We began by questioning the widely held premise of econometric research that federalism is generally inimical to the growth of the welfare state in all countries and in all eras. Employing a qualitative comparative approach that Peter Hall calls ‘systematic process analysis’, we derived our hypotheses concerning federalism's effects on welfare state development from theories of fiscal federalism and political institutionalism. According to theories of actor-centred institutionalism, institutions create opportunity structures for political action by shaping actor constellations, actor preferences and the modes of their interaction. Exploiting these institutionally pre-configured opportunities for public policy-making, then, depends on a number of contextual variables. We have used middle-range theories of the determinants of welfare state development to predict the power of these contextual factors to impede or enhance our eight hypothesized effects (table 1.8).

We have also argued that the time dependence of institutional effects should be taken into account. The reasons were several. First, as shown in the path dependency literature, iterative political decision-making involves a sequential process in which earlier decisions strongly influence the trajectory of subsequent policy development. Second, the impact of federalism on social policy is contingent upon the stage of welfare state development, that is, whether social policy is in the process of initiation and expansion, or whether it is undergoing retrenchment.