It comes not from a professional economist but from Warren Buffet, here goes:
whether tax cuts work or not. There is all of this academic debate
among economists. What do you think? Is that the right way to go with
stimulus and tax cuts?
WB: The answer is nobody knows. The
economists don’t know. All you know is you throw everything at it and
whether it’s more effective if you’re fighting a fire to be
concentrating the water flow on this part or that part. You’re going to
use every weapon you have in fighting it. And people, they do not know
exactly what the effects are. Economists like to talk about it, but in
the end they’ve been very, very wrong and most of them in recent years
on this. We don’t know the perfect answers on it. What we do know is to
stand by and do nothing is a terrible mistake or to follow Hoover-like
policies would be a mistake and we don’t know how effective in the
short run we don’t know how effective this will be and how quickly
things will right themselves. We do know over time the American machine
works wonderfully and it will work wonderfully again.
Sadly, that's about as scientific as we've been able to get.