Peter Adamson is a firm believer in philosophy’s importance. “Don’t let anyone tell you that philosophy is useless,” he exhorts in his new book (41). Adamson sets out to show in this book that medieval philosophy in particular offers striking reflections on a topic with profound implications for the present day: our trust in experts and authorities. Considering the apparent “crisis of authority that has come to dominate the political scene over the past years,” he insists that we can learn much from medieval thinkers about how “to make intelligent use of knowledge that lies beyond our own competence” (xi).

In a work that is thoughtful, lucid, and concise, Adamson makes a compelling case for this claim. The book focuses primarily on medieval attempts to understand how we gain knowledge and form our beliefs, and what the proper role of authority figures ought to be in that process. Adamson is an expert on medieval Arabic philosophy, and it is the debates within that tradition that provide the initial impetus for his theme in the opening chapters. Many of those discussions will be familiar to specialists, but Adamson widens the lens through which they are viewed. Throughout the book, he ranges over a number of examples from Judaism and from Christians in Byzantium and the Latin West, and across the centuries from the fifth to the sixteenth. Placing figures from these different traditions (and eras) in continual--and often unexpected--conversation with each other, Adamson successfully highlights the richness and breadth of medieval philosophy.

He does not tell a single, chronologically unfolding story of philosophical debates about reason, belief, and authority. With the book’s origins in two sets of lectures, the 2019 Conway Lectures at Notre Dame and the 2020 Carlyle Lectures at Oxford, its seven chapters cohere to varying degrees. Adamson asserts at one point that what he “wants to show in this book is that we can learn something about blind acceptance, and how to avoid it” from medieval philosophy (2). In reality, this is the focus only in the first few chapters, which more closely hew together in a distinctive arc revolving around the tension between independent judgments and the reliance on traditions and their authoritative figures and texts. The remaining chapters, though, are intriguing in their own right as reflections on how medieval thinkers understood authoritative tradition, human nature, and the life of the mind.

In his opening chapter, Adamson introduces his readers to two concepts which will propel the first part of the book, concepts which emerge from Islamic debates about belief and authority: taqlīd and ijtihād. Adamson derives their meaning from discussions of them in legal and theological contexts: he definestaqlīd as “reaching judgments on the basis of someone else’s authority” and of ijtihād as “effortful exertion” to personally understand the grounds for one’s judgments (3). With clear implications for religious believers, the proper relationship between taqlīd and ijtihād nonetheless affects every realm of knowledge, for one must always decide when to seek out truths for oneself and when to rely on others who have gone before. Debates between Mu‘tazilites and Ash‘arites form a large part of the chapter, but Adamson draws on a variety of Islamic sources to show a range of attitudes towards taqlīd and recognition of the difficulty--and indeed undesirability--of expecting everyone to think everything out for themselves. Often, philosophers fell back on a dichotomy between those encouraged to engage in ijtihād (usually the philosophers themselves) and those allowed to rely on taqlīd. Adamson calls this the creation of an “epistemic elite” (xiv), and he poses important questions about it: is it necessary? how does one qualify for it? what is the alternative?

Chapter 2 offers one explanation for the rise of this philosophical elite, namely the notion that true knowledge was very difficult to obtain. Exploring the influence of classical philosophy on medieval epistemology, Adamson concludes that the very high standard for knowledge set by ancient Greek thinkers actually prompted deep concerns--across the medieval philosophic world (and in ways that, as he shows, prefigure early modern philosophy)--about whether or not one could have certain knowledge. The question was not just, how do you know something? but rather, how do you know that you know something? We see these questions asked by Islamic philosophers such as al-Kindī and al-Fārābī, by Jewish philosophers such as Saadia Gaon and Maimonides, and--under the influence of Avicenna in particular--by fourteenth-century Latin scholastic thinkers such as John Buridan and Nicholas of Autrecourt.

Chapter 3 proposes a solution to the dilemmas surveyed in the previous chapters, a solution Adamson calls “justified taqlīd” (44). He finds this compromise articulated in al-Ghazālī, who put forth the idea that “we ought to submit to an authority in some domain but only after understanding the domain well enough to satisfy ourselves that these authority figures have genuine expertise” (44). To show the utility of this concept, Adamson examines four texts from the twelfth to the fourteenth centuries written in dialogue form in which the characters argue over the qualities of different religious faiths. He chooses two by the Jewish philosophers Judah Hallevi and Shem Ṭov ben Joseph Falaquera and two by the Latin Christians Peter Abelard and Ramon Llull. Adamson notes how the use of “justified taqlīd” helps some of the authors (primarily Hallevi) move beyond either “uncompromising rationalism” (60) or simple reference to revelatory authority. Instead, the protagonists must show why one would have good reason for believing their respective authorities. Adamson clearly approves of this manner of discussion and debate, and he moves from the descriptive to the prescriptive: “when we resort to taqlīd we should do so in the way recommended by al-Ghazali: still think for ourselves, by thinking about which authority is worth believing” (60). This is the “better” approach to authorities that “we need” (19).

Adamson is refreshingly forthright about the lessons one can learn from the past, though his admonitions are understated, never detracting from his patient descriptions of complicated material. By the end of the third chapter, he has brought his readers to understand the significance of “justified taqlīd,” both in the Middle Ages and, it would seem, in our current age. With this as one of the stated goals of his book, it is a little surprising that he does not expand more explicitly his discussion of the concept in the chapters that follow, by considering, for instance, descriptions of it in Byzantine thought or Latin scholasticism, or, more significantly, examples of it in discussions of the relationship of individual to community. The latter topic is one Adamson himself raises early on (18-19), rightly implying that “justified taqlīd” would require continual assessment of that relationship. Nonetheless, while Adamson takes a somewhat different route in Chapters Four and Five, he does highlight fruitfully a key element of “justified taqlīd”: how one might depend on a particular authority and offer reasons for doing so. Thus, he hones in on the ways in which medieval philosophers in multiple philosophic traditions relied on ancient pagan (i.e., Greek) writers, especially Plato and Aristotle, and how they defended that reliance.

At the end of the fifth chapter, Adamson turns to “another story” (99), one that highlights a different aspect of medieval considerations of authority, that of women authors. In some ways a return to his much earlier discussion of an “epistemic elite,” the topic is certainly worthy of consideration, but with no references to the Arabic world and with the majority of examples drawn from the rhetorical tropes of late medieval Latin Christian writers, this particular essay seems least imbued with Adamson’s usual expertise and insight, and it is more difficult to locate it in relation to what has come before. One particular argument that does stand out, though, is Adamson’s proposal that the use of eloquence in Renaissance humanism created “a new standard for measuring intellectual ability” (112), one that made it more possible for women to be considered authorities in their own right.

In his closing essay, Adamson again reflects on the “epistemic elite” by examining how rationality became for medieval philosophers the distinctive marker of human nature. Drawing first on treatises by Islamic thinkers (al-Rāzī and Miskawayh) and then Thomas Aquinas, Adamson extends his theme into more political waters when he looks at how certain assumptions about rationality affected debates over the status of natives in the Americas. He determines that the belief in an epistemic hierarchy easily supported a political hierarchy with often bleak consequences. This turn to politics at the end of the book is more gesture than argument, as Adamson himself acknowledges: in his Introduction, he proposes it as an area for further exploration (xv). He has laid out well a path which that exploration might take.

Adamson offers no conclusion to his story of the relationship between authority and belief. But his illuminations of various facets of this theme are highly stimulating. Specialists in medieval philosophy will certainly benefit from the myriad and insightful ways Adamson brings thinkers from different traditions into conversation with each other on familiar topics. Scholars will likely find places where more systematic comparisons of particular traditions could have been made, since certain chapters deal more with some traditions than with others. For instance, what happens if Adamson’s discussion of the relationship of belief and authority in Islamic legal and theological contexts is placed alongside similar considerations which develop in the same two contexts in the Latin Christian world of the eleventh and twelfth centuries? Or, how might twelfth-century Christian Platonism help answer Adamson’s questions about the rise of Islamic interest in Plato at the same time? How do the various readings of Avicenna and Averroes in these different philosophic traditions shape their answers to the topics at hand? Yet the emergence of questions such as these is less a critique than a tribute to Adamson’s accomplishments in provoking them within the space of this modestly-sized work.

Furthermore, Adamson has transformed the concerns of subtle and often highly technical treatises into arguments both accessible and consequential. He has written a book which can be read fruitfully not only by medievalists of all disciplines, but also by anyone interested in the philosophic contributions of the past. (Adamson has clearly intended it as such, since the book is light on scholarly apparatus: a Further Reading section stands in for a Bibliography, while the endnotes are kept to the essentials.) Throughout the book, Adamson is open to the ways in which rationality and religious faith were intertwined, and he underlines how medieval discussion and debate on belief and authority offer considerations to be taken seriously. Treating medieval philosophers and their concerns fairly but by no means uncritically, Adamson not only brings those concerns into the present day but he also displays in his own authorial work how an expert can become an authority one might trustingly turn to for knowledge.