“Free trade’s just a dandy concept/Advertisers tell us so/Don’t you question, don’t you doubt it/You’re so stupid. You don’t know.” So goes a song Sherrod Brown composed on his guitar back in 1993, when he was a freshman congressman from Ohio helping lead the fight against ratifying the North American Free Trade Agreement. The new president, Bill Clinton, was a Democrat, too, and he had agonised during his campaign over the trade deal, negotiated by his Republican predecessor. He eventually came out in support of it while promising to strengthen its protections for workers and the environment. The new protections did not go nearly far enough for Mr Brown, and his song expressed his aggravation with what he saw as a blinkered and patronising uniformity of elite opinion. In the end Mr Clinton rallied enough Democrats to join with most Republicans to ratify the treaty.