The main reason for this may be the long history of research in an agreed paradigm using less than a handful of different approaches. For instance, as Governor Donald Kohn has pointed out last week, the basic framework for analysing inflation used by the Fed has remained fundamentally unchanged over the past 35 years.
He said “That basic framework is essentially the expectations-augmented Phillips curve introduced by Milton Friedman and Edmund Phelps in the late 1960s.”6 Of course, there has been a lively debate and substantial theoretical and empirical progress leading from the neoclassical synthesis in the spirit of Paul A. Samuelson and John R. Hicks in the late 1960s to the new classical theory focusing on real business cycles and, more recently, to the new Keynesian framework, which put nominal rigidities and market imperfections centre stage.