Endogenous Growth Theory
The theory that long-run economic growth is driven by internal factors like innovation and human capital.
What is Endogenous Growth?
Endogenous growth theory is a macroeconomic framework, developed by Paul Romer and Robert Lucas in the 1980s, holding that long-run economic growth is determined by internal (endogenous) factors within the economic system — particularly human capital accumulation, technological innovation, research and development, and knowledge spillovers — rather than by exogenous forces outside the model. Unlike the earlier Solow-Swan model, where growth eventually stops unless driven by exogenous technological change, endogenous growth models generate sustained growth from deliberate investments in knowledge and skills. The theory has significant policy implications: it justifies government subsidies for education, R&D, and innovation, as these activities have positive externalities that private markets alone would underprovide.
Example
Silicon Valley's emergence illustrates endogenous growth: R&D investment at Stanford and UC Berkeley generated knowledge spillovers to nearby technology firms; those firms' profits funded further R&D; engineers moved between companies, diffusing knowledge; and successful startups trained new entrepreneurs. This self-reinforcing cycle of knowledge accumulation and innovation drove decades of productivity growth consistent with endogenous growth theory's predictions.