There is indeed another major reason that explains the big difference in the rate of labour productivity growth in Europe compared with the US, which in my view is a major policy issue, namely the fact that the European economy does not take advantage as does the US economy of all the opportunities offered in particular by the advances of science and technology including, but not exclusively, in the ICT sector.
I will now expand on the first aspect and try to bridge it to the problem that, in my view, undermines the policy benchmarking function of simple policy rules in unconventional monetary policy times like the present.