Why are some countries rich while others remain poor? The Solow model predicts that countries with lower capital per worker should grow faster due to diminishing returns to capital, leading to convergence.
Conditional convergence holds only among peer groups with similar institutions and savings rates—such as OECD countries or US states. However, unconditional divergence occurs globally; the rich-poor gap widened from 3:1 in 1820 to over 20:1 today, proving catch-up is not automatic.
Growth Failures explain why some nations miss out:
- Institutions: Extractive systems block investment; inclusive property rights foster growth.
- Geography: Tropical barriers, disease, and being landlocked impose penalties.
- Human capital: Health and skills limit labour quality.
- State capacity: Weak or predatory governance strangles enterprise.
Why Convergence Fails
Total factor productivity (TFP) explains most cross-country income gaps. Rich nations are not just capital-heavy; they use all inputs more productively through better technology, management, and trust.
Since 1990, The Great Convergence has been driven by China and India, shifting global distribution as Asia rapidly catches up.
| Scope | Result |
|---|---|
| Similar institutions (OECD) | Poor members grow faster, convergence |
| Full world sample | No automatic catch-up, divergence common |
| The difference | Institutions, human capital, savings, stability |
Pitfall: The Lucas paradox—capital failing to flow to capital-poor regions—proves that institutional barriers bind development far more than mere capital scarcity.