By MAX FISHER and AMANDA TAUB
Yet for all the boos they elicit from experts, they draw frequent cheers at his rallies.
Scholars of American politics say this is because Mr. Trump, the Republican presidential nominee, is using international issues as a medium to connect with voters’ gut-level fears and desires, an approach that works precisely because his foreign agenda falls far outside the mainstream.
As Mr. Trump and his Democratic opponent, Hillary Clinton, meet on Wednesday for their final debate, in which foreign policy is slated to be a main topic, a look at his wholesale reframing of this set of issues reveals much about Mr. Trump’s improbable rise.
Studies show that most voters rank foreign issues low on their list of concerns, but they do listen and use those issues as a window through which they judge candidates’ values and ideology.
Mr. Trump has exploited this dynamic, offering ideas that experts consider unworkable, but that tap into some voters’ desire for a strong-handed leader. Foreign policy, some research suggests, provided an ideal medium for this message.
Typically, candidates cannot reach the national stage without first proving their fitness to certain institutions that care deeply about foreign policy: the news media that vets them, the parties that provide them with crucial support, the policy makers they will need once in office.
Because foreign policy is so complex and most voters do not follow its particulars as closely as they do domestic issues, those institutions play an outsize role in shaping the bounds of acceptable debate.
But Mr. Trump, a celebrity who largely self-financed his primary campaign, was able to bypass this process, hacking the politics of foreign policy to his considerable advantage — and in ways that could outlast his candidacy.
A foreign policy not about foreign policy.
In a perfect world, each voter would dedicate months of study to the complexities of major global conflicts, evaluate the available options, then determine which candidate’s plan best balances risks and rewards.
In the world we live in, voters choose whom to believe based on whose message feels truest.
“We have overwhelming evidence that voters don’t know that much about the details of foreign policy,” explained Elizabeth N. Saunders, a George Washington University political scientist.
“People tend to choose the candidate they like first,” and then take on that candidate’s views as their own, she added. “This is the way people make sense of a complicated world.”
All candidates wrap their policy agendas in simpler values, such as strength or inclusiveness, or stories of heroes and villains, Professor Saunders said, “as a way of crafting a narrative that voters who don’t follow the details can grab on to.”
That is especially true for foreign policy, she said, because it is so complex.
Mr. Trump seems to have reversed this process, beginning with the narrative and values he wishes to convey, then designing policies to maximize his message’s effect.
Because foreign policy requires difficult trade-offs, conventional candidates are limited in how emotionally appealing they can make their plans while keeping them workable. They also need to appease the hard-nosed policy experts or party officials those candidates rely on to get elected — and, eventually, to govern. But Mr. Trump was under no such constraints.
The result: Mr. Trump’s foreign policy is not a foreign policy at all, but rather a vessel for reaching voters on a purely ideological level.
The world according to Trump.
This explains how Mr. Trump has won support with, for example, threats to leave the North Atlantic Treaty Organization, though voters have expressed little interest in renegotiating the alliance and foreign policy professionals have warned it would risk disaster.
Paul Musgrave, a political science professor at the University of Massachusetts, summed up Mr. Trump’s message: “NATO requires cooperation. Cooperation is something you do if you’re weak. If you’re strong, people go along with you.”
As policy, that is dubious. But it is a powerful way for Mr. Trump to present himself as someone who will treat outsiders with suspicion and ruthlessly pursue economic gains. It is a message wrapped in foreign policy but meant to tap into more domestic concerns.
Colin Dueck, a George Mason University professor, wrote in a recent paper that Mr. Trump’s worldview demands and offers “a sort of Fortress America, or perhaps a gigantic gated community, separated from transnational dangers of all kinds by a series of walls.”
To voters “feeling displaced by long-term trends toward cultural and economic globalization,” Professor Dueck wrote, Mr. Trump’s policies promise “security, separation, and reassertion of control.”
During the Republican primaries, for example, Mr. Trump alarmed those outside his rapidly growing base with proposals to kill the families of terrorists and with praise for President Vladimir V. Putin of Russia, as well as for China’s 1989 crackdown in Tiananmen Square.
But for supporters, these and other statements suggested Mr. Trump could be trusted to impose order on the chaos they see in a rapidly changing world.
Because American voters have long approached international issues as a way to judge presidential candidates’ values, they are willing to overlook the particulars; foreign policy became a powerful medium for Mr. Trump and his supporters to connect.
When Mr. Trump warns that the United States is getting swindled by the Iran nuclear deal or the North American Free Trade Agreement, he is speaking directly to a feeling among many Americans that they have been sold out by untrustworthy elites, that the game is rigged against them.
And when Mr. Trump promises to force Mexico to pay for a giant border wall or warns that Iranian boats will be “shot out of the water” if their sailors “make gestures” at American sailors, he is communicating that he understands that his supporters feel fearful and humiliated, and that he will punish those responsible.
This message turned out to resonate with a surprisingly large audience — but where did this seemingly new constituency come from?
Research published this spring by a group of social scientists, led by Brian C. Rathbun of the University of Southern California, suggests an answer: Mr. Trump has tapped into what scholars call conservation values.
People who hold those values prioritize security, conformity and tradition. They also tend to fear physical threats and people they see as outsiders, whether that means foreigners or those of different races or religions. And they often express those values as a particular set of “hawkish” foreign policy views.
That hawkishness is very different from that of neoconservatives like President George W. Bush or interventionist Democrats like Mrs. Clinton. It is characterized by a desire to shut out the world, ruthlessly promote American interests, reject cooperation and meet threats with overwhelming force.
The paper, though written before Mr. Trump’s rise, details the worldview he would come to champion in surprising detail.
The distrust of cooperation shows up in Mr. Trump’s call to stymie alliances from Europe to Asia. The instinct to impose order by force appears in his proposals for unchecked violence against the Islamic State. And the “America first” nationalism can be seen in his demand that the United States seize Iraq’s oil.
Voters who hold conservation values are drawn to such policies not out of a sudden interest in global affairs, but as a way to express their fear of change and desire for order at home, the researchers found. They desire a strong leader who will protect “us” against an ever-more-menacing “them.”
Mr. Trump, by redirecting voters’ anxiety about demographic, cultural and economic changes toward foreign policy, gives his supporters a clearer set of villains — and a promise to do whatever it will take to defeat them.
Supporters do not primarily hear a policy agenda, but a promise: that Mr. Trump understands their fears and will protect them.
Mr. Trump may never have a chance to test the experts’ contention that his foreign policy proposals are unworkable. But the constituency he has surfaced and focused those policies on could demand them from future candidates, risking a repeat of this year’s campaign dynamic pitting the party establishment against its base.
Professor Saunders of George Washington pointed out that Republican leaders and Republican voters have diverged on foreign policy since Mr. Bush’s 2003 invasion of Iraq.
Mr. Trump’s legacy, she said, may be to widen those gaps.