In 1994, Newt Gingrich, brandishing his Contract with America, led a Republican revolution that swept aside Democratic majorities in the House and the Senate, initiating an epoch of conservative ascendancy that lingers on. Don Sipple, a Republican campaign consultant, declared at the time that the 1994 midterms pitted a Republican Party calling for “discipline” against a Democratic Party focused on “therapy.”

Two years later, George Lakoff, a professor of linguistics at Berkeley, published “Moral Politics: How Liberals and Conservatives Think,” which argued that

Deeply embedded in conservative and liberal politics are two different models of the family. Conservatism is based on a Strict Father model, while liberalism is centered on a Nurturant Parent model. These two models of the family give rise to different moral systems.

Several approaches to contemporary politics echo the insights of Sipple and Lakoff. The crucial word now, however, is authoritarianism.

The election of Donald Trump — built as it was on several long-term trends that converged in 2016 — has created an authoritarian moment. This somewhat surprising development is the subject of “Remaking Partisan Politics through Authoritarian Sorting,” a forthcoming book by the political scientists Christopher Federico, Stanley Feldman and Christopher Weber, who argue that

Three trends — polarization, media change, and the rise of what many people see as threats to the traditional social order — have contributed to a growing divide within American politics. It is a divide between those who place heavy value on social order and cohesion relative to those who value personal autonomy and independence.

The three authors use a long-established authoritarian scale — based on four survey questions about which childhood traits parents would like to see in their offspring — that asks voters to choose between independence or respect for their elders; curiosity or good manners; self-reliance or obedience; and being considerate or well-behaved. Those respondents who choose respect for elders, good manners, obedience and being well-behaved are rated more authoritarian.

The authors found that in 1992, 62 percent of white voters who ranked highest on the authoritarian scale supported George H.W. Bush. In 2016, 86 percent of the most authoritarian white voters backed Trump, an increase of 24 percentage points.

Federico, Feldman and Weber conclude that

Authoritarianism is now more deeply bound up with partisan identities. It has become part and parcel of Republican identity among non-Hispanic white Americans.

Last year, Federico, writing with Christopher Johnston of Duke and Howard G. Lavine of the University of Minnesota, published “Open versus Closed: Personality, Identity, and the Politics of Redistribution,” which also explores the concept of authoritarian voting.

In an email, Johnston summarized some of their findings:

Over the last few decades, party allegiances have become increasingly tied to a core dimension of personality we call “openness.” Citizens high in openness value independence, self-direction, and novelty, while those low in openness value social cohesion, certainty, and security. Individual differences in openness seem to underpin many social and cultural disputes, including debates over the value of racial, ethnic, and cultural diversity, law and order, and traditional values and social norms.

Johnston notes that personality traits like closed mindedness, along with aversion to change and discomfort with diversity, are linked to authoritarianism:

As these social and cultural conflicts have become a bigger part of our political debates, citizens have sorted into different parties based on personality, with citizens high in openness much more likely to be liberals and Democrats than those low in openness. This psychological sorting process does not line up perfectly with older partisan differences based on class, because those higher in income and education also tend to be higher in openness.

Johnston addresses class differences in voting patterns and also differences stemming from the level of a voter’s interest in politics:

An important caveat is that individuals who take a stronger interest in politics and know more about it are more likely to be sorted on the basis of openness. So, it’s really among those most “politically engaged” Democrats and Republicans where we see members of different parties diverge in openness. Moreover, sorting into different parties on the basis of openness appears to be much stronger among non-Hispanic whites than other racial and ethnic groups.

In their book, Johnston, Lavine and Federico reinforce this point:

With the rise of cultural and lifestyle politics, Democrats and Republicans are now sharply distinguished by a set of psychological dispositions related to experiential openness — a general dimension of personality tapping tolerance for threat and uncertainty in one’s environment.

The revived interest in authoritarianism in politics began well before anyone seriously considered the possibility of a Trump candidacy — except, apparently, Trump himself.

In 2009, Marc J. Hetherington of Vanderbilt and Jonathan D. Weiler of the University of North Carolina, wrote one of the fundamental texts on this topic, “Authoritarianism and Polarization in American Politics.”

In it, Hetherington and Weiler argue that

preferences about many of the new issues on the American political agenda, such as gay rights, the war in Iraq, the proper response to terrorism, and immigration are likely structured by authoritarianism.

There are “colliding conceptions of right and wrong,” they write, between those on the high and low ends of the authoritarian scale. That, in turn, makes it difficult “for one side of the political debate to understand (perhaps, in the extreme, even respect) how the other side thinks and feels.”

This October, Hetherington and Weiler will publish an elaboration on their argument, “Prius or Pickup? How the Answers to Four Simple Questions Explain America’s Great Divide.” They are abandoning the use of the word authoritarian because of its negative connotations and its association with fascism.

In an email to me, Hetherington said that in their book he and Weiler will describe “people on opposite sides of the divide as having a fixed or fluid worldview:”

Those with a fixed worldview tend to see “American Carnage,” while those with fluid worldviews see the world as a big, beautiful place that is safe to explore. The fixed tend to be wary of what they perceive as constant threats to their physical security specifically and of social change in general. The fluid are much more open to change and, indeed, see it as a strength. For them, anger lies in holding on to old ideas and rejecting diversity.

Hetherington and Weiler argue that the answers to questions about the four childhood traits reveal “how worldview guides a person in navigating the world,” as Hetherington put it in his email:

Not only do the answers to these questions explain preferences about race, immigration, sexual orientation, gender attitudes, the projection of military force, gun control, and just about every “culture war” issue, people’s worldviews also undergird people’s life choices. Because ‘the fixed’ are wary about the dangers around them, they prefer the country over the city. ‘The fluid’ prefer the reverse.

Political analysts have become more and more aware of how voters’ sense of themselves as liberals or conservatives, Democrats or Republicans, has taken on heightened importance. Affirming one’s political tribe or community has in many respects become more important in deciding whom to vote for than the stands candidates take on issues.

In a March paper, “Ideologues Without Issues,” Lilliana Mason, a political scientist at the University of Maryland, wrote:

The power behind the labels “liberal” and “conservative” to predict strong preferences for the ideological in-group is based largely in the social identification with those groups, not in the organization of attitudes associated with the labels. That is, even when we are discussing ideology — a presumably issue-based concept — we are not entirely discussing issues.

Mason continued:

Identity-based ideology can drive affective ideological polarization even when individuals are naïve about policy. The passion and prejudice with which we approach politics is driven not only by what we think, but also powerfully by who we think we are.

Matt Grossmann and Daniel Thaler of Michigan State University further expand on the role of psychological traits in voter decision-making in their forthcoming paper, “Mass-Elite Divides in Aversion to Social Change and Support for Donald Trump.” They found that aversion to change “is strongly predictive of support for Trump” among regular voters, but much less so among Republican political elites.

They measure aversion to change by the answers to two polling questions: “Our country is changing too fast, undermining traditional American values” and “By accepting diverse cultures and lifestyles, our country is steadily improving.”

The accompanying graphic shows how those who think that the country is changing too fast and who disagree with the notion that diverse cultures and lifestyles improve the United States voted decisively for Trump.

Leonie Huddy, a political scientist at Stony Brook, sent me her analysis of how political conflict has shifted from economic to psychological factors.

The groups that have come to define partisanship in recent years, she wrote,

are far more grounded in social and moral values, geographic choice, and identity politics than the influential groups of yesteryear (especially unions) that maintained a focus on group economic interests. African-Americans may be an exception, but there is even a trend among young blacks to move away from the Democratic Party because they see the party as insufficiently focused on police brutality and other issues.

The result, in her words, is a political environment in which

the new affinities that shape partisanship are more a matter of choice than something one is born into or passed on by parents. That gives partisanship a more fluid nature than in the past and opens it to the formation of affinities grounded in personality, values, religion, and lifestyle choices.

In her 2005 book, “The Authoritarian Dynamic,” Karen Stenner — a former member of the political science departments at Princeton and Duke and now a behavioral economist in Australia — described politics as a clash of conflicting personal beliefs or moral value systems.

Stenner demonstrated, first, that levels of authoritarianism rise and fall in proportion to the experience of “normative threat,” and second that over the past generation authoritarianism has been predictive of Republican voting.

universal theory about what causes intolerance of difference in general, which includes racism, political intolerance (e.g. restriction of free speech), moral intolerance (e.g. homophobia, supporting censorship, opposing abortion) and punitiveness. It demonstrates that all these seemingly disparate attitudes are principally caused by just two factors: individuals’ innate psychological predispositions to intolerance (“authoritarianism”) interacting with changing conditions of societal threat.

Looked at this way, recent developments experienced by many voters as alarming — including the financial collapse of 2008, the surge of third-world immigration in the United States and Europe and continuing fears among traditionalists that the social order is under assault — have fueled authoritarianism:

The threatening conditions, resonant particularly in the present political climate, that exacerbate authoritarian attitudes include at least the perception of civil dissent and unrest, loss of confidence in social institutions, unpopularity of leaders on both sides of politics, divisive presidential campaigns, internal or external crises that undermine national pride or confidence, national economic downturn and rapidly rising crime rates.

In an email, Stenner provided figures from a recent EuroPulse surveyshowing that authoritarianism is stronger in the United States than it is in the European Union: In the E.U., 33 percent of the electorate can be described as authoritarian, while in the United States, it’s 45 percent.

The animosity between authoritarians and non-authoritarians has helped establish what Johnston, Lavine and Federico describe as the “expressive dimension” of policy choices:

In this view, the influence of personality on economic opinion arises not because the expected outcomes of a policy match an individual’s traits, but because those traits resonate with the social meaning a policy has acquired.

They explain further:

Citizens care less about the outcomes a policy produces and more about the groups and symbols with which a policy is associated.

Mason enlarged on this argument in her 2015 paper, “‘I Disrespectfully Agree’: The Differential Effects of Partisan Sorting on Behavioral and Issue Polarization.” Her argument is a direct challenge to those who take, as she puts it,

an instrumental view of politics, in which people choose a party and decide how strongly to support it based solely on each party’s stated positions and whether the party shares interests with them.

Instead, she writes,

Contrary to an issue-focused view of political decision making and behavior, the results presented here suggest that political thought, behavior, and emotion are powerfully driven by political identities. The strength of a person’s identification with his or her party affects how biased, active, and angry that person is, even if that person’s issue positions are moderate.

While much of this research uses the “preferred traits in child-rearing” questions to measure authoritarianism, two sociologists at the University of Kansas, David Norman Smith and Eric Hanley, observe in “The Anger Games: Who Voted for Donald Trump in the 2016 Election, and Why?” that those questions do not capture the full scope of authoritarianism, especially the more aggressive authoritarianism that they believe drives voters to Trump.

Smith and Hanley used what they call a “domineering leader scale” to measure

the wish for a strong leader who will force others to submit. The premise is that evil is afoot; that money, the media and government authority — and even “politically correct” moral authority — have been usurped by undeserving interlopers. The desire for a domineering leader is the desire to see this evil crushed.

The domineering leader scale is based on responses to two statements: “Our country will be great if we honor the ways of our forefathers, do what the authorities tell us to do, and get rid of the ‘rotten apples’ who are ruining everything” and “What our country really needs is a strong, determined leader who will crush evil and take us back to our true path.”

If an aggressive, domineering authoritarianism is a prime motivator for many Trump supporters, as Smith and Hanley contend, the clash between Republicans and Democrats is likely to become more hostile and warlike.

Federico, Feldman and Weber note that

since the early 2000s, many especially acrimonious political debates have focused on threats to social stability and order — debates surrounding abortion, transgender rights, immigration, and the role of the federal government in protecting the rights of marginalized social groups.

The rising “salience of these debates,” they write, “has contributed to a growing ‘authoritarian divide’ within the United States, at least among White Americans.”

Trump has purposefully exacerbated the “many especially acrimonious political debates” now dominating public discourse, deepening not only the authoritarian divide, but the divide between open and closed mindedness, between acceptance and racial resentment, and between toleration of and aversion to change. He evidently believes that this is the best political strategy for presiding in the White House and winning re-election, but it is an extraordinarily destructive strategy for governing the country and for safeguarding America’s interests in the world.