I'm enjoying Robert Cowley's anthology, What If, a large collection of counterfactual essays. What if the Assyrians hadn't gotten sick outside Jerusalem in 701? What if the Persians won Salamis? What if Churchill had been killed, and not merely scared, by a car accident in the 30's? What if Chang Kai-shek hadn't tried to dislodge the Communists and had let them remain Soviet clients in Manchuria?

It's a fun parlor game, but also cuts to the essential questions underlying historiography. Interestingly, even the pros play by two sets of rules. The counterfactual scruffies consider what might have happened if mistakes were not made, or if different decisions had been taken. Had Hitler attacked the Middle East instead of Russia, might the war have ended differently? The neats won't allow this: according to their rules, counterfactuals must depend on factors outside human control. The weather is everyone's favorite; it's possible to believe that Hitler had to attack Russia, or that Napoleon had to be emperor, but it's no longer tenable to believe that the Normandy invasion storm had to clear up. A butterfly might have decided otherwise....