A recession might be just around the corner, but for experts in the field of “authoritarian studies,” these are boom times. Jonathan Weiler, a political scientist at the University of North Carolina at Chapel Hill, has spent much of his career studying the appeal of authoritarian figures: politicians who preach xenophobia, beat up on the press and place themselves above the law while extolling “law and order” for everyone else. He is one of many scholars who believe that deep-seated psychological traits help explain voters’ attraction to such leaders. “These days,” he told me, “audiences are more receptive to the idea” than they used to be.

Could it be that millions of President Trump’s supporters are simply wired to see the world very differently from his critics? “In 2018, the sense of fear and panic — the disorientation about how people who are not like us could see the world the way they do — it’s so elemental,” Mr. Weiler said. “People understand how deeply divided we are, and they are looking for explanations that match the depth of that division.”

Recent social scientific research has paid special attention to the supposedly authoritarian personalities of many Republican voters. “Trump’s electoral strength — and his staying power — have been buoyed, above all, by Americans with authoritarian inclinations,” wrote Matthew MacWilliams, a political consultant who surveyed voters during the 2016 election. But what, exactly, is an “authoritarian” personality? How do you measure it?

Long before the rise of Mr. Trump — for more than half a century — social scientists have tried to figure out why some seemingly mild-mannered people gravitate toward a strongman. They have created methods to dig below economics, religion and other social factors in the hope of uncovering a set of more essential political instincts. Sometimes these efforts veer into dangerous reductionism, but nonetheless they’re probably on to something.

In the years after World War II, the philosopher (and German refugee) Theodor Adorno collaborated with social scientists at the University of California at Berkeley to investigate why ordinary people supported fascist, anti-Semitic ideology during the war. They used a questionnaire called the F-scale (F is for fascism) and follow-up interviews to analyze the “total personality” of the “potentially antidemocratic individual.” ...