What factors caused the persecution of Jews in medieval and early modern Europe? A new analysis of a data set of 700 years of European Jewish persecutions and expulsions argues that a decrease in temperature which affected a city's crops and resources led to an increase in the likelihood that that city would expel its Jews. Forming the basis for a thought-provoking paper titled "From the Persecuting to the Protective State? Jewish Expulsions and Weather Shocks from 1100 to 1800," a new study explores whether there is a relationship between weather and growing season and the likelihood that the Jewish community would be expelled, and finds that there is. It found that "negative supply shocks" brought on by inclement weather often constituted a trigger that led to expropriations and expulsions in societies that were permeated with anti-Semitism, especially in the areas that now constitute Poland and Germany. "A one standard deviation decrease in temperature is associated with approximately a 1% to 2% increase in the probability of expulsion during any given five-year period. The effect of supply shocks on expulsions is larger in areas with poor soil quality for wheat cultivation and more muted in areas with good quality soil," the researchers concluded. The three researchers Warren Anderson from the University of Michigan-Dearborn, together with Noel D. Johnson and Mark Koyama from George Mason University published their remarkable findings in February in the Social Science Research Network, a resource for sharing and disseminating scholarly research worldwide. Viewed through this lens, the results suggest that temperature shocks put pressure on rulers to expel Jews both as a means to expropriate their property and thereby make up lost tax revenue as well as to quell popular violence. Using data on Jewish populations, expulsions and other episodes of organized violence from the 26-volume Encyclopedia Judaica (2007), the researchers built a model that predicts that minority communities were more likely to be expropriated in the wake of negative income shocks. They used panel data consisting of 785 city-level expulsions of Jews from 933 European cities between 1100 and 1800 to test the implications of the model. The researchers used the variation in city-level temperature to test whether expulsions were associated with colder growing seasons. "We find that a one standard deviation decrease in average growing season temperature in the fifteenth and sixteenth centuries was associated with a one to two percentage point increase in the likelihood that a Jewish community would be expelled. Drawing on our model and on additional historical evidence we argue that the rise of state capacity was one reason why this relationship between negative income shocks and expulsions weakened after 1600." Using data on climatic variation, they identified the effect that negative economic shocks had on minority rights in the preindustrial period and show that the relationship between climatic shocks and the expulsion or persecution of Jewish communities was strongest in the fifteenth and sixteenth centuries and disappeared after 1600, when there was no longer a discernible effect of weather on expulsions. The researchers present evidence that indicates that the rise of more powerful states was an important factor in explaining why weather shocks ceased to be associated with expulsions after 1600. "Medieval states were weak. They were vulnerable to economic shocks and popular unrest, and though they depended on minority groups like the Jews for financial expertise and as a source of revenue, they were willing to sacrifice the rights of those very same minority groups in order to sate popular anger and to meet pressing financial exigencies," the paper states. "The early modern nation states that emerged after 1600, in contrast, succeeded in building fiscal and legal capacity; they were no longer dependent on taxing economically prosperous minorities, and more importantly still, they enjoyed greater political stability and ceased to be responsive to popular unrest and anti-Semitism." The team focused on the persecution of the Jews in medieval and early modern Europe, one of the most numerous and best documented minorities throughout European history. "Violence against Jews was caused by many factors, but we build on the common claim advanced by historians that Jews were convenient scapegoats for social and economic ills," the researchers said. Jews in medieval Europe comprised a market dominant minority. While Jewish communities have existed in southern Europe since Roman times, permanent Jewish communities only appeared in northern Europe in the ninth and tenth centuries. They came for economic purposes as traders and as merchants. Rulers encouraged Jewish settlement in order to encourage commerce, investment, and economic development. By 1100 there were a large number of Jewish settlements scattered across England, France and Germany in addition to the large Jewish population in Spain. The team's conclusions: Negative economic shocks led to popular unrest and this unrest resulted in the scapegoating of minority groups, i.e., persecution from below. Negative economic shocks also put greater pressure on royal finances and led rulers to expropriate and expel the minority groups, i.e., persecution from above. Both of these channels suggest that the effect of negative weather shocks on expulsions should have been greatest in regions with poor quality soil and, therefore, a greater underlying vulnerability to agricultural shocks. "It is important not to overstate the frequency with which Jewish communities were threatened with violence and pogroms many Jewish communities lived in peace with their Christian neighbors for long periods of time. But as an economically dominant minority in poor and largely agrarian economies, and as outsiders in a society that increasingly aggressively defined itself in opposition to infidels and unbelievers, Jews often aroused jealousy and suspicion from others." Using their model, the researchers corroborated other studies which found that cold weather shocks were associated with witchcraft trials in Africa, and that high levels of precipitation were associated with a higher number of witchcraft deaths in Tanzania, and that lower temperatures were associated with more severe sentences being passed down by the Portuguese Inquisition.
