From Tyler Cowen:
I conclude that economics is not yet a science. Economics is most like a science when people do not care about the outcome of the argument.
This is something that Russ Roberts has been saying for a while. It is almost impossible to do any real tests of macroeconomic theory. Even when experiments (aka policy) are done, there are too many variables to nail down causes and effects beyond first order effects, sometimes that’s not even obvious.