US election: Will normal rules ultimately apply?
Voters everywhere are in a mutinous mood. They seem hell-bent on defying conventional wisdom and making a mockery of orthodox punditry. They do not want to be bound by customary rules or behavioural norms.
That rebellious spirit has been glaringly evident during this American election season. It is seen most obviously in the rise of Donald Trump, the failure of establishment conservatives like Jeb Bush and Marco Rubio, the time it has taken Hillary Clinton to close the deal, and the unexpectedly strong showing of her rival, Bernie Sanders, who won in Indiana this week.
In Britain, it is demonstrated in the emergence of Jeremy Corbyn and even that online poll to decide upon a name for a new polar research ship, which ended up with a landslide victory for Boaty McBoatface.
Break-the-rules politics seems to be the order of the day. Voters seem determined to make the politically impossible become real. But normal and longstanding rules will most probably decide the outcome of the US presidential election and who ends up in the White House.
The black vote
The race for the Democratic presidential nomination offers a case in point. Nobody predicted that Bernie Sanders would win 18 contests and still be in the race by the time that baseball umpires started shouting, "Play Ball!"
However, he could not overturn the iron rule of progressive politics in America: you cannot win the Democratic presidential nomination without winning the African-American vote.
Hillary Clinton found that in 2008, when Barack Obama beat her. Bernie Sanders maybe sensed this in South Carolina, a vital early contest, where Mrs Clinton won 86% of the black vote.
Indeed, the only time during the primary season when she looked truly vulnerable came after her defeat in Michigan, where black support dipped to 68%. The following week, however, in Ohio, North Carolina, Illinois and Florida, she scored decisive victories because of the overwhelming backing of African-Americans.
Any hope that Mr Sanders had of overhauling her delegate lead ended that night. Black support held firm, and carried her to the brink of the nomination.
The female vote
For all the commentary that has been written about Donald Trump defying the usual laws of political gravity - it's become the recurring cliche of the campaign - he may ultimately be brought back down to earth by another ironclad rule.
It is impossible to win the presidency if you perform disastrously among women voters. No candidate in modern times has reached the White House without winning at least 43% of the female vote.
The women's vote is vital. In every presidential election since 1964, more women have voted than men. The female turnout rate has also been higher in every election since 1980 - four years ago, 63.7% of women voted compared to 59.8% of men.
In the last six elections women have voted Democrat - Barack Obama won 56% of the female vote - and it has given the party a huge demographic advantage. (For the trivia hounds out there, George Herbert Walker Bush was the last Republican to get 50% of the female vote.)
Now that he has essentially secured the Republican presidential nomination, Donald Trump's unpopularity among women should prevent him from winning the presidency itself. A recent CNN/ORC poll suggested that 73% of women have a negative view of him.
When asked how they would vote in a hypothetical head-to-head, 60% said they would support Hillary Clinton, while just 33% backed the billionaire. That figure would be significantly worse even than Bob Dole in 1996, who won only 38% of the female vote, and George HW Bush in 1992, who won 37% in a three-candidate contest involving Bill Clinton and Ross Perot.
Mr Trump's success is not a male-only phenomenon. In the primaries so far, the gender gap in his support is narrower than one might suppose - his support among men outstrips his support among women by 7 percentage points.
But his female problem has not been such a big obstacle in Republican primaries, because women make up a minority of voters. That will not be true in the November election, when between 52% and 54% voters will be women.
In what many female critics will doubtless regard as poetic justice, Donald Trump's sexism and misogyny should bar him from the White House and help elect the country's first female president.
Tim Miller, a former Jeb Bush adviser who has been prominent in the Stop Trump campaign, put it pithily to CNN: "The only way Trump is going to win the general election is if he manages to repeal women's suffrage between now and November." It is safe to say that is not going to happen.
The Latino vote
Just as the old rules are weighted against Donald Trump, so are the new. It is becoming increasingly difficult to win the presidency if you perform poorly with the Latino vote. Mitt Romney won 59% of the white vote in 2012, which would have won him the presidency in days gone by. But Hispanics and Latinos now make up 17% of the population, and Mr Romney won a dismal 24% share.
Given Donald Trump's signature remarks about Mexican immigrants being criminals and rapists, it is hard to see him improving on that. And it is not just states like California, Arizona, Nevada and New Mexico where the Latino population could be decisive.
In New York, 18% of the population is Latino or Hispanic. In Colorado, it is 20%, while in Florida it is 23%. Even in Connecticut, which we often mistakenly think of as a "white bread state", it is 14.2%.
Angry white men remain an important demographic, but there aren't enough of them to carry a candidate to victory.
As well as demographic factors, the Democrats benefit from what's called the "blue wall" - the states that repeatedly vote Democrat. There are 18 states, plus the District of Columbia, which have voted Democrat in the past six elections. They provide 242 of the 270 electoral college votes to win the presidency. This blue wall can be overcome, as George W Bush demonstrated in 2000 and 2004, but it means that Republicans have a narrow path to victory.
Donald Trump believes he can turn blue states like Pennsylvania and New York red, that he can upend all the rules. He did that to all but secure the Republican presidential nomination, one of the most extraordinary feats in modern-day American politics. Breaking the rules of general elections will be far more difficult.