Bangladesh, Feb. 7 -- There is a familiar pathology in political decline: leaders begin narrating reality rather than engaging it. Richard Nixon reached that stage when he started invoking “the President” as a third-party authority, a rhetorical trick meant to confer grandeur and inevitability on decisions that were, in truth, unraveling. Last week in Iowa, Donald Trump dipped into the same well. “Just after one year of President Trump, our economy is booming,” he announced. “Incomes are rising. Investment is soaring. Inflation has been defeated.”

The problem is not tone. It is the truth. Nearly every claim collapses under modest scrutiny.

This is not a partisan complaint, nor the reflexive anti-Trump...