To understand why citizen participation in politics succeeds and fails, this book has focused on participatory budgeting, probably the most well-known democratic innovation worldwide. I have traced the development of comparative work on PB as the innovation has diffused and as knowledge of the field has developed. I was motivated to figure out under what circumstances citizens involved in programmes designed to engage them in governance gain meaningful control of important collective decisions. I have shown that as the field of democratic innovation, and in particular, PB, matures, significant steps have been taken in the direction of a more systematic comparison providing ever better answers to that question.

Parts II and III presented and discussed practical issues involved in undertaking advanced QCA across cases. I argued that we can better understand participatory democracy by allowing an assessment of the value and potential of cumulating existing knowledge using systematic formal logic. My aim was never to undercut other approaches or extol the virtues of one approach, but rather to provide a new complementary approach. Up to now research has focused on in-depth qualitative small-N research, or large-N studies that either focus on individuals as the unit of analysis or on breadth at the expense of depth. The value of robust and general findings is that they can allow relevant actors – civil society activists, political leaders and even academics – to plan their actions with a degree of confidence in the lessons of evidence. My work offers notable improvements in our understanding of participatory democracy, and I identify complementary tools of analysis that should be of use to those interested in furthering their knowledge of PB. The QCA approach to cumulating and systematically reviewing the evidence of previous research reveals redundant elements of causal claims or identifies oversimplification. I conclude here by outlining the key findings and their implications for the theory and practice of democracy.

Looking back before looking forward

In introducing the book, I outlined a set of key wider debates that the work presented here will contribute to. I certainly did not need to demonstrate that highly democratic outcomes are achievable in PB programmes – that has been done before – but I have shown that these democratic improvements are relatively widely spread, varying in both their number and qualities.