Economic Stimulus - Does it really work?

Lots of talk these days about the government providing "economic stimulus" to the economy. Ever since my first year economics class in university, I've heard that when the goverment spends money, its effect is multiplied across the economy and it provides great benefits. I always thought that logic was flawed, as it overlooked where the government got that money and the negative effects caused by it.

That idea was started by a British economist named John Maynard Keynes (pronounced "Kains") and has since become known as Keynesian economics. It seems to increase in popularity every time there is an economic downturn, and given the severity of this downturn, its popularity is really surging now.

Now someone named Dan Mitchell has explained the flaw with Keynesian economics much clearer than I ever could. He also explains the track record of this strategy since the 1930's.