Hopefully lessons about the first Great Depression, such as how the policies of the New Deal actually lengthened the depression, will be learned this time.
I've heard this so many times recently. The exact same argument used for exactly conflicting points of view. And every time it's brought up it is presented as an uncontroversial example of how X (or Y the exact opposite of X) works:
http://www.econlib.org/library/Enc/GreatDepression.html