Neither neo-Keynesians nor supply-siders focus on the true remedies for this persistent drop in investment spending. Our societies urgently need more investment, particularly to convert heavily polluting, energy-intensive, and high-carbon production into sustainable economies based on the efficient use of natural resources and a shift to low-carbon energy sources. Such investments require complementary steps by the public and private sectors.
Jeffrey Sachs is absolutely correct in his criticism of both camps of economists (supply-siders and neo-Keynesians). What we need is radical reform of our economies and of economists.