While it's far from clear who will win next week's presidential election, four outcomes are within watermelon-seed-spitting distance from certain.

One, the margin of victory will be slim. Two, the media will see that as proof of the terrible and worsening polarization that afflicts American society. Three, there will be headlines like "a nation divided." And four, political scientists will shake their heads in amazement that a conclusion so wrong could be believed by so many intelligent people.

The views of the American public are neither volatile nor increasingly extreme. American society is not polarized.

In fact, the views of Americans in the aggregate are centrist. And remarkably stable. "The way that the public thinks about poverty, opportunity, business, unions, religion, civic duty, foreign affairs and many other subjects is, to a large extent, the same today as in 1987," noted the Pew Research Center in a June report on its American Values survey, which it has conducted for 25 years.

"The values that unified Americans 25 years ago remain areas of consensus today, while the values that evenly divide the nation remain split," Pew concluded. "On most of the questions asked in both 1987 and 2012, the number agreeing is within five percentage points of the number who agreed 25 years ago. And on almost none has the basic balance of opinion tipped from agree to disagree or vice versa."

There are only two exceptions: "views of government and social values."

On questions such as "do you agree that the government is really run for the benefit of all people?" the trend lines are volatile but they've mostly been falling for the past 10 years - getting grimmer, that is - and are now unusually low. For example, only about 35 per cent of Americans agree that "most elected officials care what people like me think." But that's not unprecedented. Responses were similar, or worse, in 1992 and 1993.

Unlike that mixed picture, the change in social values has been unequivocal. In 1987, over half of Americans agreed that school boards should have the right to fire homosexual teachers, almost half disagreed with the statement "it's all right for blacks and whites to date," and 30 per cent felt that "women should return to their traditional roles." Today, those numbers have fallen to roughly 20 per cent for the first two and 10 per cent for the last one.

So Americans are far more tolerant today: That's the one and only indisputable and unprecedented change in American values detected by Pew over the last 25 years.

And yet it is all but universally believed that the United States has divided and polarized. Why? Because people keep making some basic mistakes.

One is to assume that the views of the political class - politicians, party officials, activists, and pundits - mirror those of the American public. They don't. Parties have internal dynamics of their own, as does the broader political class, and they can become quite detached from popular views: Think about all the volatility within the political class over the last 25 years and then recall the stability within the American public.

Another mistake is assuming that election results faithfully reflect what the electorate wants. Parties choose candidates. Only then do voters get to choose between candidates. If Americans were forced to choose between a Hummer and a Prius, they would choose a Hummer or a Prius, but that wouldn't mean that a Hummer or a Prius is what they really want.

A third mistake is particularly critical. People assume that "evenly divided" is the same as "deeply divided," complains Morris Fiorina, an esteemed political scientist at Stanford University. That's ridiculous. "Just because the race is almost tied says nothing at all about polarization. If every voter were completely indifferent between the candidates and flipped a coin in the voting booth, the results would be a 50: 50 tie but it wouldn't indicate polarization."

In his 2005 book, Culture War? The Myth of a Polarized America, Fiorina illustrated the point with two simple graphs. One showed a "U" with a vertical cut-off in the middle. This is an electorate that is evenly divided and extremely polarized - an electorate where most people can be found at the extremes of the left and right.

When people treat "closely divided" as if it's the same as "deeply divided," this is what they assume the American electorate looks like.

But in a second chart, Fiorina flipped the "U" upside down to portray an evenly divided electorate in which most people cluster around the centre. Commentators seldom even consider that configuration. But as Fiorina and other political scientists have shown with reams of data, that is precisely the shape of the American electorate: Most Americans can be found in the centre, not the extremes.

Of course that's not all there is to the story. As even casual observers of American politics know, Republicans and Democrats are miles apart on issues and this polarization seems much worse than in the past.

Unfortunately, that is one popular perception that is accurate.

The Pew survey shows a sharp increase in polarization in the views of ordinary Americans who identify themselves as Republicans and Democrats, particularly since 2000. That looks like a pretty dramatic contradiction of the claim that the views of the American public, as a whole, are largely unchanged. But it's not. Because it is primarily the result of ideological sorting.

In the pre-Reagan era, the parties were coalitions representing a broad range of ideological positions. Liberal Republicans were common. So were conservative Democrats. A substantial amount of heterogeneity lasted into the 1990s. But in the last decade, the parties have increasingly sorted themselves ideologically, making the Democrats overwhelmingly a party of liberals and the Republicans a party of conservatives. As a result, the divide between the two parties' supporters became much wider and deeper - even though the views of the American electorate as a whole changed very little.

The United States has major problems. Being "a nation divided" is not one of them.

*I'm taking a leave from the Citizen to write a book, so this will be my last column for 18 months. Keep the porch light on.