Ezra Klein makes the argument that there's no evidence that higher taxes on the wealthy hinder growth. In fact, there is evidence to the contrary, as Ezra points out with this graph:
When has the absence of evidence (or even evidence to the contrary) ever stopped a Republican from doing (or not doing) something (See: Iraq, Global Warming, et al)?
"Absence of evidence is not evidence of absence." --Donald Rumsfeld
"Appeal to ignorance -- the claim that whatever has not been proved false must be true, and vice versa (e.g., there is no compelling evidence that UFOs are not visiting the Earth; therefore UFOs exist -- and there is intelligent life elsewhere in the Universe. Or: there may be seventy kazillion other worlds, but not one is known to have the moral advancement of the Earth, so we're still central to the Universe.) This impatience with ambiguity can be criticized in the phrase: absence of evidence is not evidence of absence." -- Carl Sagan, The Demon-Haunted World: (Chapter 12 - The Fine Art of Baloney Detection)
Herein lies the rub. Republicans don't care about facts. They are not constrained by reality or science. They make up whatever they need and ignore everything to the contrary. So why do we try to reason with them logically? Seems like a waste of time.
One answer is that they must be mocked, ruthlessly and endlessly, for ignoring facts. This is why Stephen Colbert is so funny and necessary. Under Citizens United, facts mean even less, and money even more, which benefits the party that is weak on facts and strong on money.