The recent controversy over "Dynamic Scoring" shows the Republicans are still in love with the "Laffer Curve," the idea that cutting the tax rate on the highest brackets would generate so much an increase in the economy that the taxes on the new business at the new rates would more than make up for the loss of revenue from lower rates.
That has never happened, and most of us here on dKos know that it has never happened. What far fewer know, however, is that lower maximum rates have never been shown to increase the rate of growth of the US economy. (There was a Scandinavian government once that passed tax laws so restrictive that the total top tax rate accidentally ended up over 100%. It was soon revised. That was generally considered to have restricted the economy, but not even then were people stopped from doing things which cost them more in taxes than it gained them in pre-tax income.)
The economy grows almost always, and Republicans point out that it grew after tax cuts. (Feed your 4-year-old Frank's magic growth pills, and I will guarantee that he will be larger next year.) Not since the Kennedy tax cuts, however, has the rate of growth increased following such a cut, and the Kennedy tax cuts were only one of many economic reforms passed in that period.
In general, the rate of growth has decreased over time while the maximum tax rate has been slashed. The only prolonged period of growth that exceeds the post-war average in the recent past was under Bill Clinton, and Clinton raised taxes on the rich (quite moderately).
So, it is not only false to says that a tax cut is certain to accelerate economic expansion enough to pay for itself. It is false to say that it likely to accelerate economic expansion at all.
The record in Brownback's Kansas shows that dramatic tax cuts will balloon deficits. Even Republicans are noticing that.
(To be fair to Laffer, his version said that there was some point at which tax rates would bring in maximum revenues. On his sketch, the point looked like a 50% marginal rate. He never said that you could keep cutting taxes forever and the revenue would increase each time.)