Did the plague kill half the Roman Empire? | Anthony Kaldellis and Lex Fridman

In this discussion, Kaldellis addresses the historical debate surrounding the Plague of Justinian and its demographic impact on the Roman Empire. He notes that recent laboratory science has confirmed the pathogen as Yersinia pestis, replacing previous guesswork. However, he emphasizes that identifying the pathogen does not automatically determine mortality rates or historical impact—this still requires traditional historical methodology.

Kaldellis expresses skepticism toward the maximalist position claiming 50% mortality, arguing this would have logistically halted society entirely. He instead advocates for a much more moderate impact assessment. His primary evidence comes from examining what actually happened during the plague period: Justinian continued waging war on four or five fronts simultaneously, with no narrative pause or disruption to military operations. Taxation and court functions continued uninterrupted, with no visible impact on governance or military conduct.

Kaldellis draws a comparative example from the Black Death in 14th-century Europe, where detailed records show societal breakdown lasting several years before recovery. Since this collapse is absent from 6th-century sources during the Justinian plague, he concludes the actual mortality and social disruption must have been significantly lower than the 50% claim. He positions this as an ongoing scholarly debate with multiple interpretive possibilities.