O modelo de Harrod: natureza das expectativas de longo prazo, instabilidade e não-linearidade

Harrod´s model: nature of long term expectations, instability and no linearity The different versions of Harrod´s growth model have always been the subject of controversy and mistaken interpretations: in this paper, we intend to show how Harrod, from 1938 onwards, provides the elements to build a dynamical analysis using Keynes´ theoretical tools: this means to provide an endogenous explanation for instability, for the existence of a reversal point as well as for the modes of regulating the system. It will be shown, also, how Harrod translates, in a dynamical language, Keynes´ static analysis developed in his General Theory . In the first section, we investigate the relations among effective demand, the equilibrium´s stability and the nature of expectations as they are presented in the General Theory . In the second section, we explain how, from a non linear conception of economic processes, Harrod defines many instability principles along with some modalities of regulating the system.