Historian Scott Trask of the Mises Institute has published a great article on 10 economic falacies that have permeated their way through public thinking. Myth #1 was the broken window, which is basically the idea that a disaster has a positive effect on the economy. He also discusses the myth that war is a boon on the economy. The basic idea behind the myth is that a disaster like an oil spill gets double-counted when calculating GDP, because there is the initial outlay in the oil and also the cost of cleaning it up.