[gozur88]

This. The real problem with making definitive statements in economics is you can't run double-blind experiments.

Let's say you create some sort of giant monetary stimulus package. If the economy gets worse proponents will say "Whew! Just think how terrible things would have been without our stimulus package," and opponents will say "Things got worse because of the stimulus package!"

There's no way to know who's right. The best you can do is make imperfect models to encapsulate trillions of individual decisions people make. But that's not proof.