Reflections on the Policy Diffusion Debate

Abstract

This paper surveys what is new in the study of the international diffusion of policies.We critically review the most recent contributions on the topic, trying to identify the substantive and methodological novelties in this literature. Regarding mechanisms,we argue that whereas there is acknowledgement that they overlap, there is hardly anyattention to the way in which they interact (either with other mechanisms of diffusion orwith domestic factors). More generally, mechanisms are studied separately and are not integratedinto a coherent model of diffusion. Regarding empirics, we argue that existingstudies have concentrated on policies that seem to have diffused in an explosive waydespite the fact that both theory and methods are appropriate to study any type of diffusion.We argue that new empirical work should tackle the difficult issue of how to betteroperationalize alternative diffusion mechanisms. More attention should also be given tomodeling diffusion processes to account for the fact that causal patterns may be highlyheterogeneous in time and space. Finally, we show that the last wave of studies on diffusionmay have had the unintended consequence of opening up new questions. Some ofthese questions are about the mechanisms that initiate vs. accelerate the diffusion of policiesand institutions, why policies diffuse in clusters rather than globally, why some policiesdiffuse faster than others, and why some policies do not diffuse at all.