R&D-based growth in the post-modern era

Conventional R&D-based growth theory suggests that productivity growth is positively correlated with population size or population growth, an implication which is hard to see in the data. Here we integrate microfounded fertility and schooling into an otherwise standard R&D-based growth model. We then show how a Beckerian child quality-quantity trade-off explains why higher growth of productivity and income per capita are associated with lower population growth. The medium-run prospects for future economic growth - when fertility is going to be below replacement level in virtually all fully developed countries - are thus much better than predicted by conventional R&D-based growth theory.