“Should this book one day be published…” So began a dedication that, seventy-five years ago in Nazi-occupied France, the renowned French historian Marc Bloch inscribed in a small book he was then writing. As it turned out, the book — The Historian’s Craft — was published, but posthumously, and unfinished. Shortly after he wrote the dedication, Bloch joined the resistance. Captured in 1944, he was tortured and executed by the Nazis scarcely a week after the Allies landed at Normandy.

This somber anniversary falls at an awkward moment in our own history. This summer, a group calling itself Historians Against Trump published an “Open Letter to the American People.” The signatories, warning against the “exceptional challenges” that Donald Trump’s candidacy “poses to civil society,” cited their “professional obligation as historians to share an understanding of the past upon which a better future may be built.” Critics quickly pounced, most notably the literary theorist Stanley Fish who sought to deconstruct the historians’ claims. Not only did he slam the letter-writers’ hubris, but also chuckled over the letter’s claim that historians are uniquely placed to carry the lessons of the past into the present. The historians, having gussied up opinion as truth, had demonstrated once again “how little they understand the responsibilities and limits of their profession.”

The fires stoked by Fish’s column continue to burn, throwing a sharp light on the debate’s central question: What is the use of history? This question, with which Bloch begins his book — whose original title in French, tellingly, is In Defense of History — remains, today more than ever, the central question for those whose livelihood is the writing and teaching of history. Despite Fish’s effort to dismiss our relevance, historians occupy a special place in this election season. Though a deconstructionist would demur, this election season in particular reminds us, as the late Daniel Patrick Moynihan observed that we are entitled to our own opinions, but not to our own facts.

My students invariably ram home this distinction between facts and opinions. It bears, in part, on the questions they ask about the character of past events or individuals or the evolution of political institutions or cultural traditions. But the classroom’s importance in maintaining this distinction is also apparent not just in their questions, but also in their way of life. My kids step into class fully wired: hooked up to the postmodern equivalent of IV treatments, they all carry electronic devices in their hands and white buds in their ears. Their lives bathe in the sea of social media, and while I ask them to unplug once class begins, I cannot pretend to wring them dry of all they have absorbed. ...