If they're right, it's good news for savers and investors. Secular stagnation doesn't just imply negative real returns on cash and higher-quality bonds, but also perhaps low returns on equities to the extent that it means weak economic growth.
But are they right? The question hinges upon another question: why are real long-term interest rates so low? Yields on 10-year index-linked gilts are now minus 0.6 per cent, compared with an average of 3.7 per cent between 1985 and 1997.