Political scientists like me have wrestled over and over with how best to explain the Donald Trump phenomenon. It has been a social science gift: something unusual and very unexpected. Something to be analyzed and explained!

But the crisis that has emerged has also startled us. Trump is our black swan. No previous presidential candidate in American political history has been a dangerous demagogue, clearly unfit and unprepared for the office.

No one before in American presidential electoral history has been so narcissistically disdainful of the basic ethical requirements of democratic electioneering.

True, Trump’s campaigning is inept. He is full of B.S. – in the philosopher Harry Frankfurt’s sense of brazen, sociopathic indifference to truth. He is a weak, sometimes clownish demagogue, ferried in and out of Manhattan on a personal jet to his rallies here and there. He would be far more frightening if he had built a dense, numerous, and militant insurgency.

But think about it. He has threatened his opponent’s life, said that if he is President he will try to prosecute her and jail her, asked a foreign power and dangerous adversary to intervene in the election on his behalf, encouraged violence at his rallies, urged a massive assault on the civil liberties of a group of Americans, offended an historic ally and neighbor, the Republic of Mexico, in the most unhinged way, threatened to rip up stable treaty alliances that protect our security, lied constantly about policy questions of fact, engaged in smears and conspiracy thinking, flirted with anti-Semites and white nationalists, suggested that he will encourage nuclear proliferation if he is President, and he has urged his base to treat his electoral defeat, if it happens, as a case of illegitimate and rigged defeat.

Yet this rhetorical barrage has been effectively normalized. We have gotten all too used to this kind of menacing, deranged talk. The basic reason for that is his own party. It has refused to disown him. There is no line that he cannot cross. The Republican cohabitation with Trump is understandable. It’s not admirable, but it has a clear organizational logic. Given the enormous gains that Republicans made in 2010 and 2014, in Congress and among the states, they have a lot to protect. Most of the party’s office-holders have obviously decided that they must live with Trump and ride out the election to wherever it may lead. That has given him a license to say things that should have cost him his campaign long ago.

I think that he is going to lose the election – but I also think that more and possibly very damaging mischief is possible. There is still plenty of fuel for Trump to run on. He is making some of it by working on a “softening” that makes him appear ever so slightly thoughtful and judicious. Although the public recognizes how dangerous Trump is he nonetheless retains the support of a hefty slic of the likely electorate. Many Americans think that it is simply time for a change in leadership, even if that change would be unpredictable, to say the least. Just as the GOP’s defensive embrace of Trump has a logic to it, so too the resistance to a third Democratic term is understandable. People get tired of the same party being in charge of the presidency and think it’s time for their party to take the helm.

So there is a real danger about what happens at the end. If Clinton wins then Trump may seek to somehow trash her victory ― refuse to concede, deny the results, or both.

So here is my suggestion. The moderators of the first presidential debate, scheduled for September 26th, should ask both Hillary Clinton and Donald Trump the following simple question.

If you lose, do you commit to telephoning your opponent and to publicly congratulating him ― or her – on winning the election fair and square?

One way to get the moderators to ask this question is through social media. The hashtag here is #FirstDebateDemocracy. Use it to get the question out there.

Again, if you lose, do you commit to telephoning your opponent and to publicly congratulating him ― or her – on winning the election fair and square?

If the burden of making that phone call in the end falls to Trump we may see him evade the responsibility. At the debates we may see him shirk the task of agreeing to establish trust and comity across the partisan divide ― even when he is on the spot, accountable to a vast national audience.

But this question has to be put. It would be a step toward curing the damage that Trump has done to our democratic norms.

There are of course other questions for the first debate – and the subsequent debates. How do we make voting inclusive, not a struggle? How do we start to reduce polarization in Washington? How can we expand policies that we know have worked well, such as Social Security and the Affordable Care Act?

But one immediate obligation is the health of this election ― and of the decent customs that have been part of presidential elections. The moderators of the presidential debates should be thinking now, as they prepare for September 26th, about how they can help with that urgent task.