"THE liberals have nothing to say," Saul Landau, one of the most committed liberal filmmakers, announced after a recent showing of his film, "Quest for Power," on figures of the new right. "There's no answer to these people." His audience, for the most part, was a group of like-minded, well-schooled liberals crowded into a conference room at the Institute for Policy Studies, where Landau is a fellow.

"The ACLU American Civil Liberties Union basically says that one idea is as good as another," Landau said. "The right says, 'No, that's not true. There are right ideas and they are the ones that should be taught.' I take them very seriously."

He also takes documentary filmmaking very seriously--though he defines it differently from the way his former bosses in public television probably would.

"Documentaries are no more real than feature films," he said, a day later. "Documentaries use amateur actors. Feature films use professional ones. We've just boxed ourselves in with this objectivity. It's just a sense of grammatical rules."

In his 16 years as a filmmaker--the last 13 as an independent one--he has applied his techniques to subjects found in the Latin American, as well as the American, political scene. The results have sometimes been compelling: His 1979 film, "Paul Jacobs and the Nuclear Gang," won the George Polk Award for investigative journalism and an Emmy for best documentary. In 1971, he and cameraman Haskell Wexler interviewed Brazilian political prisoners who had arrived in Chile as part of an exchange for a kidnapped Swiss ambassador. That became "Brazil: Report on Torture."

"That's one of my favorite films," Landau said. "We said, 'Look, we'll do this film and show it in America--show that there is torture.' We got them to show what kind of torture there was. They reenacted it." But not too much, he said. "We didn't want a Hollywood hoke 'em up . . . They talked about it almost matter-of-factly. They weren't all political activists. Some were lawyers, some were priests, some were med students . . . People say there's no equality in Brazil--not true. Everyone can be tortured--rich and poor."

His own politics: "I'm a Democrat with a small 'd'. I think socialism is a much better system. I don't see it happening in my lifetime here. Unfortunately, we've had to equate socialism with the Soviet Union."

He doesn't call his films political. "They're educational," said Landau, also an author who wrote, with John Dinges, "Assassination on Embassy Row," a book about his late friend and colleague, Orlando Letelier. "The word, 'political' is so funny in this town. It's the lowest form of activity . . . All my films try to teach people without preaching too hard," he said. "I try not to be too tendentious."

But even his own patrons at the Institute for Policy Studies, with which he has been associated since 1972, have been known to get a little nervous about his work, he said. "Years ago, we made a film about Congress called 'Who Shot Alexander Hamilton?' " said Landau. "I liked the film. Dick Barnett and Mark Raskin, the founders and codirectors of IPS said, 'If this film comes off, we'll never have any relations with Congress again.' But everyone in the film loved themselves."

Landau's 1968 film, "Fidel," is a portrait of Fidel Castro: "He takes us on a long Jeep trip through Cuba, plays baseball, chats with peasants, goes back to his nursery school, listens to complaints," said Landau, who speaks Spanish fluently. "He makes speeches in the pouring thunder storms. He loves to make events. It's one and a half hours long. It's how the revolution looks to him. That was the first look at this man outside of news clips."

Landau mentioned the idea of the film to Castro at the Cultural Congress in 1968 in Cuba, and he agreed to it. Castro had told Landau he liked the filmmaker's 1967 documentary, "Report from Cuba."

"I found Fidel a sympathetic figure and a hell of a good actor," said Landau, making no apologies for his film. "You have 999 anti-Castro films. So why don't you run one pro-Castro film?" The first night the film was to play at the Fifth Avenue Cinema in New York, the theater was bombed, he said. No one was inside at the time.

"I think I'm objective," Landau said, "but I'm not detached. That's why I make films . . . to raise people's consciousness in one way or another. Why do all this work? Filmmaking is a horrible, grueling job, being uncomfortable in a Third World country. Your network documentary is done by people who don't care--cuz one day they're in Nepal and the next day they're in Taiwan and the next day, they're doing a story on ghetto children."

Two months ago, he filmed in Nicaragua on the Honduran border where hostilities have turned into serious clashes between Sandinista soldiers and counter-revolutionaries.

"People don't understand why the Third World wants to control the media," he said, sitting in a film cutting room, looking over his Nicaragua footage. "Anybody who's seen the news in America realizes it doesn't say anything about what's going on in those countries--where the problem is grinding poverty. Everyone talks about whether Nicaragua is a Marxist-Leninist country. Who cares? These people are on the edge of falling off the globe."

Money is tight. "We get a little money from the Stern Fund, a little money from the Rubin Foundation," said Landau, whose films generally play the festival and art house circuit. "But we don't do them for much money. When Haskell [Wexler] does work, he doesn't get paid. He brings his own camera.