Considering the general flood of television programming, it's startling to realize that at the height of its popularity in the 1980s, "Family Ties" ranked as one of the most-watched shows not just of the moment but in the history of television.

Watching four episodes just released on videocassette by Columbia House, one might wonder why, but there is no doubt how well a top sitcom can serve its era before passing on."Family Ties," which ran until 1989 and then disappeared as if on cue, was perfectly geared to its decade. When the show began in 1982, Ronald Reagan had been in office for almost two years and the country was turning sharply conservative, getting down to raging materialism and becoming acquainted with a species called the yuppie.

"Family Ties," in fact, went on to become Reagan's favorite show. As written by Gary David Goldberg, its creator and producer, the story involved two hippie refugees from the '60s, Elyse and Steven Keaton (Meredith Baxter-Birney and Michael Gross), and their three children, who were quintessentially of the '80s.

Most famously, of course, there was one Alex P. Keaton, a baby-faced half-pint of a 17-year-old with a political rudder stuck hard right and greed that flowed like sap. In perhaps the decade's most fortunate bit of casting, Alex was portrayed by Michael J. Fox, a young man of angelic looks and the beautifully realized manner of a middle-aged country-club board member.

"Do you think he was switched at birth and the Rockefellers have our kid?" Steven asks Elyse in the pilot, by far the strongest episode on the cassette. Not to overstate the case, but Fox, star of "Spin City," Goldberg's current comedy, was the major reason for the show's popularity.

In its concerns with parental authority, teenage insecurities and the like, "Family Ties" had all the familiar ingredients. But as it evolved, the show took the family sitcom on a radical course correction.

For laughs there were topical chuckle points: The Wall Street Journal alarmingly turning up under Alex's bed, the pop wine quiz at dinner. Deeper things were going on, however. Suddenly in the person of Alex, and to a lesser extent his siblings, the balance of power shifted from omnipotent parents of sitcoms past to bright, more mature offspring who stood up for themselves.

On "Family Ties," in fact, it often seemed that the children had taken control from Elyse and Steven, who in the permissive traditions of their own era restrained themselves from cracking down the way parents had back in the sitcom days when Father knew best. On "Family Ties" the children loved and honored their parents in most of the ways Americans want to see in family shows. But childhood was never the same.

"Dad, I need to talk to you," Alex sternly tells his father after the elder Keaton has let his emotions and '60s sensibilities get away from him. Storming a country club in protest over its racist membership policies, Steven accosts Alex (bunny-hopping on the dance floor with the blond and elitist Kimberly Blanton), vents some spleen and tries to drag his son away.

Back home, Alex, embarrassed and furious, makes no bones about his displeasure at what he considers the childish actions of his father.

"Dad, I'm 17," he says. "When I see Kimberly Blanton in a strapless gown, I don't look past her for the Bill of Rights."

Steven sheepishly explains himself, or tries to, and apologizes. In a little episode wrap-up, father and son reconcile. "We're both getting older," Steven says. "One of us is bound to grow up sooner or later." Better get working on it, Steven.