[Krugman] One way to think about the global crisis is a vast excess of desired savings over willing investment. We have a global savings glut. Another way to say it is we have a global shortage of demand. Those are equivalent ways of saying the same thing. So we have this global savings glut, which is why there is, in fact, no upward pressure on interest rates. There are more savings than we know what to do with. If we ask the question “Where will the savings come from to finance the large US government deficits?,” the answer is “From ourselves.” The Chinese are not contributing at all.
Those extra savings are, in effect, the savings that America has wanted to make anyway, but that US business is not willing to invest under current conditions. That is the way Keynesian policy works in the short run. It takes excess desired savings and translates them into some kind of spending. If the private sector won't do it, the government will. There is actually no contradiction between the Federal Reserve's actions and the actions of the US government with a fiscal stimulus. It's very much necessary to do both. By buying a lot of private securities, the Federal Reserve is essentially going out there and playing the role that the private banking system is no longer playing properly; by engaging in investment, the federal government is playing the role that businesses are not now willing to play. All that debt-financed spending on infrastructure by the Obama administration is basically filling the hole left by the collapse in business investment in the United States. There is not an excess demand for savings that is going to drive up interest rates. The only thing that might drive up interest rates—and this is a real concern—is that people may grow dubious about the financial solvency of governments.
Also see Delong on the talk.