Vecchie e Nuove Controversie sulla Curva di Phillips

This paper provides an overview of old and new debates on Phillips curve. The “coming-back” of Phillips curve is here reconsidered by reframing from the start the “accelerationist” controversy in the NCM approach of potential (or natural) GDP. This allows to focus on two points 1.- the mechanism for setting prices and wages, and in particular the role of the hypothesis of monopolistic competition; 2. - the limits of the very notion of an aggregate demand curve consistent with an inflationist equilibrium, and the reasons why the aggregate demand must be reformulated in a way that the transmission mechanism of monetary policy can be represented according to the Fisher’s notion of the real interest rate. The point 2 offers an explanation for why Keynesian models have been reformulated as Keynesian models of rational expectations. An “ad hoc” baseline model shows the effects of monetary policy and the role of simple Taylor’s rules for stabilizing the dynamics of inflation. However “ad hoc” macroeconomic models are opened to the Lucas’ critique and this motivates the adoption of dynamic general equilibrium modelling approach. New Keynesian models of Phillips curve share with the Real Business Cycle approach a dynamic stochastic general equilibrium framework. A detailed reconstruction of microeconomic foundations of the NKPC allows examining the properties and the limits of this approach, the proposals for overcoming these limits and criticisms about such proposals. These points are currently objects of a lively debate. The paper concludes by also discussing the actuality of NKM as business cycle theory.