First, the modern hope in progress depended on the assumption that reason would be used in the service of humanity, or more briefly, that humans were innately good or at least were being transformed in that direction. As the nineteenth century moved on into the twentieth, this assumption looked increasingly implausible. The First World War (1914–1918) taught Europeans that even the countries most influenced by the Enlightenment could engage in tremendous amounts of pointless slaughter. During the