This activity comes after students are to have listened to a lecture (slides) on information problems as an explanation for war—which I’d say is the most useful explanation we’ve got. The broad contours of the argument are pretty straightforward, but the full implications are not. (That’s something of an understatement. As I’ve discussed a few times before, a lot of very smart people have made incorrect statements about what this argument implies. In fact, while I’ll gladly admit we’ve hit the point of diminishing marginal returns, I still think there’s a lot we’ve yet to learn from this way of thinking.)

This activity was designed to illustrate both the general point that war can occur as a result of states taking (optimal) gambles and also to demonstrate two less intuitive implications of the argument: states who expect to do poorly in war are not necessarily any less likely to risk war; and states who are fairly sure their fait accompli will provoke military resistance may still execute them, even if said resistance would cause them ex post regret.


The scenario described by the two parts of the activity is identical to that depicted by the game-theoretic model discussed in the lecture. But whereas the lecture walks through a general solution to the model, identifying optimal strategies under all possible conditions, and thus involves a fair amount of algebra, the activity assigns concrete numbers to everything and so simplifies things greatly. In fact, while I allowed the students to consult their notes and/or the slides during the activity, as a handful did, the optimal strategies here are sufficiently straightforward that most students correctly identified them without doing so (and probably, in many cases, without having listened to the lecture before class.)

Of course, it helps that this time around, I didn’t throw things wide open the way I did with a previous activity. The only two options that make any sense (the largest land grab the blue type would be willing to live with, which would provoke a war if D happens to be red but bring a better payoff if they’re blue; and the largest land grab that the red type would tolerate, which ensures peace but not necessarily on the best possible terms) are identified for them. All they have to do is figure out which makes more sense.

As many correctly determined, it makes sense to gamble here. That’s not terribly interesting, in and of itself. But what one might overlook is that they just proved to themselves, through their own behavior, that it can make sense to risk war even if you know that, should the war that you genuinely hope to avoid occur, the outcome would be pretty terrible. In this case, grabbing 50% of the territory meant accepting a 30% chance of provoking a war that would leave you feeling as though you’d gained nothing at all (acquiring 10% of the territory but incurring costs that completely offset that gain). And yet most of them went for it. As they should have.

The second part is nearly identical to the first. However, here, any potential war would go pretty well for the challenger, even against the red type. The costs of war have even come down a bit. So it’s not surprising that even more of them decided to gamble here, taking 90% of the territory. Again, that’s not what I what I was trying to show. What I wanted them to focus on was that the vast majority of them went for the larger land grab despite the fact that they knew (or, at least, should have known) there was a 65% chance that they wouldn’t get away with it. As I hope was clear to at least some of them, taking 60% of the territory, which they’d have been sure to get away with, would certainly leave them better off than fighting a war against the red type would, since that would leave them feeling as though they’d acquired 50%. So even though the war they risked provoking wouldn’t prove disastrous, its occurrence would still entail ex post regret. It would be a war no one wanted. As most wars are.

As ever, I’m not sure everyone got what I was trying to convey. But I think most of them did. Hopefully, most of them will now be less inclined to confidently assert (the way so many do) that it makes no sense to involve yourself in a war you don’t expect to win, or to see a war that no one really wanted and conclude that some or all of the personalities involved must have been deficient in some way. As I discussed in the lecture, it’s entirely possible that those factors were at work in many historical cases. But we don’t know that. We can’t know that, at least not with the sort of confidence many exhibit. Because despite what many seem to believe, such outcomes can arise as the result of optimal decision-making.