Is declining productivity inevitable ?

Fertility has been declining on all continents for the last couple of decad es and this development is expected to continue in the future. Prevailing i nnovation-based growth theories imply, as a consequence of scale effects fr om the size of population, that such demographic changes will lead to a maj or slowdown in productivity growth. In this paper we challenge this pessimi stic view of the future. By allowing for endogenous human capital in a basi c R&D driven growth model we develop a theory of scale-invariant endogenous growth according to which population growth is neither necessary nor condu ctive for economic growth.