Though the current economy is among the strongest of the past 50 years, critics of President Trump’s transformational trade policies continue to insist that the tariffs are hindering rather than helping the boom. Citing forecasts like the latest from the Federal Open Market Committee, these critics have tarred the Trump tariffs as price inflators, job killers and growth destroyers. Yet with each new tariff—on dishwashers, solar panels, aluminum, steel and more than $300 billion of Chinese imports—the economy remains robust, wages continue to rise, and inflation stays muted.

Why...