Scott Walker, the governor of Wisconsin, is said to be a rising contender for the Republican presidential nomination. So, on Wednesday, he did what, these days, any ambitious Republican must, and pledged allegiance to charlatans and cranks.

For those unfamiliar with the phrase, “charlatans and cranks” is associated with N. Gregory Mankiw, a professor at Harvard who served for a time as George W. Bush’s chief economic adviser. In the first edition of his best-selling economics textbook, Mr. Mankiw used those words to ridicule “supply-siders” who promised that tax cuts would have such magic effects on the economy that deficits would go down, not up.

But, on Wednesday, Mr. Walker, in what was clearly a rite of passage into serious candidacy, spoke at a dinner at Manhattan’s “21” Club hosted by the three most prominent supply-siders: Art Laffer (he of the curve); Larry Kudlow of CNBC; and Stephen Moore, chief economist of the Heritage Foundation. Politico pointed out that Rick Perry, the former governor of Texas, attended a similar event last month. Clearly, to be a Republican contender you have to court the powerful charlatan caucus.

So a doctrine that even Republican economists consider dangerous nonsense has become party orthodoxy. And what makes this political triumph especially remarkable is that it comes just as the doctrine’s high priests have been setting new standards for utter, epic predictive failure.