Episode 106: Theories of Economic Growth and Development

Harrod-Domar

The Harrod-Domar model, a pioneering macroeconomic framework, posits that economic growth is driven by capital accumulation. This model suggests that increased investment in infrastructure and technology leads to proportional growth in output, emphasizing the role of savings in boosting capital 1. However, James Fodor highlights its limitations, such as the unrealistic assumption of constant returns to capital and the exclusion of labor as a growth factor 2.

The Harrod-Domar model is now regarded as inadequate in describing growth, partly because empirically it just doesn't hold up that capital accumulation is enough for growth.

To address these shortcomings, the Solow-Swan model was developed as an alternative.

   

Solow-Swan

The Solow-Swan model builds on the Harrod-Domar framework by incorporating both capital and labor, using a Cobb-Douglas production function. This model predicts that economies will grow through capital accumulation, but with diminishing returns as capital increases without a proportional rise in labor 3. Fodor explains that this model introduces the concept of conditional convergence, where poorer countries grow faster than richer ones if they share similar technological levels 4.

The Solow-Swan model actually predicts conditional convergence, which means if two countries are basically the same, then the one that is poorer will be able to grow faster than the one that is richer.

Despite its insights, the model has limitations, particularly in explaining long-term growth beyond capital and labor dynamics.

   

Endogenous Growth

Endogenous growth models, including Romer's spillovers model, attempt to incorporate technological progress into economic growth theories. These models suggest that technological advancements can lead to sustained growth by increasing returns to scale and improving productivity through mechanisms like learning by doing 5. Fodor6.

I think it was high on promise and small on delivery, because it's really not clear what we've learned about how economic growth occurs that we didn't already know from Romer's spillover model in the eighties.

Despite their promise, these models struggle to explain income disparities between countries, focusing more on growth processes than on their origins.