In 20th Century Women, the 2016 film by director Mike Mills set in California on the eve of the 1980s, the characters are a pot pourri of jaded hippies, introspective young punks and lost souls living in a boarding house. The mother, played by Annette Bening, thinks she is struggling in raising her 15 year-old son (who seems perfectly fine) and wants to expose him to guidance by young feminists who turn out to be more radical than she – a first wave feminist and single mother – anticipated.

A key signifying scene – look, get ready for the enterprising 1980s, nothing will ever be quite the same again – comes when the characters sit and watch the live screening of President Carter’s once famous “crisis of confidence” address to Americans, delivered on the 15th July 1979.

Watching 20th Century Women a few days ago, Carter’s words jolted me, and that has never happened before. They provided a poignant reminder of how American presidents good, bad and indifferent used to speak to their country and its citizens – politely, respectfully, inclusively, intelligently‎. It was a timely reminder too of that what was dying with John McCain, the Arizona Senator and hero of the Vietnam war. An entire way, a style and ethic, of doing American politics is disappearing or has already gone.

McCain ran for president twice and lost. Yet he – like Carter –  understood the importance of losing with grace and grasped the value of a political afterlife post-defeat. In this  McCain was motivated by loyalty to higher ideals and not just ego. He was all too human and therefore imperfect, obviously. In his twin disasters during his 2008 run – the pick of Sarah Palin as his running mate, and his panicky campaigning halt during the financial crisis when his young opponent Obama stayed cool as a cucumber – he revealed that judgment of the kind needed for a successful presidency was lacking. But what did he do on the two occasions when he lost? After 2008 and eight years earlier in the dirty race with George W. Bush for the Republican nomination, he forgave, adjusted, and got back to serving his country on defence and much else.

Carter – another decent man dignified in the life he chose in the aftermath of defeat – was on air on the US networks on Monday paying tribute to McCain across the aisle.

‎Back to that Carter speech in 1979 included in 20th Century Women. ‎That summer he was battling to save his hopeless presidency, and a televised address that was ostensibly about the energy crisis turned into a plea for America not to get lost in factionalism and to unite to improve the condition of the country before it was too late. This being Carter, the valid message was buried under boring passages stuck down in the weeds that showed he thought too often in relentlessly statist terms.

Still, the moral heart of the speech was powerful and is worth quoting.

“I want to speak to you first tonight,” said Carter, “about a subject even more serious than energy or inflation. I want to talk to you right now about a fundamental threat to American democracy. I do not mean our political and civil liberties. They will endure. And I do not refer to the outward strength of America, a nation that is at peace tonight everywhere in the world, with unmatched economic power and military might. The threat is nearly invisible in ordinary ways. It is a crisis of confidence. It is a crisis that strikes at the very heart and soul and spirit of our national will. We can see this crisis in the growing doubt about the meaning of our own lives and in the loss of a unity of purpose for our nation. The erosion of our confidence in the future is threatening to destroy the social and the political fabric of America.”

And then this – Carter on that evening in 1979 might be speaking about Trumpian America now.

“As you know,” said Carter, nearly forty years ago, “there is a growing disrespect for government and for churches and for schools, the news media, and other institutions. This is not a message of happiness or reassurance, but it is the truth and it is a warning. These changes did not happen overnight. They’ve come upon us gradually over the last generation, years that were filled with shocks and tragedy.”

In the film the speech finishes and Dorothea, the mother, says that it was kinda inspiring and beautiful.

The others, the more culturally attuned youngsters, can sense that Carter’s appeal does not fit the times and a change is coming to America. “That guy is so screwed,” says one of the characters of Carter.

And so he was. Eighteen months later Carter was defeated by Ronald Reagan, a leader with a gift for optimistic rhetoric who was keenly aware that government interference was not the route to increased economic dynamism.

In 1980, Carter received a sound thrashing from voters who wanted to put the years of failure and lack of confidence behind them. That year Reagan won more than 50 percent of the popular vote to Carter’s 41% and Reagan won 489 to 49 votes in the electoral college, taking 44 of the states. That result wasn’t even Reagan’s best result. Four years later he won 58% of the popular vote and his Democrat challenger Walter Mondale carried only one state and the District of Colombia.

Those emphatic results – epic and clear victories – kept popping into my mind whenever Donald Trump boasted in the months immediately after his most narrow of victories – by a quirk, in which only 39,000 or so votes in three states tipped it for him – that his had been the greatest of all victories in the history of everything, ever. How could he stand there and boast based on an obvious lie, in denial of all the historical facts, and so many of his supporters seemingly not care that the claim was a lie? How could anyone in high office have such a‎ deficit of style? Isn’t he embarrassed? Nope. He’s a New York property developer. He is shameless.‎ Lying is the family business.

Trump’s childlike behaviour in 2016 infuriated McCain to the extent that he clashed repeatedly with the President, who is – as of now – not going to McCain’s funeral. In death he is making the point that Trump is other, a rogue element, alien, an aberration.

The problem with that McCain position (which always appeals to journalists like me raised on the romance of the American presidency) is that even if it is true, and it is questionable because Trump is the latest manifestation of the deep tradition of American populism, tens of millions of Americans do not ‎buy the Establishment line and they have a point. That’s why they voted for Trump. Weirdly, considering Trump’s dynastic ambitions for his daugher, he was the instrument for a rejection of the Bush and Clinton dynasties and Washington cosiness.

‎This deep division (along anti-Establishment lines) in America is not without precedent but serious by peacetime standards. It is not going away, even once time removes Trump.

Conservatives usually get the blame for the width of the divide in American life, for empowering Sarah Palin, and for owning guns, and for botching the halting of Trump.

I think that’s way too one-sided. America’s whining liberal left extremists, and the aggressive cosmopolitanism of the intolerent liberals, deserve even more of the blame. Their militant agenda on campus is anti-free speech and rooted in aggressively hectoring in a fascistic manner those who refuse to follow orders on subjects such as transgenderism. Voters have eyes and television sets and smart phones.

They saw it in the run up to 2016. Their anger was born of a wider fear that they were being made fools of by supposed authority, the Establishment again. The campus culture war stories were a major theme on the nightly news throughout 2015 and 2016. Trump in all his technicolour ghastliness provided voters with a chance to say “enough.”

There are echoes in the UK, where the Tory vote is becoming more working class and the part of the electorate not on campus that went straight to work might wonder why the hell they should be bossed around by entitled activists with a politically correct agenda. Answer – they shouldn’t be.

But why is an America so bitterly divided against itself a  problem for the rest of us? It’s not a problem if you are in the Kremlin or are a member of the authoritarian ‎Chinese leadership. It’s a bonus for the enemies of liberty.

For those of us in Western Europe, or Canada, New Zealand, Australia and Japan, in democracies where there are people who care about freedom and democratic values, an America impossibly divided is an America distracted, unreliable and incapable of providing sufficient leadership when it matters.

Coming down the line soon is a Chinese state with a potential lead in Artificial Intelligence and territorial ambitions. Meanwhile, Russia ponders menacing the Baltic states, and bothering Sweden and Poland too, and killing its enemies on British soil. In the face of such defence and security risks and existential challenges, if you think Jean Claude Juncker and his pals in Brussels are the answer then you must have been smoking a particularly strong batch of that stuff the young stoners in 20th Century Women favoured.

No, the world is going to need a functioning, healthy America, maybe sooner than we realise. After isolationist, erratic Trump, we had better hope that there is someone remarkable out there with manners and grace in the lower reaches of American politics capable of marginalising the extremes and leading that country back to true greatness.