Sitting back is not an option.

The problem is, we have very, very few examples to test on:  America during the Great Depression, and Japan in the 1990s.  And neither America nor Japan managed to stimulate their way out of their troubles.  You can argue--and many do--that this is because we, and they, didn't stimulate enough.  That may be true.  But unless you can forward test your theory, it's a just so story . . . as we just painfully found out about the "It was all the Fed's fault" narrative of the 1930s banking collapse.  There is no excuse for calling people who question your highly theoretical model fools and charlatans.

What we've got, since Japan really never did emerge from its lost decade, is basically one fact: America entered World War II in a depression, and emerged from World War II without one.  Hopefully, the relevant variable was the massive, massive amount of spending, rather than any of the other explanations one can plausibly build about the effect of Total War on depressions--like the slaughter of some of your excess labor force, or the substitution of more immediate fears of being killed for panic about the financial future.

That was Megan McArdle.  

The fact that we don't have successful lessons from the past to lean on, and learn from, is why I am so convinced that we need the Warren Buffett honesty as we tackle the recession.  Buffett remarked that:

The answer is nobody knows. The economists don’t know. All you know is you throw everything at it and whether it’s more effective if you’re fighting a fire to be concentrating the water flow on this part or that part. You’re going to use every weapon you have in fighting it. And people, they do not know exactly what the effects are. Economists like to talk about it, but in the end they’ve been very, very wrong and most of them in recent years on this. We don’t know the perfect answers on it. What we do know is to stand by and do nothing is a terrible mistake or to follow Hoover-like policies would be a mistake and we don’t know how effective in the short run we don’t know how effective this will be and how quickly things will right themselves. We do know over time the American machine works wonderfully and it will work wonderfully again.