Then-presidential candidate Donald Trump at a campaign stop to give a national security speech aboard the World War II battleship USS Iowa on Sept. 15, 2015, in San Pedro, Calif. (Robyn Beck/Agence France-Presse via Getty Images)

What will President-elect Donald Trump’s foreign policy look like? During the campaign, he made numerous statements about immigration, terrorism and trade, but no one knows whether Trump’s more extreme pronouncements reflect his convictions.

There’s no previous voting record or policies to give a hint — and there are few clues about the president-elect’s foreign policy advisers. And, as many foreign policy experts who previously served in Republican administrations took the extraordinary step of denouncing his candidacy during the campaign, there are few obvious choices to lead this new foreign policy team — and give a suggestion of what foreign policy doctrines we can expect.

Yet when placed against the backdrop of decades of American foreign policy, two striking perspectives emerge — one familiar and the other unprecedented.

The familiar — American decline

Trump’s promise to “make America great again” presumes that it once was but no longer is, tapping into the long-standing concern with American decline. Ronald Reagan made this fear a central part of his foreign policy plank. He campaigned to restore America’s place in the world by ending the Vietnam syndrome, fixing an economy mired in stagflation and getting tough with the Soviet Union after the “capitulation” of detente. For his 1984 reelection bid, Reagan campaigned on the slogan that “it’s morning in America again.”

Like Trump, Reagan argued that America’s decline was self-inflicted. Yes, the Soviets had hoodwinked the naive Americans. And, yes, our trade partners and strategic allies had taken advantage of an overly generous and gullible United States.

But Reagan blamed Washington for this sad state of affairs — our leaders acted as if America was in decline and made defeatism a self-fulfilling prophecy. If you believe it is true and act as though it is true, then it will become true. Fortunately, according to Samuel Huntington, Reagan had the good sense to believe in the promise of American renewal and, subsequently, made it happen.

Although without Reagan’s charm or twinkle, Trump has also blamed American decline on Washington, accusing U.S. leaders of being weak, stupid, corrupt and ready to make awful deals for no apparent reason. Trump also faults a liberal international order, which the United States helped build, for benefiting others at the direct expense of U.S. citizens.

But the unfamiliar is unnerving

Trump’s vision of America in the world is all power and no purpose, distinguishing him from all recent American presidents. Reagan promised to not only end America’s decline but also to restore America’s greatness, defined by its ideals and readiness to defend and spread freedom. It would become, once again, a “shining city on the hill.”

There is no Trump corollary to Reagan’s “shining city on the hill,” and its absence is significant. All U.S. presidents since World War II have proclaimed that American ideals, and not just military and economic might, are what make America great. America’s greatness owes to its democracy, the rule of law, human rights, liberties and the presence of a civic culture that gives everyone an equal chance and judges people on the basis of their accomplishments and not on their race, gender, religion or national origins.

And by tying America’s global standing to its ideal, one president after another has insisted that U.S. foreign policy is more than crass self-interest, oil, money or global supremacy. It also is about the goodness of the American people and the stature of the U.S. experiment. Successful presidents, including Reagan, communicated this spirit to the American people.

In one of his most memorable speeches, his 1989 farewell address, Reagan said: “I’ve spoken of the shining city all my political life. … After 200 years, two centuries, she still stands strong and true to the granite ridge, and her glow has held no matter what storm. And she’s still a beacon, still a magnet for all who must have freedom, for all the pilgrims from all the lost places who are hurtling through the darkness, toward home.” Every president since Reagan, from George H.W. Bush to Barack Obama, has expressed similar sentiments.

The combination of power and purpose accounts for the U.S.’s “soft power” — the ability to persuade others to support U.S. interests because they believe that doing so is good for them and the right thing to do. America’s global leadership has lasted as long as it has not just because of power but also because the United States has a record, however mixed, of trying to bring peace, prosperity and freedom to the rest of the world. The United States, as its leaders like to say, is both the exceptional and the indispensable nation.

For realists, who see international relations as a power play, there is no surprise that a country would interpret its strength as providential. Those at the top almost always credit their good fortune to their goodness. But realism also warns that foreign policies that emphasize power without purpose also quickly lose their legitimacy and popularity.

Foreign policies and international orders without a modicum sense of legitimacy soon crumble and can be sustained only by force. My research shows that stable and enduring international orders require some degree of acceptance, an acceptance based not only on short-term gains but also on agreed-upon norms, ideals and vision of a better world.

What is Trump’s vision, anyway?

Trump, so far, seems to have broken with this deep-seated belief that U.S. foreign policy should be inspired by American values and ideals. Trump has said little about American values or how they should inform the country’s place in the world. Indeed, he often suggests that these ideals are a burden and inconvenience, preventing him from exercising power as he wants.

Trump has often openly mocked the international norms and law, declaring that he would ignore them. To combat our foreign enemies such as the Islamic State, he recommends that we freely use torture and kill the families of suspected terrorists — even though doing so would put the United States on the wrong side of the civilized world and the law, branding the country as a war criminal. Whereas previous presidents have pledged not to use nuclear weapons, Trump has said just the opposite.

There is no statement of support for human rights or freedom around the world — or those leaders who support democracy. Instead, Trump has exclaimed a fondness for some of the world’s most reviled authoritarian leaders. And in contrast to Reagan’s generous spirit concerning refugees and wanting America to be a beacon for those lost in the wilderness, Trump worries that shining such a light will only encourage the wrong people to crawl onto American shores. This is shaping up to be a foreign policy that is all id and no superego, precisely the kind of leader that the great realist thinker Hans Morgenthau believed would lead to an aggressive nationalism and be a danger to world peace.

Unlike all previous presidents, who firmly believed that the strength and influence of the United States came from its power and its principles, Trump’s vision is power without principles. What does this mean? It represents an unprecedented break with a traditional tenet of U.S. foreign policy. It means that the United States will lean more heavily on brute power to influence friends and rivals alike.

The United States should drive a harder bargain on economic agreements. There are good reasons to want better trade deals, but Trump’s definition of a successful transaction is only the deal that leaves the nation in an advantaged position. There are good reasons to want our allies to contribute more to the security bill, but he suggests that the United States treat its commitments as matters of convenience, and threatens to withdraw from strategic alliances that do not provide immediate gratification.

International orders based on naked self-interest, threats, force and expediency are not long for this world, potentially taking everyone down with them. The absence of any mention of U.S. ideals creates a vision of a U.S. foreign policy that resembles a predatory business — and without any pretense of corporate social responsibility.

What is American foreign policy without American ideals? If Trump’s campaign rhetoric carries over to his presidency, we are about to find out.

Michael Barnett is a professor of international affairs and political science at George Washington University. His most recent book is “The Star and the Stripes: A History of the Foreign Policies of American Jews” (Princeton University Press, 2016).