The publication of Sohaira Siddiqui's monograph is a long overdue event in Islamic studies. It ends the inexplicable absence of a scholarly book in English treating a towering thinker of pre-modern Islam, Imām al-Ḥaramayn al-Juwaynī (d. 478/1085). Besides filling this major gap, this book offers three fundamental contributions to the study of Islam.

First, this book serves as a model for future studies on prominent figures of Islamic intellectual history such as al-Ghazālī and, hopefully soon, al-Māwardī. Rather than approaching al-Juwaynī as an Ashʿarī theologian or a Shāfiʿī jurist, or relying on a single influential text, the book seeks to identify his intellectual project by examining carefully selected works including the Shāmil, Irshād, Burhān, Talkhīṣ, and Ghiyāthī. Siddiqui's inclusion and exclusion of titles reflects her command of al-Juwaynī’s texts, which span multiple disciplines, and her comprehensive understanding of his intellectual and socio-political context.

The book's second major contribution is to bring the disciplines of theology, law, and political thought into one coherent discussion. Siddiqui accomplishes this skilfully by highlighting al-Juwaynī’s twofold preoccupation with certainty and continuity in his treatment of three areas: reason and revelation, the firmness of the sources of law, and the imām’s political role in society and the consequences of his absence. She argues that the Muʿtazila-Ashʿarī theological debates and clashing epistemologies, and the precarious and fluid political situation of al-Juwaynī’s time produced a recurrent tension between his concern with attaining epistemically certain knowledge in theology and law, and the wish to preserve the community's social and religious continuity. As such, a central accomplishment of this book is the linking of al-Juwaynī’s intellectual and political projects.

The book's third contribution follows intuitively from the second. Siddiqui conceives of the sharīʿa as a dialectical nomos in a novel and stimulating way and, arguably, al-Juwaynī’s thought helps her provide a compelling case. Through a meticulous examination of al-Juwaynī’s ideas in various interlocked theological, legal, and political texts, Siddiqui explains how his conception of the sharīʿa acted as the main guarantor of social order in every political eventuality. As such, the sharīʿa “is a dialectical mechanism of governance influencing society through the production of legal norms and responding to sociopolitical conditions” (p. 283).

Part 1 (chapters 1 and 2) does a good job of portraying Nishapur, where factionalism developed along a mesh of theological, legal, and socio-political fault lines that were exacerbated by the Seljuks’ arrival. In this cosmopolitan world, al-Juwaynī was exposed to diverse theological, legal, and philosophical influences. Forced to flee Nishapur, he spent five years between Baghdad and the Ḥijāz before returning, at the behest of Niẓām al-Mulk, to teach kalām and uṣūl al-fiqh at the Niẓāmiyya school. This eventful life led to al-Juwaynī’s dual concern with political stability and epistemically sound religious doctrine, i.e. continuity and certainty.

Part 2 (chapters 3 and 4) examines al-Juwaynī’s epistemology. Chapter 3 provides an absorbing overview of the opposing Muʿtazila-Ashʿarī epistemological views on the limits of reason and centrality of revelation, and the ability to attain certainty in legal and moral matters. Chapter 4 treats al-Juwaynī’s assertion, in a substantial departure from the standard Ashʿarī position, that exhaustive reasoning (naẓar) can lead to practical certainty in concluding enquiries. For Siddiqui, al-Juwaynī’s fundamental contributions to Ashʿarī epistemology provided the cornerstone for the decisive turn in Ashʿarī kalām that is generally attributed to al-Ghazālī and for later changes introduced by al-Rāzī.

Part 3 (chapters 5–8) investigates al-Juwaynī’s answer to legal uncertainty. Here, Siddiqui demonstrates a remarkable understanding of the influence of theology on Islamic legal discourse through her rigorous depiction of al-Juwaynī’s quest for epistemic certainty in the sources of fiqh and the derivation of resilient legal norms. Al-Juwaynī relies on his epistemological framework to establish conclusively the soundness of ḥadīth as a source of legal derivation. Furthermore, he defends ijmāʿ using novel and rational proofs rooted in customary practice to produce “practically-certain” legal derivation. Likewise, al-Juwaynī promotes qiyās and maṣlaḥa, the welfare of the Muslim community, to guide jurists whenever scriptural sources are inadequate. He conceptualizes religious knowledge as “the product of communal knowledge and practice” (p. 177).

Part 4 (chapters 9 and 10) treats the political thought articulated in the Ghiyāthī. Siddiqui posits that al-Juwaynī was the first Islamic thinker to forge a direct connection between epistemology and political thought. She draws on her previous discussions of his epistemology to demonstrate that he gave primacy to continuity, political stability, and the preservation of religion. By highlighting the Ghiyāthī’s conception of the sharīʿa as a dialectical nomos and guarantor of the community's continuity in the event of the collapse of political authority and institutions, the book advances a formidable challenge to the claim that pre-modern Islamic political thought was centred on rulers.

Of this exceptionally well-structured work, I can make only three complaints of substance. The first is that, for such an exhaustive book, the account of al-Juwaynī’s relationship with Niẓām al-Mulk is unsatisfactory and unoriginal. Since al-Juwaynī’s political project is one of her main enquiries, Siddiqui could have entertained the interesting conjecture, made by the editor of al-Ghiyāthī’s selected version, that al-Juwaynī may have incited Niẓām to claim the imāmate for himself. The second substantial complaint is of the insufficient treatment of al-Māwardī’s influence on al-Juwaynī. Both Shāfiʿī scholars lived in the Seljuk period, were exposed to similar influences, and faced comparable political concerns; most importantly, al-Māwardī is a main interlocutor in the Ghiyāthī. Although al-Juwaynī regularly critiques al-Aḥkām al-sulṭāniyya’s chapter arrangement and its lack of conclusive interpretations, several of the Ghiyāthī’s discussions are in fact in dialogue with and rooted in the Aḥkām. The third complaint pertains to the book's lack of coverage of al-Juwaynī’s explicit waiver of the necessity of Qurashī lineage for candidature to the imāmate. I find this omission unjustified since this waiver illustrates perfectly al-Juwaynī’s concern for political continuity and, therefore, would have buttressed Siddiqui's main argument.

There are other minor remarks: the book includes a few typos (pp. 50 and 86); the biographical information over-relies on al-Subkī’s Ṭabaqāt; al-Juwaynī’s exquisite Arabic writing style and his argumentation methods are not treated; and – despite some scattered paragraphs on the reception of al-Juwaynī’s ideas – the book does not examine his profound influence on subsequent jurists such as al-Qarāfī, Ibn ʿAbd al-Salām, Ibn Jamāʿa, and the Subkīs. But such observations are unreasonable expectations from a well-argued, well-written, and long-awaited book that fills a gap in Islamic studies and enables a greater understanding of the historical development of Islamic theology, law, and political thought.