[rocqua]

> For one thing, the IR significantly predated WW1 and WW2. It didn't prevent those, so how'd it cause the "long peace" afterwards?

The Wikipedia article about both the long peace and hegemonic stability theory. Both mention 3 nain examples. The pax Romanica (Roman times), the pax Britannica (1820-1914) and the Pax Americana (1945-now).

The Pax Britannica happened after the industrial revolution was wide-spread. Only the Pax Romana was before the industrial revolution, and it was far from global.

I would suggest that perhaps the long peace is actually from 1820 till now. With both world wars serving as examples where the calculus against war was ignored, and then later proven correct. Which fits with the theory, which says 'industrial war isn't worth it'. If once in a while a big power decides to test that theory, or decides war is necessary for non-economic reasons, you get horrible wars.

Not to say that hegemonic stability theory is clearly wrong. Just to say that the 'industrial revolution means war isn't worth it theory' fits the Pax Britannica and Pax Americana quite well.