The medieval English allegorical poem Piers Plowman described the birth of Islam as the result of a clever hoax. Muhammad, it asserted, was a former Christian who had made a failed attempt to become pope and then set off for Syria to mislead the innocents. He tamed a turtledove and taught it to eat grains of wheat placed in his ear. In a scene reminiscent of the enchantment of Melampus, the Greek oracle who was granted the ability to understand animal speech when his ears were licked by snakes, Piers’s Muhammad mesmerized audiences by having the bird fly down during the course of his preaching and appear to whisper in his ear. Staging a moment of revelation from God, the false prophet led men to misbelief by “wiles of his wit and a whit dowve.”

In the centuries following Muhammad’s death in 632, many Christians like William Langland, the author of Piers Plowman, sought to make sense of Islam in the terms and symbols of their own faith. Was it just another schismatic sect led by a great here­siarch, as Dante portrayed it in his Divine Comedy? Or was it an ancient form of chivalry, a Saracen code of ethics? Did Muhammad’s followers think him a god? The figure of the prophet-as-trickster found in Piers Plowman was not the most outlandish attempt to explain the origins of Islam. Medieval French chansons de gestes attributed a welter of fantastical qualities to the cult of “Mahom,” including a pantheon of minor deities superimposed from Roman mythology.

University chairs in Oriental studies began proliferating in Europe in the 17th century and were soon followed by the establishment of scholarly associations and academic journals. By the late 19th century, European knowledge of the languages, histories, and customs of Muslim societies had advanced significantly beyond the scope of medieval apologetics, but the interpretation of Islam through the lens of Christianity remained a central current of Orientalist scholarship. As Shahab Ahmed writes in a major new study, the consequences of this approach and its legacy have made it difficult for moderns—­scholars and laypeople, Muslims and non-Muslims alike—to grasp the “historical and human phenomenon that is Islam in its plenitude and complexity of meaning.” Coming to terms with Islam—“saying Islam meaningfully,” as he puts it—requires making ourselves sensitive to the “capaciousness, complexity, and, often, outright contradiction” that inheres within the broadest possible range of practices, beliefs, representational forms, metaphors, and objects associated with Islam.

Ahmed, a scholar of Islamic studies at Harvard, died this autumn at the tragically young age of 48. His book is a strange and brilliant work, encyclopedic in vision and tautly argued in the manner of a logical proof, yet pervaded by the urgency of a political manifesto. It is, in a way, all of these things. For those who knew him, the peculiar ambition of What Is Islam? will not come as a surprise, because Ahmed had been at work for years on a much-anticipated and controversial study about the formation of Islamic orthodoxy. The surprise is that What Is Islam? is not that book.

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Shahab Ahmed arrived at Harvard as an assistant professor in 2005. I was a doctoral student at the time and had heard most of the hagiographical accounts of his life that flowed through graduate-student circles. Fluent in many languages, Ahmed had lived in Singapore, England, Malaysia, and Egypt before coming to America for graduate school. After completing a doctorate at Princeton, he was admitted to Harvard’s prestigious Society of Fellows, where he spent three years before joining the Department of Near Eastern Languages and Civilizations. Mutual acquaintances spoke of his terrifying erudition and wit, sharpened by an unrepentantly refined British accent.

At Princeton, Ahmed had been a student of Michael Cook, the eminent historian. During his first year, he became interested in the “Satanic Verses” incident, an episode from early Islamic history in which the Prophet Muhammad was said to have mistaken some verses suggested by Satan as being part of the divinely revealed Koran. The topic intrigued him. Reading through the earliest sources, Ahmed found a widespread and untroubled consensus on the historical authenticity of the event, which stood in contrast to the doctrinal rejection that emerged centuries later. As he would argue in an award-winning dissertation, the early view of Muhammad as a man “subject to error and Divine correction” represented an outlook at odds with the later theories of prophetic infallibility. At the Society of Fellows, Ahmed began to expand his project into a larger study that would trace Muslim attitudes toward the figure of Muhammad through time and space, using the Satanic Verses problem as a way to explore the development of orthodoxy across the centuries. He assembled an enormous archive of legal, theological, literary, and historical sources on the subject in more than a dozen languages, drawn from manuscript libraries all over the world.

A faculty position interrupted the reverie of research. At Harvard, Ahmed swiftly established a reputation for teaching demanding graduate seminars. The first session of each course seemed designed to turn away as many curious students as possible. A fearsome syllabus front-loaded with hundreds of pages of reading each week, mainly in primary sources, was his deterrent of choice—and an effective one. While at Princeton, Ahmed had taken almost no courses, devoting all of his time to his own research. Michael Cook told me, “In those days, we had no rules obliging students to take courses—they were just expected to do so. Now, thanks to Shahab, we do have rules.”

Those who braved Ahmed’s courses were frequently stunned by the audacity of his expectations. He could be prickly, arrogant, contemptuous of poor preparation, and imperious. Despite this, I was enthralled by him. During my second year, I responded to an advertisement he placed for a research assistant. The job paid a pittance; about this, he was honest, but I convinced him to let me sign on. In his office were shelves filled with hundreds of identical orange file folders, each devoted to a different historical figure. This was the great collection he had put together on the Satanic Verses, an archive of everything ever said and written about the incident. Many of the folders contained transcriptions, in Ahmed’s impeccable Arabic cursive, of excerpts from manuscripts he had consulted in Istanbul’s great libraries and elsewhere in the Islamic world.

My task was to locate whatever information existed about the historical individuals in the archive, drawing on the extensive corpus of premodern biographical dictionaries and chronicles. For the rest of the year, I lived in a world of medieval authorities and onomastic wild-goose chases through the classical tradition. No figure in Ahmed’s archive was too obscure to escape his attention. We hunted for Transoxanian jurists, North African mystics, Andalusian grammarians, Iraqi logicians. Every scrap of opinion about the controversy buried in the great wall of orange files was somehow significant to Ahmed, and the most minor figures were often the most interesting. For months, I had no sense of what I was doing and how it fit into the larger project. Over time, however, things began to fall into place.

The story Ahmed was telling comprehended a tremendous braid of narratives, a pageant of contradiction and diversity in an intellectual tradition that spanned over a millennium. By historicizing the transformation in attitudes toward Muhammad’s prophetic mission, Ahmed hoped that his study might provoke an engagement with the tremendous resources of the past in confronting the questions of the present. How has Islamic orthodoxy been formulated over time, and how might it be reformulated today? As ambitious a thinker as he was, however, Ahmed also seemed to recognize that developing the full implications of his argument was a delicate business. This was the reason for the immensity of the book’s dimensions. As he confided to me one afternoon while we sifted through the mountains of references I had flagged, he was erecting a scholarly edifice so formidable that no one could challenge it.

Ahmed never fully completed the Satanic Verses project. The book grew larger in his mind, with the work accomplished occupying a correspondingly smaller portion of it. At some point, he entered a limbo between research positions and fellowships, during which time he embarked on a different project, co-authoring a book on heresy trials in the Ottoman Empire. When I saw him a year after I’d completed my degree, he seemed strangely happy, even accepting of the foregone conclusion that his chances of receiving tenure at Harvard looked impossibly slim. The new book was nearly finished; all that was left to write was an introduction.

Like the first project, however, that introduction grew larger and larger, absorbing all of its author’s attention and time. Eventually, it would become a 600-page tome with over a thousand footnotes. What Is Islam? is that book.

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When discussing the modern discipline of Islamic studies, Ahmed liked to complain that it was possible to earn a doctorate in this field from an Ivy League university without ever reading the Divan of Hafiz, the great 14th-century Persian poet. He describes that work in What Is Islam? as “the most widely-copied, widely-circulated, widely-­read, widely-memorized, widely-­recited, widely-invoked, and widely-­proverbialized book of poetry in Islamic history.” This was not merely a work of belles lettres, but a book that exemplified “ideals of self-conception…in the largest part of the Islamic world for half-a-millennium.” How could a modern student of Islamic civilization formulate an understanding of this subject without taking stock of such a work, and especially its treatment of wine drinking, erotic love, and the hypocrisies of self-righteous moralists? If Hafiz’s work is not Islamic, then what is?

This might as well be the central question of What Is Islam? The medieval world in which Hafiz’s Divan was a best seller was also a world suffused with the traditions of Avicennan rationalism, Sufi experiential mysticism, the celebration of figural representation, a taste for literary ambiguity, a distinction between public and private selves, and one between legal discourses and other measures of normativity. It was, in other words, a world crowded with variation and contradiction.

Such variety is everywhere to be found in the textual and material record of what Ahmed calls the “Balkan-to-Bengal complex,” the great belt of Muslim societies that stretched from southeastern Europe and Central Asia into North India between the 15th and late 19th centuries. This vast zone represented “the most geographically, demographically, and temporally extensive instance of a highly-articulated shared paradigm of life and thought in the history of Muslims—it is, demographically, spatially, and temporally, an (if not the) historically major paradigm of Islam.” To answer the question of what Islam is, Ahmed suggests, one must at least come to terms with what Islam was in the Balkans-to-Bengal complex, “as a matter of human fact.”

Among that region’s notable characteristics are the significance of rationalist philosophy (both in its purest form and as an epistemological framework for scholastic theology); the omnipresence of Sufi thought and practice; and the tradition of figural representation in painting. The writings of Avicenna, the 11th-century Persian polymath, and the great legacy of commentary he inspired advanced the idea of a superior Truth accessible to the most powerful intellects (belonging, naturally, to philosophers), and “a lesser version of that Truth that communicates itself via Prophets, such as Muhammad.” A prophet was, to Avicenna, a kind of “über-philosopher,” and the prescribed laws promulgated in the Koran were meant “to address the multitude in terms intelligible to them, seeking to bring home to them what transcends their intelligence by means of simile and symbol.”

This understanding of the relationship between reason and revelation prompted some charges of heresy, but the scale of Avicenna’s reception suggests that, in many quarters, he had won the argument, with his philosophical method and conceptual vocabulary becoming part of a standard scholastic curriculum across the Islamic world. In this light, if a modern definition of Islam does not account for the worldview of a figure such as Avicenna—whom Ahmed describes as “the man who effectively defined God for Muslims”—then something is amiss.

Ahmed examines the definition of Islam in a series of similar provocations. Alongside Avicenna, Hafiz, and the great Sufi thinker Ibn Arabi, he also considers the practice of wine drinking, a classical example of something prohibited by Islamic law and yet “positively valued in non-legal discourse.” The most cursory familiarity with premodern Islamic literatures, even beyond the Balkans-to-Bengal complex, attests to it. Poetry and belletristic prose in Persian, Arabic, Turkish, and Urdu fairly overflow with wine, while historical accounts of famous rulers and their courts portray scenes of literary salons congregating late into the night, fueled by musical performances and great quantities of drink. On the cover of What Is Islam? is one such sovereign, the 17th-century Mughal emperor Jahangir, pictured on the face of a gold coin contemplating a goblet of wine.

How to make sense of these contradictions? Since the beginnings of their academic study of the faith, scholars have grappled with the problem of reconciling the heterogeneity of Muslim beliefs and customs with the uniformity of “Islam.” One long-standing approach makes a distinction between the domains of “religion” and “culture.” Perhaps the most prominent representative of this school, the historian Marshall Hodgson, coined the term “Islamicate” to account for the fullest range of ways of thinking and living found within the cultural sphere of “Islamdom.” Ahmed thinks that Hodgson was motivated by the correct impulse, but came to the wrong conclusions. To separate religion from culture is to make an artificial distinction that becomes untenable in the case of Islam, in which religion and culture are thoroughly interwoven.

Another approach argues that it is senseless to speak of Islam as a monolith; what exists is an array of local islams. If Islam is anything, it is “whatever Muslims say it is.” This has a powerful and pluralistic ring; it accommodates both Avicenna and his great critic, Abu Hamid al-Ghazali, the 11th-century theologian. But as Ahmed observes, the islams argument is analytically weak, sacrificing explanatory power in the service of rhetorical efficiency. The assertion that Islam is whatever Muslims say it is offers a description, not a concept.

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The solution that Ahmed puts forward is a definition of Islam as an act of interpretation, something no less elemental than the production of meaning. It is not as narrow a practice as interpreting the Koran—the Text of Revelation—but is rather an engagement with the larger reality within which the Koran was revealed, what Ahmed calls the “Pre-Text of Revelation.” The Koran does not contain all truth; about this fact, there can be no disagreement. Where disagreement does exist “is over the question of whether and in what degree and by what mechanism the Truth of the Pre-Text of Revelation may be accessed.” Can one apprehend truth through some other means, such as the rationality of the philosophers or the Sufi “experiential annexation” of the self? Can the truth of the Pre-Text—which is ontologically prior to that of the Text—be accessed “without the Text, or via the Text, or only in the Text?”

For Ahmed, the history of Islam is a history of the many ways that Muslims have answered this question. It comprehends the literalism of “textual-restrictivists,” who give absolute priority to the text of the Koran and the Hadith (the corpus of sayings attributed to Muhammad) in determining a set of norms as exclusively Islamic, while rejecting other forms of interpretation. This history, of course, also embraces the authority of such “expansivist” projects as Islamic philosophy and Sufism, and everything in between.

When viewed as a single body, these different manners of interpretation form what Ahmed calls the “Con-Text of Revelation… the entire accumulated lexicon of means and meanings of Islam that has been historically generated and recorded up to any given moment: it is the full historical vocabulary of Islam at any given moment.” Something may be said to be Islamic—whether it is a law, a painting, an item of clothing, a poem, a joke—insofar as it expresses its meaning in the terms of Con-Text, connecting in some fashion with the whole archive of earlier hermeneutic engagements.

Can the celebration of wine drinking be Islamic? To Ahmed, the answer is: obviously, yes. It is Islamic insofar as this celebration is expressed, for example, in the terms of such classical Sufi metaphors for “the experience of intoxication with the Divine,” as well as the more mundane recognition of wine’s virtues as a social lubricant. The extensive medical literature of the premodern Islamic world attests openly to the latter fact. As the 10th-century physician and philosopher Abu Zayd al-Balkhi put it, “It is wine that provides excellence to society and conversation…and there is nothing that makes possible relations of intimacy and confidence between friends so tastefully and pleasantly and effectively as does drinking wine together.”

To say that wine drinking is un-Islamic may be akin to saying that the refusal to serve in the military during a period of wartime conscription is un-American. In the view of some citizens, such a refusal may well violate the essence of Americanness, in addition to violating American law; to others, however, this act may rather fulfill and epitomize the requirements of citizenship. By Ahmed’s logic, the refusal to serve in the military is not just American in spite of its opposition to other, contradictory values associated with Americanness, but precisely because of it.

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What is the use of a concept? Does it make any difference whether we conceive of Islam as a religion, a culture, a family of heterogeneous local islams, or a process of meaning-­making? Why and to whom do such distinctions matter? In the academy, concepts count for something, and Ahmed’s book represents the most sustained effort in decades to establish a conceptual basis for Islam. It goes without saying that his vision of Islam is a scholar’s vision; it is scholarly not merely in its style and rhetoric, but in the substance of its argument. If Islam is nothing less than the encyclopedic range of what it has been in history, it is impossible to be alive to that range of possibility without the deliberate study of its previous incarnations. No one could have felt this more deeply than Ahmed, whose shelves of orange file folders contained a millennium’s worth of thought and argument about a single event in Islamic history. While few could share his penchant for comprehensiveness, he believed that every Muslim had his or her own wall of orange file folders, so to speak, with which to make sense of the world.

It often seemed to me that Ahmed had contempt for the academy, even though he was as pure a product of it as could be imagined. He regarded the dominant approaches to conceptualizing Islam as structurally flawed, an assessment he documents at length in his book. Over a third of What Is Islam? is devoted to a tour of Orientalist, classical anthropological, and postcolonial scholarship on the subject. It is a survey that is, at times, hairsplitting, ungenerous, combative, and overwrought. It is also, as he put it resignedly to me before he died, “the bit that graduate students will probably end up quoting.” Unsurprisingly, the scholars whose positions are closest to Ahmed’s come in for the most sustained and sometimes withering evaluations, bringing to mind something that he liked to say about how it was “better to be 100 percent wrong than 50 percent right.”

Is Ahmed right? His definition of Islam as a model of “coherent contradiction”—one whereby a Muslim can simultaneously hold in mind many competing views of Islam’s teachings and values—is compelling; but is it true? There is something Gödelian in this project, an attempt to speak aloud a self-negating paradox. Perhaps an unavoidable consequence is that Ahmed’s arguments sometimes sound circular. If the Islamic is that which is recognizable in terms of what has been previously identified as Islamic, where does the buck stop? And might one not argue that any concept as vast as Islam must also be vastly self-contradictory and yet somehow coherent, especially when surveyed through the encyclopedic prism that Ahmed sets before his subject? What distinguishes Islam from such concepts as Christianity, Judaism, or liberalism in this respect?

A more significant problem concerns the consequences of insisting, as Ahmed does, on the inapplicability of distinctions like “religious vs. cultural” or “sacred vs. secular” when studying Islam. There is something unpleasantly exoticizing about making “Islamic” the only, or even the principal, lens through which to interpret a Hafizian love poem, a historic building, a metaphor, or a wine goblet. This was the sort of thing that got Orientalists into hot water: the assumption that every aspect of quotidian life in the societies of the Orient was somehow a reflection of Islam. The Orientalists, at least, pointed out the practices and artifacts that seemed to contradict the tenets of conservative piety. Ahmed’s “Islam” comprehends these contradictions, and so flirts with another analytical pitfall: the danger that “Islam,” by containing multitudes, means nothing in particular as a concept.

The academy is not the only place where concepts matter. Ahmed’s intended audience, one senses, also lies beyond the gates of Western universities. Looming in the background of the work is the specter of modern Muslim “textual-restrictivism” and “legal-supremacism,” as exemplified by many political Islamists. Here, he detects an ironic agreement between much Western scholarship and modern Islamist thought. Both groups concur that what is central to Islam is the law, which must be accessed through the study of the Koran and the Hadith. Philosophy and Sufism are dismissed by most Islamists as marginal—if not inimical—to the core of Islam, and to Ahmed’s great frustration, Western academics have tended to agree. Like the Islamist, the academic who makes a distinction between the religious essence of Islam on the one hand, and the cultural practices of the “Islamicate” on the other, is favoring one as more authentic than the other. To Ahmed, the modern fundamentalist happily agrees with this formula, insofar as it necessitates a return to “pure and authentic faith…back to the religion, back to Qur’an and [Hadith], back to the law, back to Islam, and not—God forbid!—to Islamicate.”

The challenge facing modern reformers is to circumvent this obstacle by making use of the rich resources of the historical tradition to explore the different modalities of Islam. Ahmed was quite pessimistic about this prospect, as he felt that the connection between Muslims and their medieval philosophical/Sufi heritage had become considerably attenuated in the modern world. Yet if a 14th-century theologian such as Ibn Taymiyyah—­the intellectual godfather of Wahhabism and other ultra-orthodox currents—­can become one of the best-selling authors of the contemporary Middle East, perhaps there is hope yet for Avicenna.

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Ever since he fell ill earlier this year, I have thought of my former teacher nearly every day. The fact of his death is difficult to accept, not merely because of his young age but because Ahmed inhabited, in my mind, a kind of future tense. Many of us—students, colleagues, and his own mentors—related to him in a mode of anticipation. To ask a friend for news of Shahab was to ask about the progress of his magnum opus, his life’s work. Is he finally nearing the end of the great book we’ve been waiting to read? Is he there yet? That there should suddenly be a book in the world with his name on it while the man himself is gone seems a cruel trick of fate.

Shahab Ahmed was buried on a beautiful fall morning in September. As a group of mourners prepared to lower his body into the earth, a quiet discussion arose among them about the lawful burial rituals. The group included Muslims from all over the world; naturally, the opinions varied. The matter was eventually settled, but I imagine that Shahab would have delighted in the knowledge that contradiction and debate accompanied him to the grave.