It is often the case that when questions have failed to be answered for a long time, as is the case with many of the questions on war, it is because the questions themselves have been posed in an unelucidating way. Much of the analysis in the previous chapters has been devoted to trying to pose questions about war in a manner that will make satisfactory answers more likely.

How should we ask questions about the causes of war? First, not all wars are alike, so this analysis seeks to explain one category of wars – wars of rivalry. Within that category, the focus is on wars of rivalry among the strongest states in the system, since more research exists on these states and their wars than on others. Second, not all wars are equal in their social or theoretical significance, so this analysis will place special emphasis on explaining the onset of world war. To do so means explaining why wars become total and complex; i.e., how and why most, if not all, of the major states are drawn into a war and why it is a war fought to the finish. Third, not all wars have the same causes, so while this analysis seeks to identify some of the sufficient conditions of wars of rivalry, it will not identify every causal sequence leading to war. And of the possible sufficient conditions, this analysis will focus primarily on identifying the foreign policy practices in the modern global system that appear to be associated with the onset of wars of rivalry.