Peop le often say things like, “If we go down that path there’s no going back,” or, “Now that it’s happened, we’re stuck with it.” Such phrases recognise something about the way events acquire their own momentum: the fact that something happens once means that it is more likely to happen again; the most important factor in history is, in a sense, history itself. Economics has a phrase for this idea: “path-dependence.” The concept is particularly useful as a way of explaining why certain technologies stick—the classic example being the Qwerty keyboard layout. The designers of early typewriters settled upon this configuration on the basis that it physically separated the most common two-letter sequences, thereby minimising the risk of the keys getting stuck. In other words, the advantage of the Qwerty system was that it made typing inconvenient. Obviously, once electric typewriters were invented, the logic behind the system disappeared. But millions of people had learned to type this way—so why change it? Another example of path-dependence is the existence of countries that drive on the left side of the road; this, too, is a phenomenon that only history—in the form of the British empire—can explain.
Path-dependence, then, is a way of accounting for the persistence of imperfection. In this sense, it is a cousin of conservatism, although while conservatism says that the way things have always been done is best, path-dependence simply accounts for them having to be that way. The concept’s weakness is that it runs the risk of banality. In its broadest sense, all it means is: “history matters.”