Having written a number of important articles describing the central role that investments in human capital played in the economic outcomes of the Jewish People, Maristella Botticini and Zvi Eckstein have now produced a book-length study that systematically repudiates a number of competing theories attempting to explain why Jews were driven from agriculture in antiquity into urban crafts and trade in the medieval period and beyond. Refuting long-standing clichés that the Jews were driven into urban pursuits by virtue of being excluded from landholding, or that Jews chose to invest in education for its portability since persecutions (or potential persecutions) provided a disincentive to invest in landholdings, Botticini and Eckstein instead explain the Jewish focus on investment in education as proactive rather than reactive. Following Max Weber in arguing that distinctive religious preferences can produce differential long-term economic outcomes, the authors suggest that an exogenous Jewish religious preference for literacy gave medieval Jews a comparative advantage in availing themselves of economic opportunities in the cities of the emerging Islamic commercial revolution. This approach also allows the authors to reject the old refrain that Jews’ desire to live in proximity to one another in order to fulfill their religious obligations (if not to find a high-quality bagel!) led Jews to choose to live concentrated together in urban areas.

Botticini and Eckstein ascribe the Jewish preference for literacy to what they describe as an “historical accident”: the destruction of the Second Temple in Jerusalem by the Roman army in 70 CE. In the wake of this destruction, Jewish leaders “replaced temple service and ritual sacrifices with the study of the Torah in the synagogue, the new focal institution of Judaism.” (p. 6) In their reading of the historical record, rabbinic establishment of literacy education as a legal norm substantially raised the cost of Jewish observance (here, the authors draw on the work of Laurence Iannaccone and others quantifying costs and utility derived from religious participation), which drove many Jews to choose conversion to a religion (such as Christianity or Samaritanism) rather than bear the costs either of educating their children or of living a socially ostracized life as an uneducated Jew. In an annex to the fourth chapter (pp. 89–94), the authors present the first of two models which parameterize religious selection, highlighting the role of costs and utilities in marketplace of religion. In their view, massive conversions resulting from the high costs of literacy education are a key factor in explaining Jewish demographic decline in late antiquity (that is, roughly from the destruction of the temple until the rise of Islam) and trump other explanations such as deaths due to massacres and wars, a general population decline due to famine or disease, or a massive decrease in Jewish fertility in the period.

The great utility of Botticini and Eckstein's model becomes clear when the authors examine Jewish life in the first few centuries of Islam. In their account, massive urbanizations which took place in this period opened up new opportunities for Jews (who were, by the authors’ account, already literate) to reap the benefits of their investment in education; in consequence, nearly all of the Jews of Mesopotamia (itself fully 80 percent of world Jewry) left the agricultural hinterlands for the new Islamic cities. The urbanizing of the literate Jewish population poses a different challenge to the Jews, which allows the authors to revisit and to amend their model (on pp. 150–52): differential taxation of Jewish and non-Jewish merchants. The results of their amended model suggest that once the shift was made to the Islamic cities, only an extreme tax differential that outstripped merchants’ attachment to Judaism would lead Jews to convert. In their view, this, too, matches the historical record—suggesting that Jews did not convert in large numbers once they reached the cities.

At this point, Botticini and Eckstein shift from Jewish investment in literacy education to discuss what they see as other instruments for Jewish comparative advantage in trade and moneylending: universal contract-enforcement institutions provided by Jewish law, and social and economic networks with other Jews that stretched across large swaths of medieval Europe. The authors argue that these two characteristics of medieval Jewish life made the profitable field of moneylending an attractive choice even in the absence of occupational restrictions placed on Jews—which, they point out, postdate Jews’ involvement in moneylending in any case. Thus, medieval persecutions of Jews may have been the result of Jewish prominence in moneylending, but they were certainly not their cause.

The historical arc the authors draw comes to a close with their discussion of the thirteenth-century Mongol conquests, which (in their view) so ravaged urban areas in the heartlands of the Middle East. Botticini and Eckstein turn to their model to explain that in the wake of this devastation, waning opportunities to participate in urban crafts and trade led much of the Jewish population to convert to Islam. In their words, “Judaism thrives in urban and commercial societies and is bound to disappear when trade and urban economies collapse.” (p. 259)

While the authors make an important contribution in encouraging historians and economists alike to think about the costs and utility of participating in a particular religious group, with conversion as an option which can be no less quantified, Botticini and Eckstein vindicate their model by making assumptions about the historical record which are by no means warranted. Their assumption that classical rabbinic texts can be read as accurate depictions of historical reality leads them to the conclusion that literacy and contract enforcement were universal Jewish institutions. The evidence for either of these is thin at best—and, indeed, the work of Catherine Heszer in antiquity and Avner Greif in the medieval period suggests that these were anything but what Botticini and Eckstein imagine! Similarly, although it is worth thinking about when considering Botticini and Eckstein's parameterized model, it is unclear that there was ever an actual social cost associated with being an uneducated Jew. However, even if the authors are correct that medieval Jews were literate, it is unclear how literacy provides a comparative advantage for the majority of urban occupations (this would probably apply to tradesmen even in the modern period). Their reading of both the primary sources and the secondary literature on Jewish demography is also tendentious, rejecting more recent advances in scholarship and rereading medieval travelogues in the service of their historical narrative.

None of these criticisms should be seen as detracting from the book, which encourages serious consideration of the competition between religious groups (something already noted by scholars when considering religious law) and poses clear challenges to a number of clichés concerning medieval Jewish economic and demographic history.