Short but ambitious, Sarah Stroumsa's Andalus and Sefarad should be required reading for anyone interested in the subjects identified in its subtitle—On Philosophy and Its History in Islamic Spain—for students of the medieval Islamicate as a whole, and for those concerned with the difficulties of charting premodern intellectual exchange in general. Stroumsa offers a sophisticated and careful perspective on the relationships between competing and mutually sustaining religious communities. Stroumsa's method is to thoroughly engage earlier scholarship, while deploying her own “integrative, multifocal approach” (p. 168) to the history of “this peninsula,” as its denizens proudly called it.

This book is rich with insights into specific political and intellectual movements, but most compelling is Stroumsa's demonstration that the histories of Muslim and Jewish scholars of al-Andalus are best told as a single, “unitary narrative” (p. xi). This argument, perhaps Stroumsa's most far-reaching contribution, appears in the introductory framing chapter. Building on recent studies of Muslim-Jewish interactions and implicitly engaging theoretical analyses of interreligious exchange and community formation, Stroumsa argues that—unlike in other geographic regions—theology and philosophy in al-Andalus should be examined as a single coherent unit, not as disparate and competing “schools.” Much like Stroumsa's earlier Maimonides in His World: Portrait of a Mediterranean Thinker (Princeton, NJ: Princeton University Press, 2009), the work under review scrutinizes both the citation practices of medieval Arabic authors, which inevitably mask their wide reading, and the (frequently forgotten) personal interactions between scholars. In reality, she insists, in this cultural world Muslim and Jewish elites formed a shared community that far surpasses the “symbiosis” terminology of Shelomo Dov Goitein. (Christians were relatively marginal during this period.) Only by accounting for the writings of both Muslims and Jews, Stroumsa maintains, can one follow the development of Andalusian “speculative thought” (p. xi; her definition of philosophy, which she uses more broadly than the medieval concept of falsafa or even contemporary investigations of that Arabic term).

In each subsequent chapter, Stroumsa presents case studies for how scholars might approach al-Andalus with these “integrative” goals in mind. The first and second chapters in particular rediscover social and speculative trends that have been obscured over time, intentionally or otherwise. In the first, Stroumsa traces 10th-century efforts by Muslims and Jews to establish al-Andalus's intellectual bone fides. While these efforts were somewhat aborted among Muslim writers by the censorship program of the Umayyad vizier al-Mansur, Jewish intellectual activity in the 11th century flourished. This suggests, Stroumsa argues, that the Jewish community managed to escape al-Mansur's watchful eye, preserving books and knowledge that would later be used to reconstitute a variety of fields in al-Andalus. Stroumsa further investigates the writings of Ibn Masarra, suggesting that certain aspects of his thought (e.g., letter speculation and the term ism for “the hidden name” of God) might be explained by contact with Jews during his time in north Africa and in particular with Jewish commentaries on the cryptic Sefer Yesirah. The Jewish-to-Muslim flow of ideas, she admits, was “much rarer” than the transfer of knowledge in the other direction (p. 53); this historical reality, however, does not detract from her larger project of reading the history of these two groups side by side. (On the topic of speculative writing on letters one might add the tantalizing report that the 12th-century Andalusian Talmudist Joseph Ibn Migash wrote about the “secrets” of the Hebrew letters; see Israel Ta-Shma, Studies in Medieval Rabbinic Literature [in Hebrew] [Jerusalem: Bialik Institute, 2004], 2:56.) Similarly, Chapter 2 demonstrates how scholarship that crosses religious boundaries can aid in exploring lesser known schools of thought, in this case, Muʿtazilism, Ẓahirism, and Karaism. Stroumsa's view is that, in al-Andalus, these groups were far smaller than often assumed, apart from some shadowy Karaite communities in the north. Even as many thinkers engaged such ideas, they hardly constituted “schools” in any sense of the word. Stroumsa cautiously reexamines medieval (and modern) lists of alleged adherents of these approaches, reaching far narrower conclusions than those of Maribel Fierro and Camilla Adang, for example.

The remaining chapters address better known phenomena of medieval Andalusia. The third establishes that Muslim and Jewish philosophers shared a common curriculum, had similar elitist attitudes, and felt a common sense of isolation from their coreligionists. Stroumsa reasons that many more interreligious friendships must have developed among the philosophical class than are recorded, as philosophical thinking was intelligible to various men, “despite their differences” (as Ibn Bajja wrote; p. 100). This socio-historical examination provides a crucial pivot for Stroumsa's argument, buttressing her hypothesis about the citation practices of this small but productive scholarly collective.

In the fourth chapter, Stroumsa contrasts the suspicious attitude of the Maliki ʿulamaʾ towards Neoplatonism with its “utterly disproportionate” embrace by Andalusian Jews in the 11th and early 12th centuries (p. 120). By utilizing Neoplatonism as her primary lens, rather than “Muslims” or “Jews,” Stroumsa succeeds in telling a robust narrative of Andalusian reactions to this Fatimid/Ismaʿili–inspired school of thought. To her mind, political concern with the Fatimids on the part of the Maliki elite in al-Andalus explains, on the one hand, the negative reaction to Ibn al-Sid al-Batalyawsi among his fellow Muslims and, on the other, his very positive reception among Jews (who translated his Kitab al-Dawaʾir into Hebrew no fewer than five times!). The history of Andalusian Neoplatonism thus acts as a synecdoche for Stroumsa's larger call to reconsider Islamic and Jewish writers in tandem.

The final chapter turns to Almohad-era Aristotelianism, which Stroumsa characterizes as a “neo-orthodoxy” (p. 124). Stroumsa is skeptical about the role that the Almohads played in invigorating this movement and justifiably minimizes the Aristotelian elements of Almohad Ashʿarism. Al-Marrakushi's 13th-century report of a meeting between Averroes and the Almohad caliph—which many scholars have accepted as historical fact—is here downgraded to a “fuzzy” account of a get-together that “probably never took place” (p. 141). Even if it did, Stroumsa shows that Averroes had already developed a program of Aristotelian commentaries prior to the caliph's supposed intervention. She nevertheless proposes that Almohad attitudes informed many developments of the 12th century. For example, she asserts that their “naturalist fundamentalism” encouraged a reconsideration of medical knowledge and spurred a long-dormant “revolution” that rethought Ptolemaic astronomy (p. 156). And as in Maimonides in His World, Stroumsa argues that Almohad disdain for furūʿ (branches or positive law) and their return to uṣūl (roots or legal principles) informed the legal projects of both Maimonides and Averroes.

It should, however, be noted that early Almohad legal theory (which I regard as closer to Maimonides's views) was itself rooted in Maliki thinking, which had long deemphasized furūʿ for the sake of uṣūl, partly as a reaction to Ibn Hazm, as Fierro and others have shown. The extremism that al-Marrakushi ascribed to the Almohad caliph Abu Yusuf Yaʿqub (p. 79)—who only reigned beginning in 1163—may not in fact hold for the Almohad founder Ibn Tumart, as both he and Averroes were committed to the Maliki tradition in various idiosyncratic ways. Indeed, Ibn Tumart, Averroes, and Maimonides each responded to longer trends in Maliki jurisprudence, akin to the Almohad invigoration of non-Ptolemaic astronomy described by Stroumsa; their work did not constitute complete breaks with Almoravid-era authorities and attitudes.

This book is carefully copyedited and beautifully produced. One small caveat: Princeton University Press apparently prefers to omit the year of publication in footnotes. I found that this hindered my appreciation of Stroumsa's close reading of 20th-century historiography, as I had to check the chronology of some lesser-known scholars in the bibliography.

A more substantive critique pertains to two broader questions. First, as Stroumsa observes (p. 13), the interreligious exchange that marked medieval al-Andalus was certainly not unique in the Islamic world (10th-century Baghdad being perhaps the other well-trodden example). For reasons that pertain to the memory of the Spanish exile and to modern German-Jewish emancipation and religious reform, the “Golden Age” of Islamic Spain has long held pride of place within the Jewish imagination. Nevertheless, I was left wondering just how unique Stroumsa feels the peninsula really was. Second, and relatedly, Stroumsa only briefly touches on Marshall Hodgson's notion of the “Islamicate.” Given that this concept undergirds much of her thinking and that it has recently been subject to sustained and thoughtful evaluation in Shahab Ahmed's What is Islam? The Importance of Being Islamic (Princeton, NJ: Princeton University Press, 2015), Stroumsa's work would have benefited from using her case studies to evaluate Ahmed's probing appraisal of Hodgson. While the large methodological problems raised by these scholars perhaps cannot be resolved, it is precisely Stroumsa's kind of historical investigations that are needed to hone scholarly evaluations of the Islamic world writ large.