A variety of factors have constrained progress on deciphering escalation to war. One is the sheer complexity of the undertaking. International relations are hardly simple and uncomplicated phenomena. Laws of interstate interaction are not readily established and, in any event, will probably prove to be the wrong goal to pursue in unraveling highly complex behavior. A second factor that derives from the complexity is that we tend to focus our explanatory efforts on favored, relatively monovariate, causal elements. One group pursues alliances, another dwells on arms races, and still others specialize in the analysis of rivalry or crises. There is much to be gained from concentrating on specialized topics. But there is also a price to be paid if we remain concentrated too long. Conflict escalation, without doubt, involves multiple causation.

To develop satisfactory explanations of processes subject to multiple stimuli, we need to introduce multiple explanatory factors simultaneously, and possibly interactively, as opposed to separately. However, a third factor that has held us back is that our explanatory apparatuses tend to be linked to the preference for monovariate explorations. We have tended to study individual hypotheses about alliances, or arms races, or crises. Do alliances tend to be followed by war? Are arms races genuinely influential in escalation processes or merely symptomatic of underlying tensions? What types of crises are most likely to lead to war? These are all relevant questions but we need to test more complex arguments that make linkages among alliances, arms races, and crises.