Those who simply repeat history are condemned to leave the rest of us to read all about that repetition in the news every morning.
The second reason is so we will understand how civilizations got to where they are today.
What should, say, the advisers to Lord Grey, the British foreign secretary, have told him a century ago?
Surely something like: Let’s not lose our heads; the Germans are a growing power who can be accommodated without losing anything essential to our well-being and, perhaps, shaping their direction; Serbian nationalism is an incident, not a ; the French are understandably determined to take back Alsace-Lorraine, but this is not terribly important to us—nor to them either, really, if they could be made to see that.
Studying history doesn’t argue for nothing-ism, but it makes a very good case for minimalism: for doing the least violent thing possible that might help prevent more violence from happening.
The real sin that the absence of a historical sense encourages is presentism, in the sense of exaggerating our present problems out of all proportion to those that have previously existed.
(The history of medicine is that no matter how many interventions are badly made, the experts who intervene make more: the sixteenth-century doctors who bled and cupped their patients and watched them die just bled and cupped others more.) What history actually shows is that nothing works out as planned, and that everything has unintentional consequences.
History doesn’t show that we should never go to war—sometimes there’s no better alternative.
Every writer, of every political flavor, has some neat historical analogy, or mini-lesson, with which to preface an argument for why we ought to bomb these guys or side with those guys against the guys we were bombing before.
But the best argument for reading history is not that it will show us the right thing to do in one case or the other, but rather that it will show us why even doing the right thing rarely works out.