Forgiveness is not the quality that candidates usually seek to evoke from their constituents. Approval and enthusiasm are what incumbents commonly hope to arouse; anger and discontent are the emotions challengers try to stir.

But this year President Reagan and his opponent, Walter Mondale, are trying, in their own ways, to seek forgiveness -- at least, in this early stage of the game.

Indeed, the first four words of the first speech of the president's general election campaign were: "You will forgive me . . ."

The rest of the sentence was a Reaganesque clich,e. "You will forgive me a little home-state pride," he told the Labor Day throng in Irvine, Calif., "but I can't help but thank you for giving me an opportunity to get away from those puzzle palaces on the Potomac to return home to kick off our campaign."

That's all there was to it. But it got me thinking that, in a more basic way, Reagan's brimming confidence is based on his belief that "you (the American voters) will forgive me (Reagan)" an awful lot.

They always have, as Rep. Pat Schroeder (D-Colo.) commented ruefully in her classic description of Reagan's "Teflon-coated" presidency -- one to which no criticism sticks.

In this campaign, Reagan and his managers are hoping the voters will forgive and forget a great many of the policies and personalities that stirred controversy in the past 44 months.

People such as James Watt, Anne Burford and Alexander Haig, whose very names were enough to stir angry debate, have mostly been dropped overboard -- or, as with Edwin Meese and William Casey, put out of sight for the duration of the campaign. The only time you hear their names is when a Democratic orator brings them up to get the crowd booing, as Rep. Les AuCoin (D-Ore.) did at a midweek rally here.

While pointing with pride to his record in reducing inflation, boosting real income and slashing taxes, Reagan would like people to forget the worst recession in 50 years, the growth in officially counted families in poverty and the quantum leap in the size of the annual federal deficits.

He would also like them to forget the fiasco of his Lebanon policy -- and the lives of the Marines lost there. There were briefings galore on the anniversary of the brutal Soviet downing of Korean Airline Flight 007, but no ceremonies marked the Aug. 29 anniversary of the death of the first Marine in Lebanon.

On the other side of the political street, the Mondale campaign's search for forgiveness is alternately stark and subtle.

Mondale would most like people to forget his role as Jimmy Carter's vice president, and the legacy that administration left of inflation, economic stagnation and captive hostages. He would like farmers to forget grain embargoes; home-buyers to forget, double-digit interest rates; and everyone to forget "malaise."

There are parts of his own Senate record he would like to erase: for example, his vote against the thriving space shuttle program. He would be grateful if voters would also overlook what his rivals for the Democratic presidential nomination said about his record on defense, his penchant for spending and his ties to organized labor and other interest groups.

There is also a more subtle kind of forgiveness the Mondale campaign is seeking from voters -- a willingness to accept a presidential candidate with a less vivid and attractive personality than the incumbent.

In conversations this week with two senior Mondale aides and advisers, Mondale's chance of success was linked directly to getting the voters to feel "comfortable" with him as he is.

A top Mondale operative in California said that the state registration drive, aimed at adding half a million low-income and minority men and women to the voting rolls, would not be enough, nor would Mondale's challenge to Reagan's environmental, education and arms control policies, unless swing voters get "comfortable" with Mondale. "They don't have to like him," he said. "They like (vice- presidential candidate) Gerry Ferraro, and they like Gary Hart, who's giving us 10 days of campaign time in California. All they have to do is get past feeling uncomfortable about Mondale."

Another Mondale adviser with Illinois roots said he was not counting on Mondale's strength to carry that state. "Harold Washington (the Chicago mayor) and Eddie Vrdolyak (the Cook County Democratic chairman and critic of Washington) both have their own reasons to turn out the votes in the black and ethnic wards they control," this man said. "All Mondale has to do is defuse the antagonism in the suburban townships, so he doesn't end up like McGovern or Carter, with less than one-quarter of that vote."

Forgive Ronald Reagan for his blunders and for his friends, the Republicans seem to be saying. Forgive Fritz Mondale for his history and his blandness, the Democrats implore.

It is a curious campaign.