Whenever I think about the dysfunctional horror of the looming presidential election in America – so weird that Nigel Farage can pop up in Mississippi on the Trump campaign – I can’t get Susan Sarandon or Plato out of my mind. Let’s talk first about the actor. When did Plato make a decent movie, eh?

A few weeks ago Sarandon gave a magazine interview to an overawed writer in which she set out her well-known political stall as a radical feminist who backed Bernie Sanders and doesn’t think much of Hillary Clinton. “There’s nothing about her I find feminist except that she’s a woman,” she said.

That betrays a casual, right-on ignorance of Clinton’s record over many decades, but never mind, Sarandon’s distaste is shared by many educated American women. “She’s a hawk, she’ll probably get us into another war,” etc etc, all good Islington-to-Santa Monica stuff. What was startling to me was that yet again Sarandon declined to say she’d vote for Clinton in November.

“I go by issues, I don’t vote with my vagina,” Sarandon tells audiences. She did it again in Australia the other day. She’s even hinted that she might vote Trump on the grounds that his election “will bring the revolution immediately”. How flakey is that?

All right, she’s only an actor, they get paid to read other people’s lines. But even though Bernie Sanders himself has finally backed Clinton with grumpy ill-grace, I keep hearing Americans – particularly younger, educated women – saying similar things: that they’ll vote Trump against the “Washington elite” or just abstain.

The Observer’s Nick Cohen recently wrote a belter of a column mocking leading American Republicans who keep busts of Churchill on their desks as a symbol of defiant courage but don’t have the guts to denounce and disown Trump, who has captured the ugly, angry party they spent decades creating for short-term gain.

That’s not quite fair on many Republicans. The Bush family and some other notables are standing aloof. Other figures have publicly stated – at political or personal risk to themselves – that they will vote for Clinton rather than for a man whose dangerous and volatile unsuitability makes him a threat to constitutional government.

There is a pretty disheartening list of rebels and appeasers. At the party convention, Trump’s beaten rival, Senator Ted Cruz, was booed for telling people to “vote your conscience”. Since he’s called Trump “a pathological liar, utterly amoral, a narcissist … and a serial philanderer,” we can take him as a no.

That makes Cruz and rejectionist Republicans better Americans than Susan Sarandon. Her arrogant emphasis on what matters to Susan seems – so far – to obscure her view of the bigger political picture, possibly to link her more closely than she might wish to the “Trump the Selfie” mood that is drawing millions of resentful Americans into a dark and angry narcissism.

Which brings me to Plato. Concerned friends in the US sent me some extracts from a newly published book, A Clear and Present Danger: Narcissism in the Era of Donald Trump – essays by prominent writers, academics and doctors on the polarising disorder they see sweeping their own country – while noting, as both Trump and Farage have done, that Britain’s Brexit vote serves to remind us that the revolt against elites and globalisation exists in Europe too.

A lot of this stuff has been around for decades. As a student 50 years ago I read the American historian Richard Hofstadter’s essay The Paranoid Style of American Politics, in which anti-foreigner nativism could easily be harnessed against newcomers, outsiders, black people, capitalism, Jews, the usual suspects. The leftwing social critic Christopher Lasch published The Culture of Narcissism as a consequence of post-war consumer capitalism as long ago as 1979. In Willie Loman, Arthur Miller’s Death of a Salesman created a Trump voter in 1949.

Lasch and Miller lived long enough to experience the Reagan presidency, its negative impacts softened by the incumbent’s relaxed and sunny disposition. The prospect of a Trump victory against Clinton – always a vulnerable candidate in my book – would seriously have frightened, though possibly not surprised, them. It’s been a long time coming and the Reagan/Goldwater wing of the Republican party has made the bouffant-haired Frankenstein possible.

Ted Cruz is not alone in identifying Trump’s very obvious self-absorption, the quality so grotesque it rendered him almost a stealth candidate until too late. What no one understood at first was how much his excesses would appeal to voters – not all of them poor white people whose jobs, prospects and traditions have been attacked or destroyed – who feel marginalised or threatened.

It’s part-cultural, part-economic, but it thrives in the celebrity culture we now inhabit, vastly enhanced by 24/7 social media. As harsh reality becomes more unpleasant, the temptation is to blur the edges between reality and illusion, to retreat into a magic world and the cult of self. Facebook, Google and YouTube make it ever more possible. Even the TV networks are making money out of Trump.

Of course, Plato didn’t do Twitter or have a presence on Facebook. But Andrew Sullivan, the British expat writer in the US, wrote a piece reminding New York magazine’s readers how the great man had warned that “tyranny is probably established out of no other regime than democracy,” in terms that describe the Trump scenario very well.

Plato was no friend of democracy (as pandering classics professors routinely fail to tell us in their TV series on Greek democracy), not least because it killed his hero Socrates. He saw it as a system that gradually expanded freedom and equality to the point where authority imploded and its ensuing disorders allow a demagogue to seize power, promising to “take back control” or “get our country back”.

Being of the elite himself, Plato explained, but with a populist touch, the emerging tyrant forces the now defenceless elite to compromise, flee or face retribution. Sound familiar? It certainly does. Watch those wobbling Republican millionaires shaking behind their locked gates. In an age that has delivered painful inequality in most advanced societies (unadvanced ones always have it), anger against elite wealth is very real and understandable. Which of us would not see more bankers jailed?

Yet Trump supporters seem even more blind to his faults than Susan Sarandon or Nigel Farage. Trump still hasn’t published his tax return, as all candidates have done for 40 years, and evidence emerges daily of strange financial ties/debts to Russian and Chinese interests.

The distinction between fact and fantasy is fast eroding. Trump is behind in most polls and may be rightly thrashed in November, a fading nightmare by Christmas. He may just “do a Brexit” and win. Does Farage get any of this, do you suppose? As a Poundland Trump, Farage tapped into suppressed resentment over “politically incorrect” feelings, but never provided any answers beyond that magic word: Brexit.

Yet on Wednesday night in Mississippi we saw a man whose creed is self-governing “sovereign” states interfering in another country’s sovereignty (he complained when Obama did it in the referendum), not against a candidate whose toxic rage so clearly threatens us all, but on his side. I wish I could say Susan Sarandon showed a better grip on reality. There’s still time.