An uncertainty-based explanation of symmetric growth in Schumpeterian growth models

We provide a re-foundation of the symmetric growth equilibrium characterizing the research sector of all vertical R&D-driven growth models. This result does not rely on the usual assumption of a symmetric expectation on the future per-sector R&D expenditure. Indeed, with this structure of expectations, returns in R&D are equalized, and agents turn out to be indifferent as to where targeting research: hence, the problem of the allocation of R&D investments across sectors is indeterminate. In line with the ’true’ Schumpeterian perspective, we solve this indeterminacy by allowing for decision makers strictly uncertain about the future per-sector distribution of R&D efforts. By using the Gilboa-Schmeidler’s MEU decision rule, we prove that the symmetric structure of R&D investment is the unique rational expectations (RE) equilibrium compatible with uncertainty-averse agents adopting a maximin strategy.