Pauline Hanson said two remarkable things this week. No, not the customary Muslim-hating. That's entirely routine. It's written into the One Nation policy platform.
Truly remarkable was her admission that she might have been wrong about facts. And her withdrawal, or at least a partial withdrawal. And her apology.
Why is it remarkable? Because that's not what nationalist populist politicians like Hanson do. They may make outrageous statements, they may ignore reality, they may flat-out lie. But they don't admit to being factually wrong.
When Hanson's role model, Donald Trump, has been caught speaking an untruth, he never admits it, never withdraws it, never apologises for it.
When the US news outfit Politico conducted a fact-check on a week's worth of Donald Trump campaign speeches and interviews, it famously found that he uttered a mischaracterisation, exaggeration or falsehood every five minutes on average.
When caught lying red-handed, Trump resorts to weasel words and blame-shifts. Like his all-purpose classic: "All I know is what's on the internet."
Of course, "post-truth" politics were ushered in not by the populists but by the mainstream. Politico's equivalent fact-check on Hillary Clinton spotted a lie every 12 minutes, for instance.
Emeritus professor of political science at Monash University, James Walter, points to Tony Blair's position on the 2003 invasion of Iraq. Confronted with all the evidence warning of a disastrous blunder, the British prime minister simply asserted that "this is what I believe".
Says Walter: "Leaders felt it sufficient justification to say 'I say this because I believe it'. It's when people in the mainstream of politics start to say 'my belief is my justification' that seems to lead to all sorts of nutters saying it.
"It's this point about expertise not being believed. For instance, the idea that 'my view on climate change is as good as anyone else's'."
The populists merely took the opening offered to them by the mainstream. So that's why it was remarkable that when Pauline Hanson collided with facts and expertise this week, she eventually backed off. She gave support to the anti-vaccination movement, saying that vaccination could lead to autism, that she'd "think twice" before getting her own kids vaccinated these days, and encouraging parents to do their own research. She said that though she was not an expert, "more common sense" was needed on the topic. Parents should get their kids tested before deciding.
When challenged, her defence was: It's my "personal opinion". So far, this is the standard recourse of the populist.
But after four days of sustained criticism from the medical profession and the mainstream parties, she backed off. "I have heard a couple of doctors have said that there is no test. If that be the case, I am wrong. Vaccinations have controlled a lot of diseases. I admit that. As far as having tests done, I admit I was wrong with that."
James Walter describes this as "an unexpected concession from her – it's just so out of character". A Fairfax Media library search of the Hanson archive turned up only one other apology, or qualified apology. It was 20 years ago. She said she was "sorry" for terrible things done to Aboriginal people in the past but "I resent being made to feel guilty for something I did not do".
This is not an apology so much as an expression of sadness. She certainly didn't admit to any factual error.
An Australian political scientist who follows the populist movement worldwide, Robin Archer of the London School of Economics, agreed that this was out of character: "Hostility to experts is a feature of these movements worldwide."
And Donald Trump, Hanson's political and policy guru, has not backed off or apologised for his own anti-vaxx scepticism. On the contrary, he's asked a leading anti-vaccination activist, Robert Kennedy Jnr, to chair a commission into "vaccine safety" to ramp up the issue.
So what's happened? Hanson seems to have bumped up against a limit to "post-truth" politics. Have facts and experts triumphed over the fatuous equivalence of ignorance and knowledge? Are Australians perhaps less vulnerable to being gulled by exuberant populist denialism?
Archer says that it depends: "The traction the populists get depends on which experts are up for grabs. In the Brexit debate, professional economists were successfully traduced and intellectuals generally were successfully traduced. But the expertise of doctors is almost never mentioned in these debates.
"Hanson has made a mistake – it's not common sense to say that doctors are up the wrong alley, because everyone depends on their doctors for their personal health." Economists are fair game; doctors need more careful handling.
So Hanson has challenged the wrong category of experts, it seems. There is another critical factor in understanding her uncharacteristic backdown. She has been campaigning for her candidates in the West Australian election to be held this Saturday.
One Nation's polling was sagging. The media storm over her anti-vaxx comments smothered everything else she wanted to say in the final stage. It showed no sign of relenting. So as a pragmatic matter of political management, she needed to cut her losses. This is very conventional politics indeed.
It may be that Australians are less vulnerable to populist chicanery than some other nationalities, but this episode is not evidence for that proposition.
The second remarkable thing Hanson did this week was to admire Vladimir Putin. In one way, it's not remarkable at all. Trump's adulation of Putin is one of peculiarities of his presidency. And it's one of the common elements in the nationalist populist movement worldwide.
"There's Trump, but there's also Marine Le Pen in France who speaks sympathetically about Putin, Viktor Oban in Hungary speaks sympathetically about Putin," Archer says.
The hero worship of Putin even extends to the Vatican. A common factor among the Vatican's cliques of right-wing cardinals who oppose Pope Francis is their "great appreciation" for Putin, according to Massimo Introvigne of the Centre for Studies on New Religions in Turin.
Pauline Hanson said that she had great respect for the Russian leader because he was a "strong man".
She told the ABC's Insiders TV show: "The man stands up for his country, for his people. He's a proud leader of his nation and he has the support of his people. I would dearly love to see one of our two leaders stand up and deliver a speech like he has done on the floor of his parliament. I wish some of our leaders here would have some of that backbone.
"Because that's what people want, to be proud that people are Australians, that those who come here will be Australians and integrate and assimilate into this country."
When asked for her feeling about the way some of Putin's critics have been treated in Russia, she laughed and replied: "What happens in Russia, I really don't care. It's all about here."
So if it's "all about here", what of the 38 Australians who died when Russian-backed rebels shot down a civilian airliner, MH17, over Ukraine? Hanson's sympathies went not to her innocent dead countrymen but to the Russian president. She defended Putin: "Did he push the button?"
Robin Archer remarks: "The fact that Hanson would speak sympathetically about Putin despite this Australian angle is really quite extraordinary." It's more than that. Hanson puts the interests of her political project ahead of the interests of the Australian people. Much as she did in supporting anti-vaccine scepticism. This is nauseating.
Hanson's identification with a brutal autocrat who murders his political opponents and invades his neighbours is where the nationalist populist movement veers out of all historical precedent.
"Racism and anti-immigration and all the rest of it," says Archer, "that has a long history in the US over two centuries, much as it does in Australia. The 19th century Labor party in Australia was a kind of populist party fixated with race.
"What's unique about Trump is not that he stands against a race but that he stands against institutions. It's not that he's racist, it's that he's authoritarian. Europe in the 1920s and 30s had a history of authoritarian leaders, but there is no precedent in the New World nations," such as the US, Australia, Canada and NZ.
Hanson claims to admire "strong man" leaders. But Putin is not a "strong man". He's an authoritarian. And her other hero, Trump, has authoritarian tendencies.
What's the appeal of the "strong man" leader? "There are things happening that are very complex," Walter says. "The strong leader is usually characterised by resistance to cognitive complexity. They look for closure. They say 'I know'. They have simple answers. They ignore complexity. And that gives them a particular appeal."
If Hanson is heading towards authoritarian solutions, it takes her out of the Australian tradition of xenophobic populist and puts her in a new realm of danger to Australian institutions and democracy. In the immediate term, the West Australian election this weekend will test whether her party still has political momentum. One Nation won 9.5 per cent of the vote in the WA election of 2001.
This week, two polls, a Galaxy poll and a Reachtel survey, measured One Nation's support in WA at 8 to 9 per cent, almost exactly its level of 16 years ago. Are Hanson's supporters there in bigger numbers, reluctant to confess their sympathies to polling companies, waiting to shock the political establishment with an unexpectedly huge vote? Or has she reached some sort of plateau?
Is she the voice of the silent majority, or just the voice of a dangerous nutter fringe? WA will give us a clue.
Peter Hartcher is political editor.