A select group of Washington's political and media leaders gathered last night to preview "I Love Liberty"--a new swing by Norman Lear through the ever-revolving doors of social issues and entertainment.

Best known for bringing the social stereotype of Archie Bunker into American living rooms, Lear began the $3-million, two-hour film as a portrait of patriotism. A liberal at heart, Lear wanted to show that Democrats, and not just conservative groups, can inspire patriotism.

"The extremists have never had a problem in claiming patriotic symbols as their own," Lear said before last night's screening at the Motion Picture Association of America. "This film is not for the right or the left," he said, "but for the middle--for the broadest base of liberals and conservatives."

Lear said he believes that liberals as a group are capable of rousing middle America and inspiring patriotism. The problem "is that we've seldom tried. We just don't do it."

Lawyer Peter Edelman, a former aide to Robert Kennedy, offered another view. "The major reason is that liberals generally see the complexity of things and they tend not to oversimplify," he said. "The right appeals to simpler values. People are not forced to deal with ambiguities and complexities."

Before the screening, a casual dinner of fried chicken and chili was served to about 60 guests. Among them was a cross section of politicians, from a liberal voice of the Senate, Alan Cranston (D-Calif.), to conservative Paula Hawkins (R-Fla.), whose Senate race was supported by the Moral Majority.

"Recently they the Moral Majority have done better at inspiring patriotism, but the Democrats have in the past and will again," said Cranston, a friend of Lear's. "Norman's show will make a difference. It can help tremendously. And the opposition we're seeing to Reagan's mistakes, as well as our own creativity, can enlist the support of the American people again."

Hawkins, who said the Moral Majority supported her because of her "chaste, girl scout image," walked a fine line between praising and criticizing the Moral Majority last night. "I don't think it was really what the Moral Majority did or said that upset people, I think it was the quantity of the negativism," said Hawkins. "In America they have the right to do whatever they want."

To emphasize the bipartisan nature of the project, Lear invited former president Gerald Ford, Lady Bird Johnson and Walter Cronkite to lend their names as sponsors.

The show, filmed last month at the Los Angeles Sports Arena before an audience of 12,000, will be televised by ABC Sunday. Its stars, as philosophically diverse as Jane Fonda and Barry Goldwater, sing, dance and perform in re-creations of historical events. And the Muppets--as apolitical a group as you can get--reenact a session of the Continental Congress.