I am told that the economics commentator Noah Smith linked to a 2016 paper of mine on Twitter today. I am not on Twitter and likely will never be on Twitter, so I can't link to this thread. Yet the paper is quite relevant for the current situation between Russia and Ukraine, so I can't resist commenting on it here.
In "War and Relatedness", Enrico Spolaore and I argued that societies that are more closely related in terms of culture, religion, ancestry, and language, are more likely to go to war with each other. This contrasts with a view that interstate wars feature a "clash of civilizations", a hypothesis articulated by political scientist Samuel Huntington in a 1996 book. This view implies that societies that differ in terms of religion, language, values, and common ancestry are more likely to fight. It is starkly at odds with the empirical evidence, which strongly supports the opposite view. Using a dataset of interstate conflict between 1816 and 2001, Enrico and I showed that a simple measure of relatedness between countries strongly predicts the likelihood of interstate conflict. This is a very robust relationship, which holds across the world, within Europe, and across the world after excluding Europe. It holds in different periods, and after controlling for an exhaustive list of geographic proximity measures. This is not about geography, but about human relatedness.
Why might there be a greater propensity to fight with culturally closer societies? Enrico and I articulated two mechanisms. First, closely related societies are likely to care about more similar resources. Many wars are over the control of good land or of natural resources such as oil. More similar societies are more likely to have preferences for the same rival goods, and to develop conflicts over goods or issues they both care about. Second, interstate wars are often about territorial disputes. When a country wishes to conquer territory from another, it cares about its ability to manage the new territory in the event of victory. It is easier to administer and integrate a more similar population after conquest, than a very different one.
The example of Russia and Ukraine (very closely related societies in terms of ancestry and culture) provides a very nice example of our theory. Moreover, Russia seems mostly interested in regions of Ukraine (Crimea, Donbas) where a strong presence of ethnic Russians will make post-conquest administration easier. In fact, in our 2016 paper, Enrico and I explicitly mentioned the case of Crimea:
"For instance, the recent conflict between Russia and Ukraine over Crimea and the Eastern region of Ukraine (not included in our sample, which stops in 2008) is consistent with our prediction that states with closely related populations are more likely to engage in conflict over control of rival goods and populations." (p. 937)
The thesis of this paper has held up quite well in light of recent events - if I may say so myself!