🔎 What was studied

This study examines how expulsions of Jews spread across more than 500 polities in the western Holy Roman Empire between 1385 and 1520 CE. Although medieval governors often had both religious and material reasons to avoid expulsions, expulsions rose sharply in the fifteenth century. The key question: did one city’s decision to expel influence neighboring or connected cities?

🧭 How diffusion theories were tested

• Three common diffusion mechanisms were evaluated: learning (copying policies because they worked), social reinterpretation (changes in theology or discourse that reframe a policy’s value), and social-structural/resource constraints (political and economic incentives shaped by inter-city power and dependency).
• Statistical models were applied to a dataset covering over 500 polities in the western Holy Roman Empire from 1385–1520 CE to assess which mechanisms best explain the pattern of expulsions.

📊 Key findings

• No evidence was found for learning: cities did not adopt expulsions simply because others’ expulsions appeared effective.
• Evidence supports social reinterpretation: theological shifts gave expulsions renewed political utility.
• Evidence also supports social-structural/resource constraints: adoption tracked political and economic incentives embedded in inter-city relationships of power and dependency.
• Spatial proximity and social influence did not uniformly accelerate ethnoracial extremism; diffusion depended on the structure of political and economic ties rather than mere closeness.

💡 Why this matters

• Demonstrates that policy diffusion of exclusionary measures can hinge less on imitation and more on changing ideational frames plus underlying political-economic structures.
• Suggests caution in assuming geographic proximity alone drives the spread of discriminatory policies; networked power relations and shifting discourses can be decisive.