Democracies rarely if ever fight one another, but they participate in wars as frequently as autocracies. They tend to win the wars in which they participate. Democracies frequently build large alliances in wartime, but not only with other democracies. From time to time democracies intervene...

According to the liberal peace proposition, pairs of democratic states and pairs of states with extensive trade ties are more peaceful than other pairs of states, and democratic states are also more peaceful internally than other regime types. This article reviews the recent literature on the...