Argument that Western history is explained by the fall of the Roman Empire: it fostered intense political competition which, in turn, explains much else.
Hardened by conflict, the European states became more integrated, slowly morphing into the nation-states of the modern era. Universal empire on a Roman scale was no longer an option. Like the Red Queen in Alice in Wonderland, these rival states had to keep running just to stay in place – and speed up if they wanted to get ahead. Those that did – the Dutch, the British – became pioneers of a global capitalist order, while others laboured to catch up. . . .
They’re deeply rooted in the fact that, after Rome fell, Europe was intensely fragmented, both between and within different countries. Pluralism is the common denominator.