Chapter 15 provides a summary of the arguments and evidence presented in the book. It then considers the tricky question of determinism in the causal arguments put forward. It argues that the theory presented here is deterministic insofar as environments shape the space for agency and that opportunities to exercise democratic rights are not randomly distributed throughout the world. At the same time, it is recognized that the theory is imperfect in its explanatory power and that individuals retain free will and agency that create uncertainty and cut against determinism. It is openly admitted that the theory cannot explain all variation in democratic outcomes, but it is contended that it nonetheless advances our understanding. It is also openly admitted that in looking at the deep roots of democracy, the theory produces no obvious policy recommendations. It is hoped that the framework can help inform studies of more proximal causes of democracy that are more likely to produce actionable policy recommendations.