But now it looks as if voodoo is making a comeback. At the state level, Republican governors — and Gov. Sam Brownback of Kansas, in particular — have been going all in on tax cuts despite troubled budgets, with confident assertions that growth will solve all problems. It’s not happening, and in Kansas a rebellion by moderates may deliver the state to Democrats. But the true believers show no sign of wavering.

Meanwhile, in Congress Paul Ryan, the chairman of the House Budget Committee, is dropping broad hints that after the election he and his colleagues will do what the Bushies never did, try to push the budget office into adopting “dynamic scoring,” that is, assuming a big economic payoff from tax cuts.

So why is this happening now? It’s not because voodoo economics has become any more credible. True, recovery from the 2007-9 recession has been sluggish, but it has actually been a bit faster than the typical recovery from financial crisis, despite unprecedented cuts in government spending and employment. In fact, the recovery in private-sector employment has been faster than it was during the “Bush boom” last decade. At the same time, researchers at the International Monetary Fund, surveying cross-country evidence, have found that redistribution of income from the affluent to the poor, which conservatives insist kills growth, actually seems to boost economies.

But facts won’t stop the voodoo comeback, for two main reasons.

First, voodoo economics has dominated the conservative movement for so long that it has become an inward-looking cult, whose members know what they know and are impervious to contrary evidence. Fifteen years ago leading Republicans may have been aware that the Clinton boom posed a problem for their ideology. Today someone like Senator Rand Paul can say: “When is the last time in our country we created millions of jobs? It was under Ronald Reagan.” Clinton who?

Second, the nature of the budget debate means that Republican leaders need to believe in the ways of magic. For years people like Mr. Ryan have posed as champions of fiscal discipline even while advocating huge tax cuts for wealthy individuals and corporations. They have also called for savage cuts in aid to the poor, but these have never been big enough to offset the revenue loss. So how can they make things add up?