In his Kashf, the philosopher Ibn Rushd (d. 595/1198) reaches a crushing verdict about the centuries-old theological tradition: the practitioners of kalām might have been right in their insistence that Islam's fundamental religious dogmas have to be subjected to rational investigation and reason-based proof. Yet, their enterprise failed. For instance, the method employed by the mutakallimūn to prove that the world is God's creation is, in Ibn Rushd's estimation, “an obscure method … that is not a proof, nor effective, nor certain” (Muḥammad b. Aḥmad Ibn Rushd, al-Kashf ʿan manāhij al-adilla fī ʿaqāʾid al-milla, ed. Maḥmūd ʿĀbid al-Jābirī, Beirut: Markaz Dirāsāt al-Waḥda al-ʿArabiyya, 1998, p. 103). All that the mutakallimūn achieved was creating confusion among themselves and the rest of society.

Ibn Rushd, the philosopher, might be accused of a certain bias against the rival kalām tradition; however, classical kalām works bear witness that their authors were far from unanimous agreement on which methods and proofs were valid, and which concepts and tenets should be upheld. Laura Hassan's Ashʿarism Encounters Avicennism: Sayf al-Dīn al-Āmidī on Creation highlights just how fiercely debated these questions were. Based on her PhD thesis at SOAS University of London, Hassan's book seeks to contextualize the thought of a post-Avicenan luminary, al-Āmidī (d. 631/1233), who appears as a “puzzle” (p. 1) since he authored works of both Ashʿarī kalām and Avicennan falsafa. The “major theological issue of the creation of the world” (p. 4), traditionally the site of a clash between these two very different paradigms, provides her with the opportunity to investigate “the nature and extent of the philosophical influence on al-Āmidī's thought … [and] the extent to which al-Āmidī endorses the methods and doctrines of classical Ashʿarism” (pp. 3–4).

Hassan's study is insightful in several respects: it traces significant developments in the doctrines, concepts, and methods championed by al-Āmidī, who started his intellectual career as an ardent defender of Avicennism, in order then to become a staunch adherent of Ashʿarism. Yet, this shift of allegiance meant neither that al-Āmidī came to reject all aspects of Avicennism, nor that he simply accepted all aspects of the Ashʿarī tradition which he inherited from his predecessors. Al-Āmidī's works bear witness to a constant process of negotiation and deliberation. This insight reached by Hassan's book about al-Āmidī's intellectual development confirms those reached by several other publications about other post-Avicennan practitioners of kalām, which speak not without reason of the emergence of a “philosophical theology” (e.g. Ayman Shihadeh, “From al-Ghazālī to al-Rāzī: 6th/12th century developments in Muslim philosophical theology”, Arabic Sciences and Philosophy 15, 2005, 141–79; Frank Griffel, Al-Ghazālī's Philosophical Theology (Oxford, New York: Oxford University Press, 2009)). Hassan's conclusion that “It appears that a thinker of al-Āmidī's era was no longer bound to a straightforward commitment to the approaches of either of the traditions of philosophy or theology. … intellectuals of the time had more complex work to do” (p. 286) sums this up.

The question of the origin of the world and its relation to God was without any doubt one of the most debated problems among classical Islamic thinkers, and its significance was matched by the perceived need to clarify a host of concepts and considerations relevant to the problem. This is why Hassan's investigation of al-Āmidī's thought on creation stretches over eight whole chapters. As expected of studies that seek to contextualize a given thinker's thought, much of Hassan's book has the purpose of setting the proverbial stage: chapter 2 discusses conceptions of creation in al-Āmidī's intellectual milieu, ranging from Ibn Sīnā to early and late classical Ashʿarīs. The following chapters, which discuss in detail certain considerations relevant to the broader problem of creation, contain ample reference to al-Āmidī's predecessors, particularly Ibn Sīnā, al-Ghazālī, al-Shahrastānī, and Fakhr al-Dīn al-Rāzī. This gives Hassan the opportunity to discuss the elements of al-Āmidī's thought against the background of his predecessors, to point out continuities as well as changes, and to highlight how al-Āmidī explicitly engaged with aspects of the traditions he inherited.

It goes beyond the scope of this review to comment on each of the themes relevant to the issue of creation discussed by Hassan over the course of the chapters. Suffice it to say that these include the varying conceptions of possibility and necessity held by Ibn Sīna, on the one hand, and certain post-Avicennan mutakallimūn on the other (chapters 3 and 4); as well as disputes over whether Ashʿarī physical theory with its ontology of atoms, bodies, and accidents or Avicennan hylomorphism better describes reality (chapters 5 and 6). The most insightful chapter is probably the final one (chapter 8), which brings together all the various aspects previously discussed and shows how they play out in al-Āmidī's doctrine of creation. To mention just two examples, Hassan illustrates a break with traditional Ashʿarism when al-Āmidī abandons the doctrine of creatio ex nihilo as the premise of the proof that the world is dependent on God. Instead of arguing that the world is originated, and that it therefore requires an originator, al-Āmidī (like some post-Avicennan mutakallimūn before him) adopts an Avicennan method, which establishes the world's dependence on God through the concepts of possibility and necessity. This changed approach is probably linked to al-Āmidī's worry, as Hassan suggests, that the traditional method based on atomism is problematic, as it cannot answer to the Avicennan challenge of immaterial entities.

What is more, according to Hassan's analysis, while al-Āmidī keenly defends the traditional Ashʿarī conception of God as a powerful, volitional agent, he breaks with his predecessors’ method. Hassan argues that “his analysis of the relationship between the necessary and possible of existence provides him with sufficient evidence of God's voluntary agency” (p. 232) and stresses “the total absence of reference to the origination of the whole world from nothing in support of the free and voluntary nature of its cause” (p. 240). It seems to me that, in this specific regard, Hassan's analysis of al-Āmidī's break with traditional Ashʿarī methods of proof might go a bit too far. This is so as al-Āmidī does in fact invoke “origination” in the passage analysed by Hassan. He writes: “if the cause of the originated things (ḥawādith) were a cause by essence and nature, then…” (ʿAlī b. Abī ʿAlī al-Āmidī, Abkār al-afkār fī uṣūl al-dīn, ed. A.M. al-Mahdī, 5 vols, Cairo: Dār al-Kutub al-Miṣriyya, 2010, vol. 1, p. 243). Admittedly, here it is not explicitly the origination of the whole world; but in the following sections, which are dedicated to proving God's power and volition, al-Āmidī explicitly invokes the origination of the whole world, opening both sections with “if the origination of the world has been established…” (Al-Āmidī, Abkār al-afkār, vol. 1, p. 280 (power) and p. 305 (volition)).

However, this should not take away from the fact that Hassan's book is a valuable and certainly very insightful contribution to furthering our understanding not only of al-Āmidī's thought on creation in particular, but the intricate ways in which different intellectual traditions in classical Islam reacted to each other.