Renate Mayntz and I have selected the label "actor-centered institutionalism" for the framework that has oriented our research since the beginning of the 1970s and that we first explicated in a volume that presented an overview of the work of our institute ( Mayntz/ Scharpf 1995b). The material contained in this chapter and the next therefore represents her thinking as much as it does mine. But we are not alone in recognizing the need to combine actor-centered and institutioncentered approaches in an integrated framework. Others have chosen different labels to describe the same fundamental idea. Elinor Ostrom and collaborators ( Ostrom/ Gardner/ Walker 1994), for instance, use an "institutional analysis and development" ( IAD) framework to analyze the resolution of common-pool resource problems; Tom Burns and collaborators ( Burns/ Baumgartner/ Deville 1985) speak of "actor-system dynamics" (ASD); and Michael Zürn ( 1992) prefers to call his framework "situation-structural." What these approaches have in common is an integration of action-theoretic or rational-choice and institutionalist or structuralist paradigms, which, in the confrontation between "economic" and "sociological" theories, are conventionally treated as being mutually exclusive. 1 What is gained by this fusion of paradigms is a better "goodness of fit" between theoretical perspectives and the observed reality of political interaction that is driven by the interactive strategies of purposive actors operating within institutional settings that, at the same time, enable and constrain these strategies. What is lost is the greater parsimony of theories that will ignore either one or the other source of empirical variation.
But as I pointed out in the previous chapter, this is a parsimony that we cannot afford in empirical policy research. Policy, by definition, is intentional action by actors who are most interested in achieving specific outcomes. Thus, unlike in some types of sociological theory, we cannot assume that they will merely follow cultural norms or institutional rules. We also cannot assume, however, as is done in neoclassical economics or in the neorealist theory of international relations, that the goals pursued or the interests defended are invariant across actors and across time. Rather, we know that actors respond differently to external threats,