"huge government deficits could fail to raise interest rates in a depressed economy ... is what Econ 101 said – and it has been completely right. Basic IS-LM macro also said that under these conditions printing lots of money would not be inflationary, and that cutting government spending sharply would cause the economy to shrink. All of this has come true. So Econ 101 has done just fine ..."Note, however, that Krugman basically believes that this is the case because the economy is in a liquidity trap, and the natural rate of interest for him is negative. That is, the rate of interest that would stimulate enough investment to bring about full employment savings is below zero. As I have argued here there are several empirical and logical reasons why one should doubt that kind of imperfectionist argument.
So, yes the Old Keynesians policy prescriptions do work, and have done quite well, even if their theories do fail miserably, as much as any other neoclassical approach that presumes that markets work by the magic of supply and demand producing optimal outcomes.
And that is also why what we need is not more monetary stimulus, or any hocus pocus to convince investors that inflation is going to be higher. We need more demand. And as Paul Davidson said in his reply to Tyler Cowen, only the government can do this now:
"if the government were to let contracts for, say, $1 trillion to private enterprise to rebuild our failing highways, bridges, and municipal water and sewage systems, and provide resources for our shrinking public and higher education systems, this would quickly restore companies’ confidence in the profit opportunities that are available if they hire workers and buy materials from other United States companies. When these newly hired workers go out and spend their wages, the confidence of United States retailers would immediately surge as these additional customers break down the doors to get at the merchandise on the shelves. Nothing will build the confidence and trust of business and workers quicker than the continuous ringing of cash registers."So Paul, that has complained about Econ 101 for a long time, is quite correct. We need spending and not the inflation expectations fairy.
PS: On my views on the ISLM go here.