Did the language of medieval inquisition records become richer over time? A diachronic lexical richness perspective on heresy trial proceedings from Languedoc and Italy, 1231–1400

While medieval inquisition records have a reputation for containing standardized and formulaic administrative language, some display a thematic richness and discursive variety that extends beyond the norm, especially in records of depositions. There is also a notion that registers were becoming richer over time, moving beyond the modest beginnings of inquisition documentation in the 1230s–40s as investigative interests expanded. However, thus far there has been no formal and systematic analysis of the language of these records that would address these questions. To study the elaboration of language and assess its growth over time, we apply nine lexical richness metrics to a representative sample of over twenty inquisition registers (with 2.28 million word tokens) from Italy and Languedoc, compiled between 1231 and the end of the fourteenth century. Regression analysis indicates a significant growth in lexical richness over time in all nine metrics. We also perform a comparative analysis of the registers, report on various aspects of the behaviour of vocabulary, and offer a historical interpretation.