Innovation and growth: What have we learnt from the robustness debate?

The recurrent issues of "non-robustness" and "scale effects" are discussed within a unified framework for the presentation of different generations of innovation-based growth models. With a certain proviso robust innovation-based growth models tend to end up with the long-run per capita growth rate pinned down by population growth. That is, the long-run prospect seems to be semi-endogenous growth. This is so also when essential non-renewable resources are taken into account. Semi-endogenous growth need not imply policy-invariant growth. Non-renewable resources may imply instability problems of an unfamiliar kind. The projected slowdown of population growth is likely to decrease future per capita growth as well as the discount rate relevant for evaluation of long-term environmental projects.