World histories are shaped by the questions their authors ask. The great Toynbee asked how civilizations developed
and declined. Anthropologists once led historians to ask how the world's cultures were similar and different.
Recently many historians have followed William McNeill in asking how the peoples of the world interacted and
became one.
An older tradition, strains of which were called Christian, Whig, positivist, and Marxist, asked how the entire
course of world history changed, evolved, or progressed. While sometimes dismissed as naive by cautious
twentieth-century specialists, this older tradition continues for a simple reason. It asks the questions most of us
want answered. What have been the most important changes in human history? How have these changes come
about?