Editor's Note: (Yascha Mounk is a lecturer at Harvard University and a fellow at New America. He is the author of "Stranger in My Own Country: A Jewish Family in Modern Germany" and has written for CNN, The New York Times, The Wall Street Journal, Foreign Affairs and The Nation. The views expressed in this commentary are his.)
(CNN) Just days ago, hundreds of the most prominent political scientists in the United States -- most of whom usually stay far removed from the partisan fray of electoral politics -- did something extraordinary: They penned a public letter to express their deep concern about Donald Trump. "A Trump Presidency," they wrote, "would pose a grave threat to American democracy and to other democratic governments around the world."
I was one of the signatories to this letter. Since the election, Trump has moderated his tone. Today, the ordinary mechanisms of a peaceful transition of power are on full display, with Barack Obama welcoming his democratically elected successor into the White House. But, like many of my colleagues, I still believe that Trump's willingness throughout his campaign to break with the most basic democratic norms should be seen as a serious warning sign.
In a stable democracy, political leaders promise to abide by the outcome of the election. They recognize that their political opponents are legitimate. They respect the independence of the legal system. And they defend the right of the press to criticize office-holders.
Trump, by contrast, repeatedly implied that he would not accept the outcome of the election if Hilary Clinton had won. He has consistently promised to "lock her up." He has attacked the judiciary, claiming that Judge Gonzalez Curiel is biased because he is "Mexican." And he has incited the most violent hatred against members of the press, promising to open up libel laws if elected.
I fear for what might come next. As a candidate, Trump relished in destroying every norm of political tradition and decency, staking out an openly authoritarian pitch to his base -- and was rewarded with a handsome victory. So it is not too difficult to imagine that Trump might prove just as willing to act in shocking and yet unforeseeable ways once he assumes office.
Could he bully the media into silence or complicity? Could he order federal law enforcement agencies to disregard due process when they chase after black suspects, or police Muslim communities, or round up undocumented immigrants, or beat back mass protests? Could he order the military to target the families of terrorists? And could he ignore the protestations of the Supreme Court when it tries to overrule him?
Perhaps not. But we simply cannot know. And that's the scary part.
As political scientists, we are used to studying what is likely to happen, not what we might do to influence the outcome. And we tend to be interested in the structural factors that influence general regularities, not the ways in which individuals might help to sway a particular case. This is another habit we have to break now. For how the next four years will play out depends in important ways on the actions of real-life people, who can take the honorable or the dishonorable course of action, discover the best in themselves or go down in history as enablers of democracy's demise.
The person facing the most important decision is Donald Trump. However ugly a campaign he ran, he is now the President-elect of the United States. The anger he has harnessed is visceral and the power he holds immense. He can try to look beyond the easy and incendiary slogans of the past months, working hard to improve the lives of the millions who put their trust in him. Or he can continue to spout slogans, to look for easy scapegoats and to put his own interests above those of the country. What happens to this country -- and whether Trump will be remembered by future generations as an unlikely hero or an arch villain -- is chiefly up to him.
It is also up to the old guard of the Republican Party. For all of Trump's power, his ability to do damage to the republic could be held in check by the fact that many elected legislators from his own party retain a deep commitment to the Constitution, and have been deeply dismayed by many of his statements. If Trump gives in to his worst instincts, the fate of the republic may hinge on their ability to summon the courage they have so far lacked.
The media are crucial, too. During the campaign, they have oscillated between calling out Trump's lies and treating him as just another mainstream candidate. If Trump starts to violate the Constitution or to intimidate his critics, journalists of all political persuasions have to speak out against him with one voice -- lest attacks on free speech be normalized. Yes, they may come under pressure from the administration. And yes, they will lose many readers and viewers. But for journalists to normalize a President who tries to muzzle the press is to dig their own graves.
The most important agents, however, are all of us -- as citizens or parishioners, members of charities or country clubs, teachers or shareholders. As Hillary Clinton said, we owe Trump "a chance to lead." But we must also defend "the rule of law, the principle that we're all equal in rights and dignity, and the freedom of worship and expression." If Trump should decide to encroach on those, it is incumbent on all of us to resist him in any way we can: by taking to the streets, by refusing to carry out illegal orders, by risking our lives and livelihoods if that turns out to be the only way.
In the end, democracies are only as strong as their citizens' lived commitment to its basic principles. Trump may yet turn out to be an honorable President. But if he doesn't, the next years will afford us an opportunity -- unprecedented in this magnitude in the history of the American republic -- to demonstrate the depth of our commitment to the founding principles to which we so readily pay lip service. The fate of liberal democracy, from coast to coast and far beyond these shining shores, may depend on it.