During the Obama administration, he warned that the Fed was sowing the seeds of hyperinflation. “Zero interest rates haven’t helped the economy,” Mr. Moore told The Washington Post in 2015. Following Mr. Trump’s election, Mr. Moore executed a quick U-turn. He began to insist that lower interest rates were just what the economy needed. Mr. Trump reportedly settled on Mr. Moore after he was shown an article Mr. Moore co-wrote earlier this month making that case.

Mr. Moore has not argued that he changed his mind because he realized he was wrong, or because the facts changed. Indeed, on another question of public policy, he has maintained a politically convenient position despite the accumulation of facts to the contrary. He is a stalwart evangelist for the unsupported belief that tax cuts cure slow growth.

The state of Kansas took Mr. Moore’s advice on fiscal policy in 2013, adopting a set of tax cuts recommended by Mr. Moore and his longtime collaborator Arthur Laffer. The two men promised a “near immediate” increase in economic growth. Instead, the state’s economy languished and the state government fell into a funding crisis. In the course of the subsequent debate, the editorial page editor of The Kansas City Star announced that Mr. Moore had misstated so many facts that she would no longer publish his contributions in the paper.

There is a legitimate debate to be had about the level of interest rates. Many economists, both liberals and conservatives, shared Mr. Trump’s concerns about the Fed’s move toward higher rates last year. The Fed itself has decided to suspend further rate increases.

But that is no reason to let Mr. Trump install a loyalist at the Fed. The public interest is best served by appointing thoughtful and experienced policymakers to the Fed’s board, and then standing back and letting them do their best. Politicians, always looking to the next election, tend to want faster economic growth in the near term without particular regard for the long-term consequences. Mr. Trump reportedly has dismissed concerns about the rise of the federal debt, for example, by telling advisers, “Yeah, but I won’t be here.”