The democratic and oligarchic peace are also strengthened by the culture of arbitration and the respect for the ingroup opposition in both democracies and oligarchies. Similar policies are applied to foreign policy to deal with states belonging to the ingroup. In contrast, the leaders of autocracies are the survivors of a culture of violence against opponents. They use similar methods to deal with other states, which often cause wars. The book presents earlier statistical studies and case studies to show that democracies and oligarchies conduct diplomacy very differently from autocracies. Weart argues against explanations like more trade between democracies since he fjnds the pattern to change too abruptly for that to be the case.