His films are a divorced child's films, Cedric Klapisch tells Nick Hasted. They are fantasies of bringing people together.
Cedric Klapisch liked to watch. He wanted to be a director, even as a child. He liked the distance films gave him from the world. When he was 12, he began to take photographs. He'd take them all the time. When he was 17, going on holiday, he left his camera behind. It was like someone had died, like a part of his body had been torn away. He knew his voyeurism was killing something in him. He knew it was a sickness he needed to cure.

It's the subject of the film he's best known for. When the Cat's Away's tale of a young woman looking for her lost cat looked lightweight and lovely to some. But it's also about a woman leaving the insularity of her flat for the rigours of the world. At first, she walks the streets with suspicion. Klapisch's camera is behind her, she looks nervously back at each person she meets. By the end, she's rejoined her community. Klapisch took the same steps himself. But it wasn't his room he left behind - it was his camera.

"I had the tendency between 18 and my twenties to not watch," he remembers. "I really wanted to have experience. Then when I started to make films, I went back and forth. There's a sentence I like from Camus. He said, "In life, there are two moments. There's a time to live. And a time to testify." I really agree with that. In order to watch well, you need to live. You can't see how life works if you don't experience it. That's something I understood at one point in my life."

The 36-year-old Klapisch seems a long way from his childhood isolation now, the clammy world of watching from a distance. Talking above the din of traffic in a Soho office, he's generous, interested. But his engagement's been a long time coming. His second film, Le Peril Jeune, was about the death of the radical France of 1968 in the early 1970s, and until recently, he felt no interest in politics. It's only with the current French trend for issue-based movements that he's become involved. Small enough to allow individual thought, large enough to encourage social action, they're like the community the When the Cat's Away girl finds outside her door. The film seems to suggest that such bonds are natural, that it's only fear that keeps people alone. Is he really so idealistic?

"I think it's easier just to be afraid," he says carefully. "It's more difficult to overcome that fear and go out.

"I think that everyone is racist, for instance. In order not to be a racist, you have to make an effort. It's the same thing with love. In the film she's frightened of men, and she has to make an effort to not be frightened, to admit that she's attracted. I think that there is always that fight. It's easier not to do anything, and be selfish and racist and disinterested in other people, it's an effort to go out and see them. It's an effort that's worth it. Any connection that exists between people can only exist when you fight." Is that true for him? "It's true for me, it's true for you. I think it's true for the period. The tendency to stay at home is killing us."

Klapisch's films fight isolation in subtle ways. They ignore the picture- postcard view of Paris favoured by many parisiens, show the beauty of poorer streets, constant change and construction, they're soundtracked not by accordions but African pop. Most intimately, they're concerned with how people get on in groups. In his narratives and on his sets, Klapisch has said what concerns him most is families. Is it his own family that he draws from ?

"It took me a long time to understand that all of my films were talking about what I was experiencing with my family," he admits, "because my parents divorced when I was one.

"I'm interested in how the group can connect, or not. I think that's what interests me in all of my films. They're really a divorced child's films. They're fantasies of bringing people together." Klapisch's latest, Un Air de Famille, may be the nearest he's come to those concerns. It's written by others, and he didn't feel close to it at first. But, as the owner of a cafe and his family find their relations slowly cracking in the cafe's closed confines, it's clear why he took it on.

At first, the family seems monstrous. By the end, they're just people - relatives, striving to relate. "The film shows that hate is close to love," he says, "and that cruelty is close to gentleness. In a family, those things that are opposite live together. As a parent, your love for your children must teach them how to grow away from you. There's a kind of tragedy inside the idea of a family."

Un Air de Famille has a sharp, funny surface, it's claustrophobically bitchy. But, like all Klapisch's films, its undercurrents are serious. There's a scene in which the cafe's barman, treated almost like a slave by the bourgeois family, steps in and hits one of them. It looks like class politics.

"He was an observer the way the script was written," Klapisch corrects me. "I added that scene. It's like what I told you about myself. He was an observer, but he had to have contact in the end. He had to engage himself in a fight. He couldn't stay watching forever."