CHICAGO - If Martians landed here and observed things for a while, they might reach the conclusion that Americans are deeply polarized on the stark choices they face: Coke vs. Pepsi, Big Macs vs. Whoppers, the Ford F-150 vs. the Chevy Silverado. It would take an actual human being to explain that though a few people have deep, passionate preferences, most of us don't perceive a huge difference between the options and could be reasonably satisfied with either.
Watching the Democratic convention - or the Republican convention, when it comes around - you could get the idea that on most issues, Americans stand on either side of a vast gulf, finding nothing in common with the people across the divide. Name your preference: Bill O'Reilly or Michael Moore? Tom DeLay or Edward M. Kennedy? Christian or atheist? Cowboy boots or sandals? Red state or blue state? On these choices, it looks as though the twain shall never meet.
The impression of a house divided is confirmed by the beliefs of the typical Democratic convention delegate. According to a New York Times/CBS News poll, delegates are far more critical of the Iraq war, far more worried about the federal budget deficit and far more opposed to restrictions on abortion than the average person.
Forty-four percent favor gay marriage, which only one in four Americans endorses. Just 19 percent of the delegates favor the death penalty, compared with 50 percent of Americans.
So is the Democratic Party out of step? Not any more than the Republican Party, if polls at the 2000 GOP convention are any indication. Looking at delegates, however, gives a misleading picture. Democratic voters in general are not nearly as liberal as the activists in Boston.
The Times/CBS poll found that 39 percent of Democratic voters endorse capital punishment. Fully 49 percent favor stricter limits on abortion. Only 36 percent support same-sex marriage.
What you see on TV, however, are the most committed, ideological - and, to be honest, sometimes the most mentally unbalanced - elements of the party. They no more typify Democrats than the Sears Tower typifies office buildings.
The major party candidates have plenty of things to argue about, but on many issues, they are not as far apart as you might assume. This year, both nominees supported the Iraq war resolution, favored the Patriot Act and plan to cut the deficit in half by 2009.
John Kerry criticizes President Bush's handling of the Iraq war, but his remedies don't sound much different. When it comes to the issue Republicans prefer to keep front and center, namely tax cuts, the Democratic challenger promises to cut taxes for 98 percent of Americans.
Though Mr. Kerry supports abortion rights, he also asserts that "life begins at conception." His health care plan is designed to expand the competitive system of private health insurance we have today, not replace it with a universal government-provided entitlement.
But supporters of Ralph Nader or the Libertarian Party are wrong when they say there's not a dime's worth of difference between Mr. Bush and Mr. Kerry. I'd guess the difference amounts to at least 15 cents.
The reason the parties are pretty similar is that Americans are just not all that divided on important matters - as documented in the new book Culture War? The Myth of a Polarized America, by political scientists Morris P. Fiorina, Samuel J. Abrams and Jeremy C. Pope. Partisans hype the differences between red states and blue states, but the authors note that even in red (Republican) states, a majority of residents express a favorable opinion of the Democratic Party, while 50 percent of blue-state voters think well of Republicans.
"Across a range of other matters, blue and red state residents differ little, if at all," they report. Looking at public opinion on a long list of issues, from school vouchers to estate taxes to Medicare prescription drug coverage, they say, "one wonders why anyone would bother separating respondents into red and blue categories - the differences are insignificant."
So when Illinois state Sen. Barack Obama said in his keynote address, "We worship an awesome God in the blue states, and we don't like federal agents poking around our libraries in the red states," and, "We coach Little League in the blue states and have gay friends in the red states," he was not just turning clever phrases. He was dramatizing a truth that is easy to forget during a bitterly contested election campaign: We're not two nations, but one.
Steve Chapman is a columnist for the Chicago Tribune, a Tribune Publishing newspaper. His column appears Tuesdays and Fridays in The Sun.