Writers of many philosophical persuasions have proposed numerous other causes (some might say excuses) for war. Conservatives, liberals, and radicals differ in their explanations (Chapter 5).
To demonstrate their number and variety, thirty-two suggested causes1 of war are:| Race† | Power (balance, preponderance, transition)* |
| Pride* | Lack of peaceful means to resolve disputes* |
| Cycles* | Distract citizens from domestic discontents* |
| Polarity* | Number of bordering states* |
| Ideology† | Military-industrial complex* |
| Insanity* | Protection of human rights* |
| Religion† | Characteristics of states* |
| Jealousy* | Ecological equilibrium* |
| Arms races* | Form of government* |
| Nation-states* | Trade or trade routes† |
| Expected utility* | Personality of leader† |
| Astral influence* | Territorial imperative* |
| War profiteering* | Reproductive success* † |
| Manifest destiny† | Take or hold power† |
| Balance of power* | Relative deprivation* |
| Resource shortages* | Season of the year* |
Some of these may be necessary, some sufficient, some necessary and sufficient, some contributory causes of war (Chapter 1). Some may be false. Religion as a cause of war is said to have ended with the Thirty Years War—but it may be coming back with the rise of Islamic terrorism. Season (spring when the roads were passable or fall when the harvests came in) may once have been relevant as to when wars started rather than as a cause of war, but is less so now. It may be possible to find a war or two started only because of insanity, jealousy, or pride, but they are too rare to warrant systematic study.