Earthquakes, Religion, and Transition to Self-Government in ItalianCities

This article presents a unique historical experiment to explore the dynamics ofinstitutional change in the Middle Ages. We have assembled a novel data set,where information on political institutions for northern central Italian citiesbetween 1000 and 1300 is matched with detailed information on the earthquakesthat occurred in the area and period of interest. Exploiting the panel structureof the data, we document that the occurrence of an earthquake retardedinstitutional transition from autocratic regimes to self-government (thecommune) in cities where the political and the religious leaders were the sameperson (episcopal see cities), but not in cities where political and religiouspowers were distinct (non–episcopal see cities). Such differential effect holdsfor destructive seismic episodes and for events that were felt by the populationbut did not cause any material damage to persons or objects. Ancillary resultsshow that seismic events provoked a positive and statistically significantdifferential effect on the construction and further ornamentation of religiousbuildings between episcopal and non–episcopal see cities. Our findings areconsistent with the idea that earthquakes, interpreted in the Middle Ages asmanifestation of the will and outrage of God, represented a shock to people’sreligious beliefs and, as a consequence, enhanced the ability ofpolitical-religious leaders to restore social order after a crisis relative tothe emerging communal institutions. This interpretation is supported byhistorical evidence.