Now suppose that we had a way to raise the multiplier by more than half, from 1.8 to 2.8. The same fiscal stimulus would now produce an increase in GDP of $2.8 trillion--quite a difference. Nice deal if you can get it.
In fact you can. It is pretty easy to increase the multiplier; just raise import tariffs by enough so that the marginal propensity to import out of income is reduced substantially (to zero if you want the multiplier to go all the way to 2.8). Yes, yes, import protection is inefficient and not a very neighborly thing to do--but should we really care if the alternative is significantly lower growth and higher unemployment?
That's Dani Rodrik talking, words for which he's earned an immediate demotion from the relevant links section. Presumably I don't need to tall you how stupid that is. If you read the rest of the article, he suggests some other policies - e.g. a large Tobin tax - that are first-order equivalent.
Also check out A Stitch in Haste on a recent tax initiative in New York City.