Having begun in the 1960s, the calling into question of Keynesianism took place in the 1970s and 1980s. Part of this criticism involves the inadequacy of its microeconomic foundations. The critique was formulated by authors of very diverse theoretical horizons, among whom were several still regarding themselves as Keynes’s disciples. It was also led by those who were very critical of Keynesian theory. Robert Lucas, at first a Keynesian and then principal theoretician of the new classical macroeconomics, assumed leadership of the offensive. Traditional macroeconomics, as much Friedmanian as Keynesian-even though Lucas showed Friedman deference1-was left behind as the reconstruction of economic analysis, on the basis of the extension of the rationality postulate to include the acquisition of information and expectations, was witnessed.