Pairs of states, which are more similar to each other in their regime characteristics, have been found to be interconnected through diplomatic ties, international organizations, and other international relations more frequently. According to one possible explanation for this observation, diffusion of democratic norms and liberal institutional arrangements through international networks fosters democratization in individual states. If this argument holds, nondemocratic or less liberal states which are well connected to democracies or more liberal states should be more prone to liberalization. A different explanation postulates a causal relationship in the opposite direction: States with similar regime characteristics are theorized to be more likely to connect with each other over time and establish bilateral diplomatic relations, for example. Only if the first of these two explanations is supported by empirical evidence, the importance of diffusion in democratization studies is strengthened.
This paper adopts a social network perspective, which has only recently been introduced into Comparative Politics and International Relations. A stochastic actor-oriented model for the simulation of network evolution (SIENA) is applied for testing these competing explanations. Using the influence-versus-selection framework, this quantitative modeling approach is particularly suitable for longitudinal network data and the research question at hand.
