Measuring common knowledge: Latent semantic analysis, linguistic synchrony, and common knowledge in international relations

Common knowledge, also called intersubjectivity, is a core theme in the study of international cooperation and diplomacy. Yet International Relations (IR) lacks a method to systematically measure the degree of common knowledge. Drawing from research in computational linguistics, psychology, and communication, we introduce latent semantic analysis (LSA) to measure common knowledge in specific communicative exchanges between actors. We argue that the extent to which speaking partners use words in the same way and get in synch linguistically can be used to measure the degree of common knowledge, and this can be measured by the LSA method. We outline several ways LSA can be valuable to IR scholars and provide an empirical illustration of using this method in the case of Bretton Woods negotiations. The LSA method promises to help IR scholars seize the research opportunities offered by the digital age and build a bridge between qualitative and quantitative methods.