What I mean by this is that both long-termers and short-termers agree that the West has dominated the globe for the last two hundred years, but disagree over what the world was like before this. Everything revolves around their differing assessments of premodern history. The only way we can resolve the dispute is by looking at these earlier periods to establish the overall “shape” of history. Only then, with the baseline established, can we argue productively about why things turned out as they did.
