Libertarian-minded Republicans love to claim that free trade is essential to economic growth, and through the postwar and Reagan-era booms, it certainly didn’t hurt. But was it really a — let alone the — key variable in generating growth? It’s hard to make that case when the United States had some of the highest tariffs in the world through the era of economic take-off that transformed America in the decades following the Civil War. The history of that era shows that high tariffs can be quite compatible with rapid growth, at least sometimes and under some conditions.

But companies have grown used to doing business without tariffs increasing their costs, and they don’t want to pass those costs onto consumers out of fear that doing so will hurt sales. The anti-tax ideology of the GOP, meanwhile, gives Republican politicians a ready-made way to make the case against tariffs without having to sound like they’re doing the bidding of CEOs and shareholders. Tariffs raise government revenue, and that makes them a form of taxation. Therefore they are bad.

Will that simplistic syllogism (with its assumed and unargued-for minor premise: “taxation is always bad”) prove as persuasive with voters as it is with politicians attempting to please business lobbyists? We really don’t know, because no prominent Republican has challenged it for decades — at least until now.