Technological opportunity, long-run growth and convergence

We derive an R&D-based semi-endogenous growth model where technological progress depends on the available amount of technological opportunity. Incremental innovations provide direct increases in the knowledge stock but they reduce technological opportunity and thus the potential for further improvements. Technological opportunity can be renewed only by radical innovations (which have no direct impact on factor productivity). Investigating the model for its implications on economic growth leads to two basic observations. One, in the long-run, a balanced growth path with a consstant and semi-endogenous long-run economic growth rate exists only in a specific knife-edge case which implies that technological opportunity and knowledge grow at equal rates. Two, the transition need not be monotonic. Specifically, we show under which conditions our model generates endogenous business cylces via complex dynamics without uncertainty.