Abstract
Censorship makes new ideas less available to others, but also reduces the share of people choosing a non-compliant activity. We propose a new method to measure the effect of censorship on knowledge growth, accounting for the endogenous selection of agents into compliant vs. non-compliant ideas. We apply our method to the Catholic Church's censorship of books written by members of Italian universities and academies over the period 1400-1750. We highlight two new facts: once censorship was introduced, censored authors were of better quality than the non-censored authors, but this gap shrunk over time, and the intensity of censorship decreased over time. These facts are used to identify the deep parameters of a novel endogenous growth model linking censorship to knowledge diffusion and occupational choice. We conclude that censorship reduced by 30% the average log publication per scholar in Italy. Interestingly, half of this drop stems from the induced reallocation of talents towards compliant activities, while the other half arises from the direct effect of censorship on book availability.