The history of Islamism in the twentieth century is one of lay preachers calling for a return to Islamic values, laws, and governance in the modern world. Paradoxically, formally trained Muslim clerics play a relatively minor role in this influential movement. Hassan Al-Banna, the founder of the Egyptian Muslim Brotherhood movement, began his career as a schoolteacher. Abul A’la Mawdudi, the founder of the Indo-Pakistani Jamaat-e-Islami movement, spent much of his early life as a journalist. Sayyid Qutb was a teacher and a literary critic before he became the author of Milestones, the manifesto of radical Islamism. With few notable exceptions, such as the case of Ayatollah Khomeini leading the 1979 Iranian revolution, Islamists by and large are engineers, mathematicians, physicists, doctors, pharmacists, lawyers, journalists, and businessmen. European Islamists, generally speaking, are usually converts to Islam or secularists-turned-Islamists under the influence of street preachers or radicalizing social media.

Richard A. Nielsen’s Deadly Clerics studies the exception to this general pattern. He draws our attention to a subset of jihadists who were formally trained clerics prior to turning into proponents of Islamist militancy. These include Abdullah Azzam, the original mentor of Osama Bin Laden; Abu Bakr al-Baghdadi, the self-proclaimed caliph of the Islamic State; and Anwar al-Awlaki, the first American citizen to be killed by the United States in a legally sanctioned targeted assassination. The author asks: Why do these clerics, and others like them, choose the path of jihadism?

The book offers an eloquent and parsimonious answer to this puzzle: “When would-be academics have their ambitions blocked, either by forces within the academic system or by intervention from the state, they are at greater risk of turning to jihadist ideology” (p. 14). In other words, rather than being inspired into radicalism by the content of their religious education, they are driven into extremism by the constraints imposed on their academic careers. The blocked-ambition theory puts the emphasis on the academic identities of clerics, not their religious preferences. Their religious radicalism develops after the state suppresses their prospects for a thriving career inside the halls of academe.

The converse is also true: Clerics who are employed by the state and recognized by their scholarly peers—that is, Abdel Aziz Bin Baz, Muhammad al-Albani, Abdel Aziz Al al-Sheikh, and Muhammad Ibn al-Uthaymeen—tend to develop as political quietists or even as critics of jihadists. The different pathways to quietism and radicalism are related to the difference between being insiders and outsiders of religious academia. Nielsen’s book, echoing Diego Gambetta and Stephen Hertog’s Engineers of Jihad (2016), introduces a “disgruntled-graduate-student theory of jihad” (p. 2).

Nielson highlights a number of psychological and sociological mechanisms that link blocked ambition to support for jihadism. These include disappointment leading to a desire to change one’s circumstances and hindsight bias leading to resentment against a “rigged system.” Jihadism as a political ideology can appeal to frustrated clerics because its core mission is to transform the extant order that blocks their ambition. Additionally, radical Islamists need clerical authorities with religious credentials and ideological independence to justify violence against the regimes they seek to topple. This creates an alternative market for the social capital that clerics possess through their education.

Drawing upon a representative sample of 200 clerical biographies online, Nielsen conducts a series of statistical tests to see if the markers of blocked ambition correlate with support for jihadism within his data. He also seeks to account for the alternative hypothesis that jihadists develop clerical credentials after embarking on a militant path. He does this by controlling for several confounding variables—attending religious primary schools (leading to early career networking opportunities), levels of religious expertise (less intelligent clerics are not selected in a tight labor market), and exposure to Western society (host-country alienation can radicalize clerics). He finds “that clerics’ educational networks and career trajectories are strongly associated with subsequent jihadist ideology, and that a number of plausible alternative arguments fail to find support” (p. 154). Put differently, while the book cannot make a case for causation beyond mere correlation, the blocked-ambition theory maintains its plausibility because alternative explanations lack empirical support. This modest claim does not make for the most compelling argument, but it is actually a refreshing admission that invites others to delve further into this topic.

Deadly Clerics is commendable because it tackles an original puzzle and attempts to answer it with rigor. More interestingly, it digs deeply into how Muslim clerics are produced and what they do, especially in the age of the Internet and social media. Muslims often joke about “Sheikh Google,” and Nielsen adroitly describes this postmodern melding of religious authority with transnational technologies. For example, Figure 2.1 (p. 44), on the most common topics discussed in 105,000 online fatwas, is fascinating because it simultaneously tells us what is on the minds of ordinary Muslims and demystifies Western notions that jihad is of primary concern for religious adherents of Islam.

The book, however, calls for some critical engagement. I take issue with Nielsen’s definition of Muslim clerics as “individuals who produce religious content for public consumption within an Islamic tradition” (p. 29). This definition is too broad, akin to defining a political scientist as any person who writes political op-eds. Given the richness and complexity of the inherited Islamic legal tradition, Muslim scholars would insist that a cleric deserving of the name must be an erudite individual with knowledge of classical Arabic and its rules of grammar, foundational rules for deriving Islamic law (qawa’id fiqhiyyah), traditional juristic interpretations of the Koran, the science of hadith (Prophetic traditions), the theory of abrogation (naskh wal-mansukh), and so on. These requirements are just a few of the prerequisites for qualification as a religious authority.

Just as importantly for the theory, developing deep knowledge of Islam and its jurisprudence is central to the argument that clerics are individuals with ambition demonstrated through a time-consuming educational process. By selecting the weakest definition possible, it is difficult to make the claim that those in the data who lack the pedigree of scholarly training can be said to be ambitious clerics.

Additionally, statistical controls aside, the author could have presented a more compelling narrative of the way that blocked ambition is the cause of radicalization, as opposed to the alternative explanation that radical ideas result in career-ending repression. The example of the Saudi cleric Nasr al-Fahd, which the author presents as illustrative of his theory (p. 12), actually illustrates the opposite. His insult toward a Saudi prince’s wife was a political act that only the most daring individual would venture in the highly conservative and repressive Saudi state. The act is evidence of a predilection toward political contestation leading to blocked ambition, not the other way around.

These criticisms do not detract from an otherwise informative and well-researched book. Deadly Clerics is easily readable and plenty engaging. I have no doubt that it will find a home on many undergraduate and graduate syllabi of courses dealing with political Islam, terrorism, and radicalization studies.