First, there’s little evidence they will supercharge the economy. Modeling of a recent plan put forward by Rep. Dave Camp (R-Mich.), the outgoing Ways and Means chairman, suggests it would increase the economy’s size by less than 1 percent over a decade. Second, the income gains from modestly faster growth might not reach the middle class, where after-tax income has been stagnant for nearly a decade. The Congressional Budget Office recently found that top income growth has been five times faster than middle-income growth over the past 30 years.

Finally, sharply cutting top rates will lose the government trillions in revenue at a time the national debt is at historically high levels — unless, that is, lots of tax breaks are also eliminated. But many of those — such as the Earned Income Tax Credit — benefit middle- and working-class Americans, which is why more than 40 percent pay no federal income taxes, according to the Tax Policy Center.

Surely Republicans wouldn’t raise taxes on the beleaguered middle to help pay for high-end tax cuts? Some might. Recently Stephen Moore, chief economist at the GOP-aligned Heritage Foundation, argued that tax reform should “ensure that everyone — except the very poor — pays at least some income tax.” Keep in mind that according to the 2012 exit polls, Mitt Romney lost to Obama 86 percent to 16 percent among voters who most valued empathy in their presidential pick. Is the party shooting for 100-0 next time around? Hillary Clinton would like to know.