Reflections on the policy diffusion debate

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 any attention to the way in which they interact (either with other mechanisms of diffusion or with domestic factors). More generally, mechanisms are studied seperately and are not integrated into a concentrated on policies that seem to have diffused in an explosive way despite the fact that both theory and methods are appropriate to study any type of diffusion. We argue that new emperical work should tackle the difficult issue of how to better operationalize alternative diffusion mechanisms. More attention should also be given to modeling diffusion processes to account for the fact that causal patterns may be highly heterogeneous in time and space. Finally, we show that the last wave of studies on diffusion may have has the unintended consequence of opening up new questions. Some of these questions are about the mechanisms that initiate vs. accelerate the diffusion of policies diffuse faster than others, and why some policies do not diffuse at all.