URL des Documents de travail : http://centredeconomiesorbonne.univ-paris1.fr/documents-de-travail-du-ces/Documents de travail du Centre d'Economie de la Sorbonne 2017.42 - ISSN : 1955-611XWe illustrate how the Lucas Critique was called into question by Keynesian macroeconomists during the 1970s and 1980s. Our claim is that Keynesians' reactions were carried out from a pragmatic approach, which addressed the empirical and practical relevance of the Critique. Keynesians rejected the Critique as a general principle with no relevance for concrete macroeconometric practice; their rejection relied on econometric investigations and contextual analysis of the U.S. 1970s stagflation and its aftermath. Keynesians argued that the parameters of their m...