Title | The Diffusion of Ideas

Abstract | New ideas can bring about social, institutional and technological change, if they diffuse successfully. How do increased connections affect the generation and diffusion of ideas? Intuitively, a denser network should increase the number of novel ideas generated and augment their diffusion. I show that in the context of knowledge production in Germany in the 19th century, the railroad network increases the generation of ideas, but decreases their diffusion. This is a by-product of specialization: with the railroad, groups of scholars can focus on narrower topics, they learn more from similar groups, but become disconnected from dissimilar ones. Specialization also affects state institutions: public officials and legislators are trained with a narrower but deeper focus of expertise. The bureaucracy thus becomes more specialized, and legislation is more exhaustive. The patterns generated by spatial connections are those that define modernity and the knowledge economy: specialization, the co-location of experts, the explosion of innovation. The findings rely on the universe of bibliographic records and novel railway statistics,  among other original data, as well as cutting-edge machine learning and topology to measure ideas.

Bio | Catrina is an Academy Scholar at the Harvard Academy for International and Area Studies. She received her Ph.D. in Political Economy and Government from Harvard University. In the fall of 2025, Caterina will join Columbia University's Department of Political Science as an assistant professor. Her research explores the political economy of innovation, regional inequalities, and state building. She uses machine learning, network analysis, and natural language processing to study large-scale historical and contemporary datasets.

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