...while at the same time dismiss how someone else may "know" otherwise? Wouldn't you say thats a bit arrogant.
Those off shoring strategies exist SPECIFICALLY because of higher tax rates. Thats why they are designed and located where they are. They cost money to maintain. Raising taxes further just makes it more profitable to keep those strategies in place. Its a pretty standard course in B school nowadays.
There is equally as much evidence supporting Laffer as government revenues increased after Kennedy and Reagan tax >cuts>.
And this is not an argument of over-under taxation. If it were, I could easily say that the 47% of filers paying nothing are certainly UNDERtaxed...and that no one should turn a net profit from the federal income tax system. (thats going to be some 15% of filers IIRC).
Your historical evidence of better times under different tax structure also happened under a completely different structure of business/demand. Attributing all of the growth of middle class and bettering of wealth distribution simply to tax code is entirely too simplistic an argument.