The point I want to emphasize, however, is that historical reality is more complex than the idea of a completely stable capital-labor split suggests. The Cobb-Douglas hypothesis is sometimes a good approximation for certain subperiods or sectors and, in any case, is a useful point of departure for further reflection. But this hypothesis does not satisfactorily explain the diversity of the historical patterns we observe over the long, short, or medium run, as the data I have collected show.
