A comparative approach to the study of Macroeconomics. In: Alessia Amighini, Emiliano Brancaccio, Francesco Giavazzi, Marcello Messori. A New Textbook Approach to Macroeconomics: a Debate

The "comparative" approach to the study of Macroeconomics was widely used during the 20th century. This method is based on the use of just one system of equations for all the theories examined. The transition from one theory to the other takes place simply through modification of the functional forms and reversal of the positions of exogenous and endogenous variables. The initial system of equations thus acts as a sort of stereogram: very different conclusions will be reached in terms of economic analysis and policy in relation to the viewpoint from which it is examined. While this method of comparison does not of course make it possible to examine the entire range of epistemological differences between the approaches compared, it presents the unquestionable advantage of immediacy by showing that apparently marginal changes in hypotheses can lead to completely different deductions. The essay "Anti-Blanchard. Un approccio comparato allo studio della macroeconomia" is an attempt to return to the use of this particular method of comparing economic theories also in the sphere of teaching (Brancaccio 2012). Despite its apparently challenging title, it makes no claim to replace the celebrated mainstream textbook of Blanchard, Amighini and Giavazzi (2010) but is designed rather to stand alongside it. The purpose is to show how simple modifications to the initial hypotheses of the dominant macroeconomic model can lead to substantial reversal of the logical relations characterising it.