What causes long-run growth differences between countries?

Per-capita income differs by more than a factor of 100 across countries. Solow-type growth accounting attributes most of the variation to differences in 'total factor productivity', but what drives productivity itself is contested.

Institutions, geography, culture, human capital and historical shocks all feature in modern theories (Acemoglu-Robinson, Diamond, Romer). A predictive theory remains out of reach.