A prominent “rationalist” explanation for war concerns commitment problems created by the anticipation of rapid shifts in power (see also here and here). When a state expects that the mere passage of time will lead it to fare worse in a potential future war against its rival, the rival’s inability to credibly promise not to exploit its future power by demanding a revision of the status quo can lead tempt the first state to attack so as to forestall (or at least slow down) the shift in power.
The canonical example of this was provided by Thucydides, who wrote in History of the Peloponnesian War “It was the rise of Athens and the fear that it inspired in Sparta that made war inevitable.” But today’s international relations students, alas, have little interest in antiquity. Nor are they particularly impressed by systematic evidence that wars occurred more frequently between 1816 and 2001 in the presence of observable indicators that a substantial shift in the bilateral distribution of capabilities was on the horizon (which I nonetheless provide in class). For better or worse, our students view as immediately suspect any theoretical claim that cannot be illustrated with an example they’ve actually heard of.
For that reason, I now discuss the American Civil War after explaining the general logic of commitment problems induced by an anticipation of a future shift in power.