Meet Nathan Fletcher, candidate for mayor of San Diego.

He will lose, at least if the polls are right. But he has raised a minor stir through a video posted online a few days back. In it, he explains his decision to leave the Republican Party and identify henceforth as an independent.

"I don't believe we have to treat people we disagree with as an enemy," he says. "I think we can just say sometimes we disagree. … I've fought in a war," adds Fletcher, a Marine who served in Iraq. "I have seen the enemy. We don't have enemies in our political environment here."

Fletcher's decision has been scorned by observers from both parties as a desperate gamble by a guy trying to shake up a flagging campaign. Maybe it is. But that doesn't denigrate the essential truth of what he said, and in particular, that word he used: enemies.

It is a telling term. After all, one might negotiate with an "opponent." One only contends against an "adversary." But one seeks to destroy an enemy.

And it makes you wonder: Is that really the way we the people see ourselves? The evidence of recent years suggests that it is. The so-called culture wars – a battle of ideas and ideals concerning abortion, faith, gay rights, gun rights, Muslim rights, global warming, health care, immigration – are fought with splenetic bile that would have been unthinkable not too very long ago.

But that was before a congressman heckled a president, before guns were brought to presidential appearances, before a radio host called a college woman a "slut," before someone set a fire at the construction site of a Tennessee mosque, before "I want my country back" became a rallying cry. It was before there grew this gnawing sense that we do not know each other anymore, that the extremes are pulling the center apart.

Nor is Fletcher the only one to notice. Sen. Olympia Snowe, a Republican moderate, announced her retirement a little over a month ago, blaming the dysfunction and polarization of American politics.

One is tempted, in the spirit of moral equivalence, to ascribe blame for this polarization to both parties, but that is simply untrue. For all their sins of ineptitude, infighting, cynicism, and even occasional name calling, it is not the Democrats who have gone off the ideological deep end.

The party has not championed same-sex marriage or gun confiscation, much as some of its constituents might want it to. It compromised on health care and the Bush-era tax cuts, much as some of its constituents wish it had not.

No, it is the GOP that has abandoned the center and embraced ideological extremism as a virtue. It is telling to hear its candidates use "moderate" as an epithet and argue over who is the most "conservative," as if the word contained some pixie dust of common sense and moral rectitude. It is sobering to realize that Ronald Reagan, patron saint of modern conservatism, would be unelectable by the standards thereof: he raised taxes and was known to compromise with political opponents – not "enemies" – to get things done.

That was then. His party has since engaged in a 30-year flight from the center that reaches its nadir – at least, let us hope it's the nadir – in this era of tea party incoherence, faith-based policy, fear mongering and tax pledge tyranny. This is an era when compromise is both lost art and dirty word, and some Americans see other Americans as enemies – an era in which there is something lonely and foregone about pleading with an angry nation that this is not how it is supposed to be.

As one Republican once put it, "We are not enemies, but friends. We must not be enemies."

For the record, Nathan Fletcher did not say that. Abraham Lincoln did, 39 days before the beginning of the Civil War.

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