“In which direction would John Kerry lead?” asks the voiceover before launching into a list of Kerry’s changed positions. The ad shows striking images of John Kerry windsurfing off Nantucket, zigzagging on the water. The voiceover concludes: “John Kerry. Whichever way the wind blows.”

The ad was clever and effective — and had unintended consequences.

It helped make “flip-flop” an acid term of ultimate political disparagement. And it may be one reason our presidential candidates cling to some positions too long.

Flip-flopping hasn’t always been this unpopular. Wise men have praised reasonable change. Ralph Waldo Emerson said “Consistency is the hobgoblin of little minds” and counseled a willingness to change everything every day.

Winston Churchill didn’t go that far but quoted Emerson in his essay “Consistency in Politics,” in which he wrote, “it is evident that a political leader responsible for the direction of affairs must, even if unchanging in heart or objective, give his counsel now on the one side and now on the other of many public issues.”

As Cardinal John Henry Newman put it, “To live is to change, and to be perfect is to have changed often.”

A certain willingness to change is healthy and necessary. Many have complained that George W. Bush is too unwilling to change. But there can be too great a willingness to change, as when Bill Clinton went in search for his own core beliefs.

There are clear questions to ask in judging flip-flops. Did the politician’s change of heart lead him to embrace something truer? Or did it lead him away from the truth out of political expediency?

There have been some terrible flip-flops over time that spoke poorly of the politicians involved. For instance, Al Gore, Ted Kennedy, Tom Daschle and Jesse Jackson each went from passionately pro-life to unbendingly pro-abortion. That was representative of a larger flip-flop: The Democratic Party became the reliable servant of the abortion industry.

But there have been some beneficial flip-flops, too. The Democratic Party went from standing for slavery and segregation to fighting for racial equality, a turnabout symbolized by Sen. Robert Byrd, who was once a Ku Klux Klan leader and is now a Democratic Party leader.

Republicans flip-flopped from isolationism to leading the charge and defeating Hitler and communism. That was best summed up by Sen. Arthur Vandenberg who, during Truman’s administration, signed on to Truman’s interventionist anti-Communist foreign policy and basically invented the slogan that “politics stops at the water’s edge.”

We bring up these encouraging examples because we hope that the current candidates will have the courage to change in ways that are beneficial to the country and are more in line with natural law.

Barack Obama

The New York Times recently took note of five Obama flip-flops and dubbed him “The New and Not Improved Barack Obama.” His reversals: campaign fundraising, wiretapping legislation, allowing Christian organizations to get federal grants, the death penalty and gun control. The editorial ends with the blistering remark: “This country needs change it can believe in. “

We are more understanding of Obama’s flip-flops. None of his new positions seem fundamentally opposed to common sense or the natural law. In fact, we would like to see more flip-flops. He once wrote an essay about how troubled he was by Alan Keyes’ assertion that Jesus wouldn’t vote for him. He should follow his conscience and acknowledge the right to life of:

Children born alive during abortions (Obama opposed Illinois legislation that would protect them).

Children in the process of being born (Obama supports partial-birth abortion)

Women being kept alive by ordinary means (Obama says it was a mistake for the Senate to try to help Terri Schiavo, who was starved to death).

John McCain

Salon magazine recently published an article about McCain called “Flip-flopping to the White House” that listed McCain’s reversals. These included: “his position on offshore oil drilling (from opposed to in favor), on sweeping immigration reform (from in favor to opposed), and on tax cuts (from opposed to in favor).”

We’d like to him to add two more to the list:

Unequivocal support for traditional marriage (both Obama and McCain helped kill the Federal Marriage Amendment in the Senate)

No federal funding for embryonic research

Ultimately, what a candidate changes and what he won’t change tell us much about who he is. We hope both candidates will have the courage to hold fast to the truth — or to flip-flop to the truth — whenever their conscience sees it.