Of course, Mr Krugman knew what I meant. "The only thing that might drive up interest rates," he acknowledged during our debate, "is that people may grow dubious about the financial solvency of governments." Might? May? The fact is that people - not least the Chinese government - are already distinctly dubious. They understand that US fiscal policy implies big purchases of government bonds by the Fed this year, since neither foreign nor private domestic purchases will suffice to fund the deficit. This policy is known as printing money and it is what many governments tried in the 1970s, with inflationary consequences you do not need to be a historian to recall.
It was Keynes who noted that "even the most practical man of affairs is usually in the thrall of the ideas of some long-dead economist". Today the long-dead economist is Keynes, and it is professors of economics, not practical men, who are in thrall to his ideas.