Back in that Forking Garden

I’m skeptical of meditations on history that appeal to the now familiar butterfly effect. As a matter of mathematics, arbitrarily small differences in the starting points of certain dynamic systems have huge consequences. If the world and therefore history is a chaotic system, however, that just means that any alteration of boundary conditions whatsoever suffices to change everything after a while. But this notion is perfectly empty, first, because one can never test or exploit the sensitivity of the system because no one can change anything at all, and, second, because all changes, meaningful or meaningless, are equivalently potent in this hypothesis. So far as I can see, chaos theory has nothing to tell us about what makes historical events decisive. It can never help us figure out what would have happened if Grant had been drinking at Appomattox.

Counterfactual historians like to underline the quirkiness of history by suggesting that plausible alternative decisions would have led to vastly different outcomes. I have no quarrel with this procedure as a way of thinking about what’s at stake in history, though in many cases I think it is employed mostly as a prophylactic or postphylactic against the apparently unbustable ghost of Marxism. But counterfactual history, as practiced, actually presumes a high degree of rationality in human affairs. It is anything but a celebration of the sovereignty of chance. Only in a highly organized world is it possible for an individual or a few individuals to make a decision that has recognizable, if not entirely predictable consequences. The paths fork—the government of Italy chooses to invade France or it doesn’t—but the options don’t splinter into thousands or billions of outcomes at every moment. If Croesus crosses the river Halys, he doesn’t know whose kingdom will be put at hazard, but somebody’s will. Atoms, molecules, rocks, and animals just don’t have that kind of leverage.

Counterfactual history only makes sense if human affairs mostly make sense. Niall Ferguson may not be a Hegelian, but his methodology strongly implies that the “Real is pretty rational: the pretty rational is real.” That’s not a small matter, and raises the preliminary question of how a region of reality got predictable enough to be uncertain in a game-like way.