Paul Krugman explains why we can't settle for stabilizing the economy, and says unless there's a bigger economic stimulus package, high unemployment is here to stay for a long, long time:

The effects of the stimulus will build over time — it’s still likely to create or save a total of around three million jobs — but its peak impact on the growth of G.D.P. (as opposed to its level) is already behind us. Solid growth will continue only if private spending takes up the baton as the effect of the stimulus fades. And so far there’s no sign that this is happening.

So the government needs to do much more. Unfortunately, the political prospects for further action aren’t good.

What I keep hearing from Washington is one of two arguments: either (1) the stimulus has failed, unemployment is still rising, so we shouldn’t do any more, or (2) the stimulus has succeeded, G.D.P. is growing, so we don’t need to do any more. The truth, which is that the stimulus was too little of a good thing — that it helped, but it wasn’t big enough — seems to be too complicated for an era of sound-bite politics.

But can we afford to do more? We can’t afford not to.

High unemployment doesn’t just punish the economy today; it punishes the future, too. In the face of a depressed economy, businesses have slashed investment spending — both spending on plant and equipment and “intangible” investments in such things as product development and worker training. This will hurt the economy’s potential for years to come.

Deficit hawks like to complain that today’s young people will end up having to pay higher taxes to service the debt we’re running up right now. But anyone who really cared about the prospects of young Americans would be pushing for much more job creation, since the burden of high unemployment falls disproportionately on young workers — and those who enter the work force in years of high unemployment suffer permanent career damage, never catching up with those who graduated in better times.

Even the claim that we’ll have to pay for stimulus spending now with higher taxes later is mostly wrong. Spending more on recovery will lead to a stronger economy, both now and in the future — and a stronger economy means more government revenue. Stimulus spending probably doesn’t pay for itself, but its true cost, even in a narrow fiscal sense, is only a fraction of the headline number.

O.K., I know I’m being impractical: major economic programs can’t pass Congress without the support of relatively conservative Democrats, and these Democrats have been telling reporters that they have lost their appetite for stimulus.

But I hope their stomachs start rumbling soon. We now know that stimulus works, but we aren’t doing nearly enough of it. For the sake of today’s unemployed, and for the sake of the nation’s future, we need to do much more.