objects of power, and that this difference gives rise to conflict. This contradiction is made explicit in the following objection, which al-Qāḍī ʿAbd al-Jabbār himself records while explaining the argument from mutual hindrance:

If it is said: Your reliance on this proof [the argument from mutual hindrance] invalidates the position you adopted based on the first proof. For this proof requires that, for mutual hindrance to occur between two capable beings, the object of power of one must differ from that of the other, since if the object of power is one and the same, mutual hindrance becomes impossible. By contrast, the first proof requires that both share the same object of power; indeed, according to that proof, it is impossible for their objects of power to differ. Therefore, reliance on one of these proofs undermines reliance on the other. If the first proof is sound, the second must be invalid; and if the second is sound, the first must be invalid. The reason is that the first proof assumes that the two eternal beings share the same object of power, whereas the second assumes that their objects of power are different. These two assumptions are mutually contradictory (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, p. 295).

This objection, regarded as a challenging question for the Muʿtazilī theologians (Ibn al-Murtaḍā n.d., fol. 113b), clearly prompted the development of various solutions that were subsequently reexamined and refined. The initial response transmitted to this objection is attributed to Ibn ʿAyyāsh. Ibn ʿAyyāsh advanced the argument that, in accordance with the principle that a single object of power cannot belong to two capable beings, the objects of power of any two agents, whether capable by their very essences or by virtue of a power (qādir bi-qudra), must necessarily be different. Accordingly, he maintained that even if two beings are capable by virtue of their essences, it is impossible for them to be related to the same object of power. However, Mānkdīm Shashdīw has criticized this explanation on the grounds that it requires two beings who share the attribute of eternality (qidam) to be different in some respect (Mānkdīm Shashdīw 1996, pp. 280–81). Subsequently, later Muʿtazilī theologians also deemed Shashdīw’s response to be unsatisfactory. They contended that it was, in itself, incompatible with the principle that a single object of power cannot belong to two capable beings (al-Muḥallī n.d., fol. 91a; Ibn al-Murtaḍā n.d., fol. 113b).

Al-Qāḍī ʿAbd al-Jabbār offers two distinct explanations for this problem: one in al-Mughnī, and the other transmitted by Ibn al-Malāḥimī from Taʿlīq al-Muḥīṭ (Notes on al-Muḥīṭ). According to the explanation provided by Ibn al-Malāḥimī, al-Qāḍī ʿAbd al-Jabbār maintains that conflict between two capable beings is possible in principle. However, once it is taken into account that these two beings are capable by virtue of their essences, such a conflict, though possible in principle, becomes impossible. On this basis, he argues that the objection itself confirms the oneness of God and, taking the objection as his point of departure, reformulates the proof differently. Although conflict between two capable beings is possible in principle, the existence of two beings who are capable by virtue of their essences renders such conflict impossible. Therefore, the existence of a second eternal being, which would invalidate a situation that is rationally and conceptually possible, cannot itself be admitted; consequently, the existence of a second eternal being besides God must be negated (Ibn al-Malāḥimī 2012, pp. 559–61; al-Sharīf al-Murtaḍā 1381 HS, vol. 2, p. 278). Nevertheless, it is evident that al-Qāḍī’s elucidation does not comprehensively address the aforementioned objection. Indeed, it paves the way for a new criticism, namely, that the argument from mutual hindrance is abandoned in favor of a different proof (Mānkdīm Shashdīw 1996, pp. 281–82). The crux of the objection is not the demonstration of God’s oneness. Rather, it concerns how conflict between two beings capable by virtue of their essences can be conceived and how the argument from mutual hindrance can be reconciled with its own premises. Instead of resolving this problem, al-Qāḍī takes the objection as his starting point. Subsequently, he advances an alternative form of proof to demonstrate the impossibility of a second eternal being. Consequently, while this explanation may be regarded as an independent argument for establishing God’s oneness, it does not appear sufficiently persuasive as a response to the objection under consideration.

Al-Qāḍī ʿAbd al-Jabbār responds in al-Mughnī to the aforementioned objection, which is based on the claim that the two proofs contradict one another, by appealing to the epistemological function of proofs. In this context, he argues that each of the two proofs should be evaluated independently according to its own premises and that, for this reason, each remains a valid and independent proof of the oneness of God. According to him, the crux of the argument pertains to the fundamental question of whether both proofs must be known in unison to substantiate the oneness of God, or whether each proof possesses independent probative value.

In this regard, al-Qāḍī ʿAbd al-Jabbār first maintains that these two approaches, which proceed from the sameness or difference in the objects of power, are in fact two independent proofs that aim to reach the same conclusion through different premises. Consequently, the second proof is predicated on the assumption that, if two capable beings exist, mutual hindrance would occur between them. Here, the starting point is not whether these beings are capable by virtue of their essences or by means of a power, but rather the general notion of two capable beings. In contrast, the first proof is founded on the premise that, if there are two beings who are both capable by virtue of their essences, their objects of power must necessarily be identical. Consequently, the oneness of God can be substantiated through either proof. For instance, someone who is unaware of the principle that the objects of power of two beings capable by virtue of their essences must be identical could nevertheless affirm the impossibility of a single object of power belonging to two capable beings, accept the possibility of conflict between two capable beings, and thereby use the second proof to demonstrate God’s oneness. In this case, ignorance of the first proof does not undermine the validity of the inference. Conversely, an individual who, based on the first proof, concludes that the objects of power of two beings capable by virtue of their essences must be identical may demonstrate the impossibility of a second eternal being, and hence God’s oneness, without relying on the premises of the argument from mutual hindrance. Consequently, as long as each proof can yield the same conclusion independently, both retain their epistemological status as independent proofs. For this reason, according to al-Qāḍī ʿAbd al-Jabbār, the issue at hand is not the progression of a single, complementary proof into multiple stages, but rather the existence of two distinct proofs that, while pursuing the same objective, are founded upon different initial principles (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, pp. 295–96; cf. al-Sharīf al-Murtaḍā 1381 HS, vol. 2, pp. 277–78; Ibn al-Malāḥimī 2012, pp. 575–76; Mānkdīm Shashdīw 1996, p. 281; Ibn al-Murtaḍā n.d., fol. 113b).

Furthermore, al-Qāḍī ʿAbd al-Jabbār notes that the possibilities contemplated in each proof are not themselves the subject of the argument, but rather hypothetical assumptions employed in constructing the inference. According to him, the assumption underlying the argument from mutual hindrance, namely that if there were a second capable being besides God, mutual hindrance would occur between them, is not intended to describe an actually possible situation, but rather to demonstrate the impossibility of a second eternal being. Consequently, the fact that this assumption does not correspond to reality does not invalidate the proof. The objective is not to assert the existence of a second eternal being, but rather to present a consideration that demonstrates the impossibility of such an assumption. For this reason, differences in the hypothetical assumptions do not signify any actual contradiction between the two proofs (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, pp. 297–98).

Al-Qāḍī ʿAbd al-Jabbār refutes the second assertion that neither of the two eternal beings capable by virtue of their essences can have any priority over the other with respect to bringing an object of power into existence. According to him, if the acts willed by two beings capable by virtue of their essences do not occur together, this indicates that each impedes the other and that both are therefore rendered incapable. However, incapacity cannot be conceived with respect to a being that is capable by virtue of its essence. For this reason, al-Qāḍī ʿAbd al-Jabbār regards the possibility that neither of the acts willed by the two beings comes into existence as a consequence incompatible with the very notion of an eternal being (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, p. 294; Ibn al-Malāḥimī 2012, pp. 572–73; al-Sharīf al-Murtaḍā 1381 HS, vol. 2, p. 277).

In responding to the objection that neither of two eternal beings capable by virtue of their essences can have any priority over the other with respect to bringing an object of power into existence, al-Qāḍī ʿAbd al-Jabbār also refers to Abū Hāshim’s understanding of the argument from mutual hindrance. This discussion is of significance as it reflects Abū Hāshim’s approach to the argument. According to Abū Hāshim, genuine mutual hindrance cannot occur between two beings capable by virtue of their essences. If conflict is conceived only with respect to a particular object of power, no genuine mutual hindrance can be said to occur, since each capable being would still have many other objects of power that it could bring into existence. For mutual hindrance means that an agent is completely prevented from carrying out the act it wills.

On the other hand, if the conflict is assumed to encompass all objects of power, it becomes impossible for either capable being to bring any act into existence. Since it is meaningless to speak of the obstruction of something that is already impossible, this possibility must also be rejected. Accordingly, genuine mutual hindrance cannot be conceived between two beings capable by virtue of their essences. For if such a conflict is assumed to occur, and neither of the two capable beings has priority over the other with respect to bringing an object of power into existence, neither of the acts willed by them can come into existence. This, however, demonstrates that both capable beings are weak and that their objects of power are limited. The weakness of both capable beings and the limitation of their objects of power are incompatible with the conception of an eternal being established by proof (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, pp. 294–95). This result is likewise incompatible with divine infinity, which requires divine power to remain unlimited and unrestricted by any other agent. Indeed, a line of reasoning closely paralleling Abū Hāshim’s argument is reiterated in the later Zaydī-Muʿtazilī tradition by Yaḥyā b. al-Ḥasan al-Saʿdī al-Qurashī (d. 780/1378–79) (al-Saʿdī al-Qurashī 2014, vol. 2, pp. 366–69). As can be understood from the account of Abū Hāshim’s view transmitted by al-Qāḍī ʿAbd al-Jabbār, Abū Hāshim does not ground the argument from mutual hindrance (tamānuʿ) on the assumption of actual conflict between two beings capable by virtue of their essences. Instead, he establishes it on the necessary principles regarding the nature of a being that is both capable by virtue of its essence and eternal. His objective, therefore, is not to determine which act would occur in the event of a conflict between two capable beings, but to demonstrate that genuine tamānuʿ cannot be conceptualized with respect to two beings capable by virtue of their essences. The assumption of such a conflict would entail the weakness of both agents and the limitation objects of power, which is incompatible with the concept of an eternal being established by proof.

3.4. The Indicative Function of Possibility (Imkān) and Mutual Hindrance

In both Sunnī and Muʿtazilī texts, the concept of possibility is regarded as having a distinct evidential function as one of the central principles of the argument from mutual hindrance (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, pp. 281–82; Mānkdīm Shashdīw 1996, p. 283; al-Juwaynī 1969, p. 361). It is maintained that not only the occurrence of a situation in reality, but even its mere possibility, can indicate certain consequences. In this context, the actual occurrence of one of two capable beings preventing the other clearly demonstrates the hindered being’s incapacity and weakness. Likewise, the mere possibility of such prevention is held to indicate the incapacity and weakness of the hindered party. Indeed, in the argument from mutual hindrance, the hypothesis of two eternal beings, the possibility of disagreement between them, and the prevention of one by the other are all considered merely as possibilities. This is because accepting the actual occurrence of such disagreement or prevention would, in effect, amount to accepting the real existence of a second eternal being, which the argument is intended to refute. Therefore, the logical force of the argument rests not on actuality, but on the evidential significance of possibility.

It is precisely at this point that a new problem arises concerning the Muʿtazilī understanding of the evidential significance of possibility in the argument from mutual hindrance and its application of the same principle in other contexts. With certain exceptions, such as Ibrāhīm b. Sayyār al-Naẓẓām (d. 231/845), Muʿtazilī theologians maintain that God is capable of committing evil acts and therefore that the occurrence of such acts may be conceived as possible with respect to God. Concurrently, however, they regard the actual occurrence of such acts from God as impossible. According to them, an evil act can only proceed from ignorance (jahāla), need (ḥāja), or deficiency (naqṣ). Since ignorance and need cannot be conceived with respect to God, the actual occurrence of an evil act from God is likewise impossible. Thus, while the Muʿtazilīs accept the possibility of evil acts with respect to God, they maintain that this possibility does not indicate that God is ignorant or in need, but that only the actual occurrence of such acts would have such evidential significance. The core problem arises precisely at this point of distinction. This distinction exposes the Muʿtazilīs to the charge of inconsistency regarding the evidential significance of possibility. Indeed, while they maintain that the mere possibility of God’s committing an evil act does not indicate any divine deficiency, they also hold that the mere possibility of conflict and mutual hindrance between two eternal beings, even if never actualized, indicates the incapacity of the hindered party. Nevertheless, in both cases, the issue pertains exclusively to hypothetical possibility, as opposed to actuality. Consequently, while the Muʿtazilīs reject the evidential significance of possibility in one case, they attribute evidential significance to the same possibility in another. This selective application of the evidential significance of possibility gives rise to a methodological inconsistency in the context of the argument from mutual hindrance. As a result, this objection confronts the Muʿtazilīs with three unacceptable alternatives. Either, as al-Naẓẓām maintained, God is not capable of committing evil acts (al-Ashʿarī 1980, Maqālāt al-Islāmiyyīn, p. 555); or the evidential significance of possibility must be acknowledged both with respect to God’s capability of committing evil acts and in the argument from mutual hindrance; or, finally, possibility must be regarded as having no evidential significance in either case (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, p. 288; al-Juwaynī 1969, pp. 372–76; Ibn al-Malāḥimī 2012, p. 570; al-Sharīf al-Murtaḍā 1381 HS, vol. 2, p. 276; Ibn al-Murtaḍā n.d., fol. 113a).

To resolve this problem, Muʿtazilī theologians argued that the evidential significance of possibility in these two cases cannot be treated as belonging to the same category. For it is definitively established that God is capable of acts which, if performed, would be evil or unjust (ẓulm), since a being capable by virtue of its essence must be capable of everything that is possible (al-Qāḍī ʿAbd al-Jabbār 1962a, vol. 6, pt. 1, p. 129; Ibn Mattawayh 1965, vol. 1, p. 248; Mānkdīm Shashdīw 1996, p. 317; Demir Bektaş 2022, pp. 63–77). It is likewise established by definitive proof that God is neither ignorant nor in need. Therefore, to infer from God’s capability of committing unjust acts that He is ignorant or in need would amount to contradicting these definitive proofs. By contrast, the situation arising from the assumption that there are two eternal beings and that one prevents the other is of a different nature. For the very phenomenon of prevention inherently signifies the incapacity, weakness, and insufficiency of the one who is prevented when confronted with superior power. Such a limitation of divine power would be incompatible with divine infinity, since an infinite power cannot be restricted or rendered ineffective by another power. Consequently, the conclusion reached in the second case does not contradict a truth already established by definitive proof, as it would in the first. Thus, while God’s capability of committing evil acts does not imply that He is ignorant or in need, the possibility of conflict between two eternal beings capable by virtue of their essences, and of one preventing the other, does indicate the weakness and incapacity of the one who is prevented (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, p. 291; al-Sharīf al-Murtaḍā 1381 HS, vol. 2, p. 276; Ibn al-Malāḥimī 2012, p. 571; Ibn Mattawayh 1965, vol. 1, pp. 218–19; Ibn al-Murtaḍā n.d., fol. 113a).

Al-Qāḍī ʿAbd al-Jabbār maintains that there is a fundamental distinction between God’s capability of committing evil acts, which does not imply ignorance or need, and the possibility of being prevented, which implies the superior power of the one who prevents. According to him, acts that indicate something about the agent’s state (ḥāl) fall into two categories. The first category consists of acts whose possibility of proceeding from a particular agent indicates that the agent possesses a certain state. In this case, the relevant state is the agent’s capability, which makes the act possible. Therefore, the possibility of an act and its actual occurrence have the same evidential significance. Just as the possibility of an act proceeding from a particular agent indicates that the agent is capable, so too does the actual occurrence of the act. By contrast, the second category consists of acts that indicate the agent’s inclination to perform or refrain from an act on account of a particular state. In this case, the possibility of the act and its actual occurrence do not have the same evidential significance, since what is decisive is not the agent’s capability but rather qualities such as ignorance, need, and similar conditions that lead the agent to choose the act. Al-Qāḍī ʿAbd al-Jabbār justifies this distinction by reversing his opponent’s argument. If the possibility of an act proceeding from a particular agent does not indicate that the agent is capable, then the actual occurrence of the same act cannot indicate the agent’s capability either. For the actual occurrence of the act indicates the agent’s capability only because it presupposes the possibility of the act proceeding from that agent. Therefore, if the evidential significance of possibility is rejected in this case, the evidential significance of the actual occurrence of the act must likewise be rejected. Accordingly, al-Qāḍī ʿAbd al-Jabbār argues that if the possibility of an act indicates the agent’s capability, then its actual occurrence must do so as well; otherwise, neither inference remains valid. According to him, however, the same reasoning does not apply to evil or unjust acts. A person’s capability of committing injustice does not indicate that the person is ignorant or in need, whereas the actual commission of injustice does indicate such deficiencies. Consequently, in this category the possibility of an act and its actual occurrence do not possess the same evidential significance. The possibility of the act indicates only the agent’s capability, whereas its actual occurrence also reveals the qualities that lead the agent to choose the act. The conclusion al-Qāḍī ʿAbd al-Jabbār seeks to establish through this distinction is that God’s capability of committing evil acts does not imply that He is ignorant or in need, because in this case the possibility and the actual occurrence of the act do not have the same evidential significance. By contrast, since the possibility of prevention belongs to the category of acts that indicate the agent’s capability, there is no difference in evidential significance between the possibility and the actual occurrence of prevention. Indeed, if the possibility of prevention is accepted without acknowledging that the one who prevents is stronger, then the actual occurrence of prevention can no longer be said to indicate superior power either (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, p. 289; Ibn al-Malāḥimī 2012, p. 570).

Al-Qāḍī ʿAbd al-Jabbār concludes his discussion of this objection by clarifying when it is valid to link one proposition to another by means of a conditional. He explains that conditional statements can serve different functions: they may be used for informative purposes (ikhbār), rational evaluation (iʿtibār), or to emphasize remoteness or impossibility (tabʿīd). In informatively used conditionals, it is essential that a possible event not be made conditional on something known to be impossible. Conversely, making an impossible event conditional upon a possible one is valid, since the aim is not to establish a genuine conditional relationship, but to indirectly convey that the antecedent did not occur on the basis of the impossibility of the consequent. Thus, a statement like “If Zayd had entered the house, blackness would have turned whiteness” is invalid, as it makes a possible event conditional upon an impossible consequence. On the other hand, “If blackness had turned whiteness, Zayd would have entered the house” is valid, not because the turning of blackness into whiteness is regarded as possible, but because it indirectly conveys that Zayd did not enter the house by referring to the impossibility of the antecedent. Within this framework, al-Qāḍī ʿAbd al-Jabbār argues that the inference that God’s capability of committing evil acts entails His ignorance or need is invalid for the same reason: it makes the impossible (God’s being ignorant or in need) conditional upon the possible (God’s capability of committing evil acts). Such usage is not valid in informative conditionals, since the fundamental intent is to report what is already definitively known: namely, that God is, by His very essence, all-knowing and free from need. Since God’s being ignorant or in need is logically impossible regardless of whether or not God actually commits an evil act, making this impossible state conditional upon God’s capability of committing evil acts is not valid in informative conditional statements.

By contrast, al-Qāḍī ʿAbd al-Jabbār notes that the use of conditionals for rational evaluation (iʿtibār) is governed by different rules from those used for conveying information. In this context, an assumption is refuted by deriving an impossible consequence from it, since the aim is not to report actual events but to derive the consequences of a hypothetical assumption and thereby demonstrate its invalidity. Thus, a statement like “If God had committed an evil act, He would have had to be ignorant or in need,” while not valid as an informative statement, is sound as a rational evaluation: it is not intended to assert that God actually commits such acts, but to show that this assumption would necessarily entail an impossible consequence. Al-Qāḍī ʿAbd al-Jabbār maintains that the same principle applies to the argument from mutual hindrance. Accordingly, the statement, “If there were a second eternal being alongside God and, in the event of conflict, the will of one were realized, that one would have to be more powerful than the other,” is formulated not to report an actual event but to conduct a rational evaluation. In reality, the statement means that “if one could prevent the other, it would have to be more powerful,” and since it is logically impossible for one of two eternal beings to be more powerful than the other, the assumption of a second eternal being is thereby invalidated. Thus, in al-Qāḍī ʿAbd al-Jabbār’s view, the conditional in the argument from mutual hindrance is constructed for rational evaluation rather than for conveying information and therefore cannot be placed in the same category as informative conditionals in which ignorance or need is inferred from the assumption that God commits an evil act (al-Qāḍī ʿAbd al-Jabbār n.d.-a, vol. 4, pp. 292–94; al-Muḥallī n.d., fol. 92a). In conclusion, al-Qāḍī ʿAbd al-Jabbār neither absolutely accepts nor rejects the evidential significance of possibility; rather, he argues that its evidential significance varies according to the intended function of the conditional statement.

4. Conclusions

The argument from mutual hindrance, constructed upon different principles and assumptions by various kalām schools, has served as one of the principal proofs commonly employed to establish the oneness of God. The fact that each school formulates the argument on distinct premises according to its own theological system, however, has led to certain problems regarding how the argument from mutual hindrance can be grounded, particularly from the Muʿtazilī perspective. Notably, al-Qāḍī ʿAbd al-Jabbār’s own explanations of these problems, as well as his transmission of the views and proposed solutions of earlier theologians such as Abū Hāshim and Ibn ʿAyyāsh, demonstrate that the debate extends back to an earlier period in the history of Islamic theology. The fact that some of the proposed solutions were themselves criticized and reexamined by other Muʿtazilī theologians further shows that the argument from mutual hindrance was neither static nor monolithic within the Muʿtazilī tradition but rather was continuously reassessed for its coherence with the school’s core principles. In this regard, the objections raised did not lead Muʿtazilī theologians to abandon the argument from mutual hindrance; on the contrary, they prompted a reinterpretation of its premises and an effort to resolve the problems encountered within their own theological framework.

Therefore, the responses of Muʿtazilī theologians to objections against the argument from mutual hindrance were not motivated solely by the defense of a particular proof of the oneness of God but also reflected a broader concern for maintaining consistency among the various principles governing will, being capable by virtue of its essence, motive, and the evidential significance of possibility. The various solutions they proposed to these interconnected problems reflect this broader concern. At the same time, these discussions concerning will, motive, and the scope of divine power are also significant for divine infinity, since they directly concern whether divine will and power can be limited by any external factor.

This observation also calls for a cautious approach to the claims advanced by Sunnī theologians such as al-Nasafī and al-Juwaynī that the Muʿtazilīs were unable to rationally establish the oneness of God according to their own methodological principles and therefore held that the divine unity can only be known through revelation. The fact that Muʿtazilī theologians accepted revelation as proof of the oneness of God does not mean they believed the divine unity could be known only through revelation. Indeed, alongside the argument from mutual hindrance, Muʿtazilī literature contains various other rational proofs for the oneness of God, and these were revisited and critically reexamined by various theologians over time. For this reason, evaluating the Muʿtazilī approach to divine unity solely in terms of the argument from mutual hindrance or the objections raised against it would fail to adequately reflect the diversity of reasoning developed by the school to establish the oneness of God. Since this study has been limited to the problems arising in the formulation of the argument from mutual hindrance, a comprehensive and independent analysis of these other rational proofs in Muʿtazilī sources would further clarify both the epistemic basis on which the Muʿtazilīs grounded the divine unity and how these arguments were examined, refined, and transformed throughout their historical development.