1. Al-Bāqillānī’s Kitābal-Tamhīd and al-Inṣāf and the Proof of God’sExistence
2. The First Argument Based on the Analogy Between the shāhid and the ghāʾib
3. The first argument involves the following reasoning: “the proof (al-dalīl) for this is that something written (al-kitāba) necessarily has a writer, the form (al-ṣūra) a fashioner, and the building (al-bināʾ) a builder.” Al-Bāqillānī then continues: “we would not doubt the ignorance of him who told us that something written came about—but without a writer […]. It is, in consequence, necessary that the forms [contained in] the world and the movements of the spheres are connected with a creator (mutaʿalliqa bi-ṣāniʿ) who created them” (Al-Bāqillānī, Kitāb al-Tamhīd, 23). Al-Māturīdī, too, made use of the very same notion of a writing and its author, yet with the objective of arguing on its basis for the originatedness of the world (Abū Manṣūr al-Māturīdī, Kitāb al-Tawḥīd, 14).

1. The Second Argument Based on the Earlier and Later Occurrencesof Things
2. Al-Bāqillānī then presents a second argument in support of his assertion that the originated world exists due to an originator. This argument focuses on “the earlier occurrence (taqaddum) of some originated things than others as well as the later occurrence (taʾakhkhur) of some of them than others.” Their occurrence at an earlier or later point in time cannot be “due to the thing itself (li-nafsihi) or depend on its kind (jinsihi),” al-Bāqillānī stresses, as this would mean that all things of the same kind would have to occur simultaneously. This proves, he then concludes, “that there is for it one who makes it occur earlier and who brings it into existence according to his will (maqṣūran ʿalā mashīʾatihi)” (Al-Bāqillānī, Kitāb al-Tamhīd, 23).

The Third Argument Based on the Different Forms and Shapes of Things

The section on “the affirmation of the creator” finally contains a third argument. Al-Bāqillānī argues that “every single body in this world is receptive (qubūl) to a structure (tarkīb) different from the one it has.” A square, for instance, could well have been a circle instead. Parallel to the aforementioned case of the earlier and later occurrence of things, al-Bāqillānī now argues that “the specific, particular form by which it is particularised (ikhtaṣṣa) is due to the thing itself or due to its receptiveness of it.” If the former were the case, it would follow, for al-Bāqillānī, that all possible shapes would be present in the body at the same time. Since this is evidently absurd, he concludes, this proves that “whatever has a form only receives it from one who composed (muʾallif) and intended (qāṣid) it this way” (Al-Bāqillānī, Kitāb al-Tamhīd, 23–24). According to al-Bāqillānī’s reasoning, it would be equally likely for fire to be hot and cold, for its actual hotness is not due to itself and is simply an accident inhering in its body (that is, its essence or “body-ness”) that could have been replaced by the accident of coldness (if God had so chosen, that is). This position would later be vehemently opposed by Ibn Sīnā (d. 427/1037), who assumed the existence of natures of things, which explain why things are the way they are and that they could not have been different in all conceivable ways.

On Ibn Sīnā’s theory of secondary causality in nature, see:
Richard M. Frank, Creation and the Cosmic System: Al-Ghazālī & Avicenna (Heidelberg: Carl Winter, Universitätsverlag, 1992); Frank Griffel, Al-Ghazālī’s Philosophical Theology (Oxford, New York: Oxford University Press, 2009), Chapter “The falāsifa’s View of Creation by Means of Secondary Causality” (133–141); Robert Wisnovsky, “Final and Efficient Causality in Avicenna’s Cosmology and Theology,” Quaestio 2 (2002): 97–123; Gad Freudenthal, “The Medieval Hebrew Reception of Avicenna’s Account of the Formation and Perseverance of Dry Land: Between Bold Naturalism and Fideist Literalism,” in The Arabic, Hebrew and Latin Reception of Avicenna’s Physics and Cosmology, Scientia Graeco-Arabica 23, ed. Dag Nikolaus Hasse and Amos Bertolacci (Boston, Berlin: De Gruyter, 2018), 269–311; Jean-Marc Mandosio, “Follower or Opponent of Aristotle? The Critical Reception of Avicenna’s Meteorology in the Latin World and the Legacy of Alfred the Englishman,” in The Arabic, Hebrew and Latin Reception of Avicenna’s Physics and Cosmology, Scientia Graeco-Arabica 23, ed. Dag Nikolaus Hasse and Amos Bertolacci (Boston, Berlin: De Gruyter, 2018), 459–534.

In the Kitāb al-Tamhīd, al-Bāqillānī states that God described Himself with the words “I am creator” (innī khāliq). In the Inṣāf, al-Bāqillānī emphasizes that “He called Himself creator (khāliq) and everything besides Him created.” He then mentions Q. 13:16, “Have the partners (shurakāʾ) they assigned to God created anything like His creation? Is their creation indistinguishable from His? Say, ‘God is the Creator (khāliq) of all things[…]’,” and comments that in this verse “God refuted the unbelievers when they associated partners with Him in creation (shurakāʾ fī al-ikhtirāʿ).” A number of other Qur’anic verses are adduced by al-Bāqillānī in support of the claim that “there is no creator (khāliq) other than Him,” such as Q. 16:20, “Those they invoke beside God create nothing; they are themselves created.” Al-Bāqillānī, finally, also notes that God has made “belief in Him” (al-īmān bihi) obligatory upon all humans. Belief in God means “assent (al-taṣdīq) by the heart that He is God (Allāh), the one, the unique […], the creator (al-khāliq).”
Admittedly, all these statements appear in sections other than that on “the affirmation of the creator” and they deal with various aspects which, however, all relate to God’s role as creator: al-Bāqillānī mentions God’s self-description as creator (“I am creator”) in the Kitāb al-Tamhīd as part of a discussion about God’s attributes of action (ṣifāt al-afʿāl) and attributes of essence (ṣifāt al-dhāt) and introduces it as an example of the former category of attributes. His remark that “He called Himself creator” in the Inṣāf is part of a discussion about the createdness/uncreatedness of the Qur’an. Q. 13:16 is mentioned in the context of al-Bāqillānī’s defense of the position that God creates human actions, including belief and unbelief (that is, the doctrine of kasb or acquisition). And Q. 16:20, finally, appears in support of the claim that God alone provides for humans. These statements, however, all draw attention to the importance al-Bāqillānī assigns to upholding that God is to be described as creator, not only of the world itself, but of the occurrences in it, too. The proof that God indeed is to be described with this attribute is nothing else than “the affirmation of the creator,” where al-Bāqillānī establishes that the originated world came about due to an outside cause (that is, it does owe its existence to another, rather than being self-sufficient) so as to be able to ascribe it to God.

Creation as Proof of God’s Existence?
Among the items of knowledge which humans are obligated to know by God, al-Bāqillānī also mentions the following: he has to know that the first thing God has made obligatory upon all humans is speculation about His signs, pondering over the things He has power over (maqdūrātihi), and reasoning towards Him based on the traces (āthār) of His power and the witnesses (shawāhid) to His rubūbiyya, for He is not known necessarily and not observable by the senses; His existence and being (wujūduhu wa-kawnuhu) are only known by the compelling proofs contained in His deeds (Al-Bāqillānī, al-Inṣāf, 21). Al-Bāqillānī here unequivocally states that it is God’s existence which is known on the basis of creation. ʿAbd Allāh seems to have understood this kind of statement as an explanation on al-Bāqillānī’s part for why in the section on “the affirmation of the creator” he presents—as ʿAbd Allāh sees it—a number of cosmological arguments for God’s existence (“these are the proofs al-Bāqillānī presents to affirm the existence of God (wujūd Allāh)”): it is “because the mutakalimūn did not all agree that God is known necessarily.” In the Inṣāf he explains that were God to resemble His creation it would entail that He is a “composed body” (jism muʾallaf) just as the bodies making up this world which are composed from atoms (Al-Bāqillānī, al-Inṣāf, 31).

Al-Shahrastānī (d. 548/1153) reports about this position held by the mutakallimūn in his Nihāyat al-iqdām fī ʿilm al-kalām: “the ahl al-ḥaqq maintain that God does not resemble the created things and they do not resemble Him in any respect—nothing is like Him […]. The creator is neither an atom (jawhar), nor a body (jism), nor an accident (ʿaraḍ). He is neither in a place, nor in time. He is not receptive to accidents and is not the substrate of originated things” (Muḥammad b. ʿAbd al-Karīm al-Shahrastānī, Nihāyat al-iqdām fī ʿilm al-kalām, 103). Al-Bāqillānī states that humans need to make recourse to speculation and that “His existence and being are only known by the compelling proofs contained in His deeds.” Furthermore, even though God’s essence is the object of theological enquiry, al-Bāqillānī stresses that humans are prohibited from speculating about it. Rather, they are obligated to arrive at knowledge about God’s essence (which includes classifying His kind of existence) by inference from creation: “since it is the case that speculation is an obligation, humans [lit.: al-mukallaf] have to speculate and ponder over the things God created (makhlūqāt Allāh), not over God’s essence (dhāt Allāh).” The proof of this is, al-Bāqillānī suggests, that in the Qur’an God speaks—with praise, one might add—about those {who reflect on the creation of the heavens and the earth [i.e. Q. 3:191]}. “He did not say: on the creator,” al-Bāqillānī points out. The Qur’anic story of Moses’ conversation with Pharaoh is adduced as further evidence of the requirement to make speculation about creation the basis of statements about God’s essence, and not to think of investigating God’s essence itself.