In one of the most touching moments in "Life Goes On," Libby Thacher (Patti LuPone) goes into her room, puts on her Woodstock minidress and starts singing "Born to Be Wild." Depressed about turning 40, she complains to her husband, "You used to be really turned on by this dress."

The scene is one of many on television in which characters try to square '60s ideals with '80s realities. It's not a trend that started this year. You can see it in "The Wonder Years," in which a more jaded man of the '80s looks back at his naive youth in the late '60s. You can see it in "Thirtysomething," in which the characters pine for lost ideals.

Besides "The Wonder Years," two other series are set in the '60s and ask questions (albeit badly) about that decade's defining event, the war in Vietnam -- "China Beach" and "Tour of Duty."

Some borrow the music ("Murphy Brown"); others borrow the values ("Head of the Class"); and others borrow the attitudes ("Wiseguy" and distrust of the government).

The trend is even more pronounced this year. Despite the emphasis on family unity since the success of "The Cosby Show," the generation gap is back in full force on "Wolf," in which father and son are constantly at each other's throats, and, to a lesser extent, in the ethnic comedies "Chicken Soup" and "The Famous Teddy Z," where running jokes will obviously be Jackie Mason's and Jon Cryer's inability to persuade their grandmother and mother, respectively, that it's OK to mix outside their ethnicities.

"Alien Nation" appears to be a metaphor for the black experience in America, with aliens taking the place of blacks, but it seems more closely tied to the black experience of the '60s: Alien integrationists argue with human racists on the one hand and alien separatists on the other.

Two of the season's new characters, the zoo manager (Lindsay Wagner) in "Peaceable Kingdom" and the young congressman (William Katt) in tonight's "Top of the Hill," are unabashed '60s-style liberals trying to reconcile their beliefs with today's political realities. And two others, "Major Dad" and tonight's "Hardball," pair a liberal and a conservative in ways that dimly recall "All in the Family."

What's going on? Mostly an attempt to appeal to baby boomers whose presence is required by advertisers for a program to be a major success. They have the primary buying power in the country now, so whatever boomers want, boomers get. And apparently, what network executives think baby boomers want are programs that, however remotely or however superficially, deal with '60s values.

If that doesn't jibe with the last election, it does jibe with Arthur Schlesinger's 30-year-cycle theory, which says that what went around in the '60s will come around in the '90s. Perhaps that's wishful thinking on Schlesinger's part, or perhaps the last election had more to do with Michael Dukakis' failure to articulate liberal values in 1988.

But for better or worse, the '60s are back with us. In the case of tonight's two programs, "Hardball" and "Top of the Hill," it's mostly for worse.

* * Hardball 8:30 tonight, Channel 4 Then 9 p.m. Fridays

"Hardball" has the virtue of the new season's most charismatic star, Richard Tyson. And what a '60s icon he is. Hair past his shoulders. Work shirts and jeans. Distrust of authority. He speaks in '60s aphorisms like "Riddle me this, Batman," and shuns '80s buzzwords, as when he sarcastically says, "I just love that male bonding stuff."

His partner, though, could be Archie Bunker's younger brother. John Ashton is a Dick Butkus lookalike who, as Charlie Battles, takes one look at his new partner and says, "They told me I had some hot shot from Riverside. Instead I get Yoko Ono." His taste in music runs to Barry Sadler's "Ballad of the Green Berets."

After the first two set-up scenes, it looks as if "Hardball" is going to be the second coming of "Miami Vice," complete with high-energy camera work, moral ambiguity and a John Fogerty soundtrack. But that's only the bait to keep us watching. "Hardball" soon switches to the second coming of "Starsky & Hutch."

It's better than that, thanks to the two main actors and some witty writing. But the plot is tepid, the love story between Ashton and guest Kay Lenz is hackneyed, and everything else about the show reeks of leftover buddy-cop cliches despite Tyson's nouveau wit.

"Hardball," because of Tyson's magnetism, may be the kind of program that teen-agers love, and because of its violence, may be the kind of program parents hate their kids loving.

* Top of the Hill 9 p.m. Thursdays, Channel 7

Now here's a show we can all get together and hate. Teen-agers. Parents. Singles. Marrieds. Left-wingers. Right-wingers.

It's a program about a Democratic congressman produced by a Republican producer, Stephen J. Cannell, who says he didn't want people to think he was using his show as a platform for his beliefs.

After watching "Top of the Hill," liberals will be only too glad to give him his platform. Cannell has had a checkered career, producing intelligent programs like "Wiseguy" and "The Rockford Files" on one hand and dimwitted shows like "The A Team" and "Riptide" on the other.

"Top of the Hill" is "The A Team" meets "Mr. Smith Goes to Washington." William Katt is the James Stewart character who inherits his father's congressional seat, but at the drop of a constituent's hat turns into George Peppard, ready to take on the drug barons -- or, to use Dan Rather's terminology, the drug scum -- of Central America.

Katt, on first appearance, looks as much like a hippie as Tyson. He hears a constituent saying, "I've been to the DEA, the BFA, the FBI. I want this government to, for God's sake, help me."

His ailing father, a party hack, is still around to help groom him, in more ways than one. He's forever trying to get him to cut his hair, and he's forever trying to get him to play the insider's game, particularly with the party whip, wonderfully portrayed by the late Kenneth McMillan, who almost makes the two-hour premiere worth watching.

There are some other nice touches. Katt, or Thomas Bell, is not going to get clean victories. He laments at the end of the program, "The drug dealer is still selling dope, the bank is still laundering money and I voted for something I'm absolutely opposed to."

On the whole, though, "Top of the Hill" is less interested in Washington than in locking into contemporary prejudices about the way government works -- and doing so in the most hackneyed of ways. The mix of action-adventure is patently ridiculous.

Thomas Bell may be the prototype of a successful liberal politician, but "Top of the Hill" has loser written all over it. In the end, as they say, the people will decide. Here's betting on another landslide election for "Cheers" at 9 p.m. on Thursdays. siegel;09/20