Large and sustained differences in marginal products of capital (MPKs) across countries are sharply at odds with the core implications of the neoclassical framework. Lucas (1990) and many subsequent studies have examined reasons for this MPK differential. In a recent contribution, Caselli and...

In this paper I study the optimal control path for a (capital or pollution) stock which accumulates time with a lag to its control. It is shown that the optimal control path is non-monotonic and cyclical in general, but it is monotonic if the objective function is additively separable in the...