What is new in the Study of Policy Diffusion

Abstract

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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 innovations in this literature. On the theoretical side we argue that, whereas it is acknowledged that the various diffusion mechanisms overlap, hardly any attention is devoted to the way in which they interact (either with other mechanisms of diffusion or with domestic factors). More generally, mechanisms are studied separately and are not integrated into a coherent model of diffusion. On empirics, we argue that existing studies have concentrated on policies that seem to have diffused in an explosive way even though both theory and methods are appropriate to study any type of diffusion. More attention should also be paid to modeling diffusion processes to account for the fact that causal patterns may be highly heterogeneous in time and space. We show that the latest wave of studies on diffusion may have had the unintended consequence of opening up new questions. Some of these questions are about the mechanisms that initiate rather than accelerate the diffusion of policies and institutions, why policies diffuse in clusters rather than globally, why some policies diffuse faster than others and why some policies do not diffuse at all. Finally, we present and discuss the contributions in this issue, which tackle many of the points posed above.