The essays in this extremely useful volume, many of them previously published in International Security, bring together much of the work done on the "democratic peace" hypothesis in recent years. The assertion that democracies tend not to fight one another is, in Bruce Russett's words, "one of the strongest nontrivial and non-tautological generalizations that can be made about international relations," and the academic debate on the issue has been both interesting and of high quality. The volume begins with such proponents of the hypothesis as Russett and Michael Doyle, then moves to counterpoints by Christopher Layne, David Spiro, and Jack Snyder. The controversies they address concern how to define democracy, empirical evidence of wars or near wars, and the causal connections between democracy and peace.
It is hard not to conclude that an important relationship binds democracy and peace, though it has certain qualifications: it is not an iron rule, but a correlation that is dependent on the degree to which not just democratic but liberal institutions and norms are consolidated. Hence it is not surprising that many of the counterexamples cited by critics concern borderline liberal-democratic states such as the American South, Wilhelmine Germany, or the Soviet successor states. The policy question then is not whether democracy is conducive to peace, but under what circumstances it is reasonable to expect democracy to develop, and what instruments outside states have for promoting it. This question, falling as it does more within the province of comparative government and political economy than international relations, is the one missing piece of an otherwise excellent volume.