Trump supporters are analyzed in two general streams: the economically left-behind vs. the culturally displaced. The first seeks explanations in stagnant wages, dying industries and offshoring. The second seeks explanations in the rise of non-whites and cultural wars over basic values. The two, of course, can overlap.

A third approach, however, focuses on the underlying psychology of liberals and conservatives. A recent study found that just four questions on child-rearing predict Trump voting. Those who favor strict upbringing and obedience are much more inclined to support Trump.

Longer, similar questionnaires predict the same. Basically, these researchers are reviving the pioneering 1947 study by Theodor Adorno, a refugee from the Nazis, and others of which personalities incline to authoritarianism. A series of 29 questions on likes and dislikes revealed rigid, conformist and hierarchical personality characteristics that formed an F-Scale (for fascist).

Published in 1950 as “The Authoritarian Personality,” it made a brief splash but faded. Psychological insights into the deep roots of political irrationality tend to suffer similar fates. Critics question their neo-Freudian assumptions and suspect biased framing of questions.

But I’m beginning to think there’s something to the approach. Surveying both the U.S. and most of Europe, it looks like some 15 percent or more of the population just hates the way things are. Most of the time, they are quiet, nursing their grudges. They may vote for a variety of parties and candidates, but many do not vote. Their anger is free-floating, with no political party to attach to. The rage is always there, usually underground, but lacks organizational outlets.

Then something happens — an economic downturn or wave of immigrants — that triggers angry individuals to express their resentment at their status and at minorities to form a rightist party. The Tea Party blossomed in early 2009, just after the financial meltdown and the inauguration of the first black president, a double whammy.

One solid recent finding: The strongest Trump supporters are white evangelical Protestants. Doubtless true, but it begs the question: Where was their political home before Trump? They’ve been heavily Republican for decades — televangelist Jerry Falwell mobilized them — but the Depression made many of them Democrats. And many were apolitical, trusting not in princes but in Jesus.

Some fear the recrudescence of fascism, as in former Secretary of State Madeleine Albright’s new book, “Fascism: A Warning,” on the dangerous precursors of authoritarianism. Current movements, here and in Europe, indeed share some of Mussolini’s and Hitler’s lines — extreme nationalism, economic autarchy, scapegoating of minorities.

A far-right party, the Alternative for Germany, has entered the Bundestag for the first time since World War II, the Dutch Freedom Party and the French National Front came in second last year, and a center right–far right alliance won the Italian election. Every European country has a far-right party that wins at least 15 percent.

Fascist movements such as the Spanish Falange, South African Ossewabrandwag and Vargas’s Brazilian New State (“fascism with sugar”) have vanished, but Hungary’s Jobbik, India’s RSS (a pillar of Modi’s Hindutva), the Ku Klux Klan and White Power militias have risen. The naked Nashville shooter proclaimed himself a “sovereign citizen,” a term used by some militias; his victims were black and Hispanic.

Political extremists typically form a violent core embedded among supporters and sympathizers. A hallmark of fascist movements are uniforms and military organization. The American Klan and militias wear uniforms but denounce federal power in favor of states’ rights, a remnant of the Confederate cause.

Mostly, however, we face “illiberal democracy,” CNN’s Fareed Zakaria’s term embraced by Hungarian Prime Minister Viktor Orbán. It means using democratic procedures to infringe rights and eliminate opposition. Populist manipulators fan primitive fears to stampede voters, as Putin has done in Russia. Orbán recently dog-whistled Hungarian-born American financier George Soros as a threat to Hungarian sovereignty.

Two recent books fear the erosion of democracy: “How Democracies Die” by Steven Levitsky and Daniel Ziblatt, and “The People vs. Democracy” by Yascha Mounk (all Harvard instructors). They see anti-democrats gradually impugning minorities, the media, judiciary, parties and reasoned discourse in favor of angry, intolerant populism.

Well, true enough, but also a nearly permanent undercurrent. Crusty realist Hans Morgenthau, another refugee from Nazi Germany, published “The Decline of Democratic Politics” in 1962, mostly essays from the 1950s, when McCarthyism seemed poised to take over American politics.

But American democracy is self-regenerative. Look at the recent demands of women to not be put down and school students to not be shot. Both are engaging in politics as never before, jolting the establishment. The biggest jolt would be if most 18- to 24-year-olds started voting.

New economic advisor Larry Kudlow — acting, self-importantly, as White House spokesman — suggested UN ambassador Nikki Haley was confused about new sanctions on Russia. Her crisp reply, “I don’t get confused,” rebuked both Kudlow and the president, electrified feminists and positioned her as a presidential possibility. I wish male Trump appointees were so bold, but most seem frightened.