Biology, not ideology, sets history's outer limits

The Durants open by insisting that history is ultimately a branch of biology: three biological facts — the struggle for existence, the drive to reproduce, and the tendency of the strong or capable to accumulate more than the weak — shape every political and economic arrangement humans have ever built. Wars, they argue, are essentially biology's competition for resources scaled up to the level of nations, and the eternal gap between rich and poor reflects unequal natural endowments of energy, intelligence, and ambition rather than any conspiracy.

This grounding matters because it explains why so many attempts at radical social redesign — utopian communities, revolutionary redistributions — eventually drift back toward inequality and hierarchy. The Durants aren't defending inequality morally; they're arguing that any system ignoring biological variation among people is building on sand. Nature, they write, doesn't care about equality, only about survival and adaptability.

Takeaway: no political system survives long if it pretends humans are biologically interchangeable.