In recent weeks, Donald Trump’s pursuit of a border wall between the United States and Mexico has worked its way back in time — to the Middle Ages. Trump has happily agreed that his proposal is a distinctly "medieval solution." "It worked then," he declared in January, "and it works even better now." That admission proved an invitation to critics, who inveighed against the wall as, in the words of the presidential hopeful Senator Kamala Harris, Trump’s "medieval vanity project."

The response from medievalists was swift and withering — not just for the president, but also for his opponents. Calling the wall "medieval" was misleading, wrote Matthew Gabriele, of Virginia Tech, in The Washington Post, "because walls in the actual European Middle Ages simply did not work the way Trump apparently thinks they did." On CNN.com, David M. Perry, of the University of Minnesota-Twin Cities, insisted that "walls are not medieval." And in Vox, Eric Weiskott, of Boston College, urged readers to "take it from a professor of medieval literature: calling things you don’t like ‘medieval’ is inaccurate and unhelpful."

Readers who doubted that the moment demanded a defense of the Middle Ages could be forgiven. In a political battle of such high human stakes, the question of whether calling Trump’s proposal "medieval" constituted "an insult to the Middle Ages" (as the Voxheadline put it) might seem worryingly beside the point. But the wave of furious responses was entirely predictable. In their parochial, self-serious literalism, they exemplify a style that increasingly pervades public writing by humanities scholars — a style that takes expertise to be authoritative and wields historical facts, however trivial or debatable, as dispositive answers to political questions. Such literalism is bad rhetoric, a way of dissolving argument into trivia. It’s also bad history: At root, it betrays the humanities’ own hard-won explanations of how we have come to know the past.