David Friedman’s dinnertime conversations with his son Bill inspired the following hypothetical:

Imagine that someone in our future is equipped with a device capable of
delivering packages to the past. He makes a list of thirty or forty of
the most influential people in the U.S. as of (say) the 1850’s,
prepares for each a package of history books, and delivers the package
to the recipient’s desk a week or two before some prominent natural
event, such as an earthquake or eruption, is due to occur.

package includes a dozen identical color photographs and a cover
letter. The letter predicts in detail the event about to occur and
explains that the package is being sent in the hope of preventing a
very bloody war. The photographs could not have been produced with
mid-19th century technology; the hope is that they plus the prediction
will be enough to persuade at least some of the recipients that the
package really is from the future. What happens?

Father and son are both pessimistic:

Bill’s guess was that the deep South states would respond by
immediately seceding. My reaction–not inconsistent with his–was that
what the intervention has created is a high stakes game of Chicken.
Leaders in the North can tell those in the South that they might as
well surrender now, since the alternative is a long and bloody war that
they will lose. Leaders in the South can argue in response that the
North, knowing what the cost of the war will be, will have to back down
and let them go.

David adds:

It could make the plot of an interesting novel. If I were writing
it–not likely to happen–I would be inclined to show the intervenors
from the future as naive do-gooders who take it for granted that if
only both sides had known, the war would of course be averted.

I tremble at the thought of correcting the microeconomics of a pair of Friedmans.  But here goes.  In the real world of bluff and counterbluff, it is the mixed strategy equilibrium of the Chicken game that’s relevant.  In this mixed strategy equilibrium, the probability that each side plays War falls as the payoffs of (War, War) fall.  Since you only get (War, War) if both sides play War, the equilibrium probability of the bad outcome rapidly falls when the worst case scenario gets uglier.  The punchline: Basic game theory is on the do-gooders’ side.

But wait – there’s more.  Not only does basic game theory support the naive conclusion that pessimism about war is good for peace; so does basic history.  The standard story of World War I is that both sides thought they’d be “out of the trenches by Christmas” – and therefore blundered into carnage.  The standard story of the Cold War is that both sides realized that nuclear war would be devastating.  So they kept their fingers off their respective Buttons, and mankind weathered the storm.  You’ve probably seen the same mechanism in your own life: Deadlocks with bad consequences are a lot more likely to be resolved via compromise than deadlocks with trivial consequences.

I’m a pacifist and an economist.   And as far as I can tell, pacifists’ idealistic efforts to teach the world – and especially the young – about the horrors of war are eminently realistic.  Reading All Quiet on the Western Front and Barefoot Gen won’t turn every child against warfare.  But the more pessimistic the average person is about the effects of war, the more peaceful our world is likely to be.