Again I'm cribbing from something I wrote for Yahoo!Answers.
The question was, "10 reasons why world war 2 started?"
My answer, composed rather off the cuff, ran as follows:
I'm glad you allow for causative pluralism. I'll get you half way there with five causes:
1. The inherent dynamism of fascistic nationalisms, which need to prove their superiority to other nations in order to secure their domestic support;
2. In Japan (which wasn't really fascistic in the same sense as its European allies) a collective inferiority complex, which left them wanting to prove themselves at least as powerful as the western imperialists operating in east Asia;
3. The widespread theories of Admiral Mahan on the centrality of naval power in history, and the superior position in which island-nations are placed for empire building. This, too, inspired Japan and helped guide other nations too in a disastrous direction;
4. The excesses of the Versailles Treaty that the victorious powers had forced upon Germany in 1919, and the bitterness caused by that excess;
5. The long reign of Hegelian philosophy in German intellectual life, and the central role that philosophy assigned to nation-states, and to warfare as the tribunal of disputes between them.
Going beyond what I wrote there....
I'm not sure whether this is consistent with the various things I've said here about causes-of-war. I put it here precisely so as to keep myself from brushing under the rug any inconsistency that may exist.
And that's Admiral Mahan in the photo at top. He taught that Britain had been dominant for so long largely because it is an island nation, so it doesn't need to divide its navy. France has always had to divide its navy, maintaining a separate Mediterranean and Atlantic fleet (and Britain has controlled Gibraltar). The idea probably helped inspired Theodore Roosevelt to push for a Canal that could unite the two coasts of the US and that would be within US control -- so we wouldn't be France. It certainly encouraged Japanese ideas that it was now their turn to create an Empire analogous to Britain's.
But the Japanese were also perceptive about how Mahan's ideas had become obsolete. For his focus on the need to concentrate the fleet to make decisive use of it (or to hold it as a very public deterrent) became dangerous as air power became a factor, and the Japanese demonstrated this against an over-concentrated US Pacific fleet in December 1941.