Looking into the black box of Schumpeterian Growth Theories: an empirical assessment of R&D races

This paper assesses whether the most important R&D technologies at the roots of second-generation Schumpeterian growth theories are consistent with patenting and innovation statistics. Using US manufacturing industry data, we estimate various systems of simultaneous equations modeling the innovation functions underlying growth frameworks based on variety expansion, diminishing technological opportunities and rent protection activities. Our evidence indicates that innovation functions characterized by the increasing difficulty of R&D activity fit US data better. This finding relaunches the debate on the soundness of the new Schumpeterian strand of endogenous growth literature.