Have we killed Paul Thomas Anderson?

We are in Paris. The director is nearing the end of two days' publicity for his elegiac, pretzel- plotted adaptation of Thomas Pynchon's equally head-spinning Inherent Vice. He doesn't do many interviews. So, it's not altogether surprising that the experience has worn him down. But I didn't expect to enter the hotel room and find him stretched out statically on a well-stuffed couch.

Anderson shuffles awkwardly to his feet. A compact man with a beard significantly whiter than his pepper-and-salt head, he shakes himself awake and opens a window on to the rue du Faubourg Saint Honoré. Don’t tell the EU watchdogs, but we’re going to risk a cigarette.

“This part of the process has a melancholy to it: once the film’s out there,” he says, as we wrestle a table away from the window area. “But that melancholy part has passed. I’m already trying to get on to the next thing. I’m just waiting for a good idea.”

There will be more pressure on Paul Thomas Anderson than there would be on most directors. He's not the first man to be glibly identified as his nation's greatest film-maker. It happened to Martin Scorsese. It happened to Terrence Malick. None of them has savoured the focus that comes with such reductive adulation.

Following a fascinating misfire with his debut Hard Eight, Anderson turned heads with Boogie Nights and Magnolia. It was then decided that he was the new Robert Altman. Defiantly odd pictures such as Punch-Drunk Love (Adam Sandler in real life) and There Will be Blood (Daniel Day-Lewis as capitalist Mephistopheles) confirmed that he played to nobody else's rhythms.

"There's always a healthy amount of stuff to keep you humble and ensure you do not get too proud of yourself," he says with a cackle worthy of Walter Brennan.

Still, encountering that sort of praise, a man might easily get stage fright. Malick disappeared for 20 years.

“It depends how seriously you take that stuff. It’s f**king lovely to hear that about yourself. When you were a kid all you wanted was to get a film made. Now this. But that talk is disposable. You keep your head down. You run your race. You know how it is.”

Influences? What influences?

The search for key influences in Anderson's work leads only to dead ends and puzzling diversions. He has a dedication to self-conscious sound design – recently making use of Jonny Greenwood's extraordinary original scores – that seems in conversation with the avant-garde. He enjoys bravura camera moves, such as the famous opening track in Boogie Nights, but, as in much of Inherent Vice, he also employs sleepy, slow zooms. Is the singularity of his approach down to the fact that he is largely self-taught?

“Well, as opposed to what, I wonder,” he drawls. “I don’t know if film school teaches you to be a film-maker. Anybody that’s worth their salt will find a voice. Would Martin Scorsese have been as good if he hadn’t been to film school? I think he would, but he also got lucky and found teachers that opened his eyes.”

The son of an actor and voice artist named Ernie Anderson, Paul, now 44, grew up in that bit of the San Fernando Valley that abuts Hollywood. It seems as if, like many film-makers his age, he has been looking down a view-finder for as long as he has been walking. He began with video cameras and later developed a passion for 16mm film.

Hitting the credit cards hard

Myths have already gathered around the early years. He made money gambling. He ran up debts on credit card. However PTA managed it, before he was 30, he had Hard Eight and Boogie Nights in the can.

“Well early on I had a trial by fire on my first movie,” he says. “I got paranoid and real protective. I was bluffing my way through it. You mellow out as you get older. If you work with good people, you want their opinion. There is less fighting than there used to be. I used to think that I had to plant a flag and talk louder than anybody else.”

He pauses to ponder and tap some ash in the saucer. “You get yourself in a state of hypnosis on set that makes perfect sense to you,” he says. “You are at your best when you are unself-conscious. The worst part is when you are thinking too much. That can be a terrible place to be.”

I wonder if he ever had to fight for some of his more risky creative decisions. Consider Daniel Day-Lewis in There Will Be Blood. Nobody else but that actor could have got away with the hugeness of the performance as deranged tycoon Daniel Plainview. Did anybody ever suggest some toning down?

“Is his performance too big? I don’t think so.”

Nor do I. But did he ever have doubts?

“No f**king way. It was Daniel Day-Lewis,” he says with an even wilder cackle. “You just watch him go. Ha ha! That’s every kid’s dream – to get Daniel Day-Lewis in a movie. You’re flashing me back to watching him do it in the movie. That was so exciting.”

Anderson's subsequent film, The Master, featuring the late Philip Seymour Hoffman as manipulative guru to Joaquin Phoenix's troubled wanderer, felt like a worthy companion piece to There Will Be Blood. Inherent Vice is something else altogether. Whereas Blood was very, very loosely adapted from Upton Sinclair's Oil!, the new film is a crazily faithful take on Pynchon's 2009 detective yarn set in Los Angeles as the stoned 1960s give way to the paranoid 1970s. The book is more of a conventional narrative than Pynchon epics such as Gravity's Rainbow or V, but the plot is only marginally less complex.

"Adapting Oil! was to do with stealing some characters and situations," he says. "This was different. It came from a deep respect for Pynchon and the book. It was all there and it was just about figuring a way to make it a reasonably sized film. But, that said, it started to get good when we became less respectful to the book. It was better when we were out there. Being too precious about anything is bad. Mess it up."

What an odd thing Inherent Vice has turned out to be. Featuring Joaquin Phoenix as the chemically confused private investigator "Doc" Sportello, the film is fired-up by zany situations, but, with its crazily convoluted plot, demands serious attention from the audience. Long a devotee of Pynchon (the Dante of postmodernism), Paul Thomas Anderson now becomes the first director to film one of the great man's novels.

“I don’t know if it’s a shame that nothing has been made of his books before,” he says. “People may have done bad jobs. This did probably lend itself the best to adaptation.”

1970s fug

Although the film doesn’t fetishise the era, it is deliciously soaked in early 1970s fug. Even the film stock seems Nixonian.

“I had this film stock sitting in a garage,” he explains. “It was heat-damaged and when we filmed with it, it had that look like it was broken: very milky. When we saw that we just tried to make the whole movie look like that. You don’t see grain very much when you go to the movies any more. That’s a shame.”

Pynchon (though reportedly a very engaging personality) has, in a career lasting over half a century, never put himself before the public. Only a few photographs exist. He never does interviews. Inevitably, rumours began spreading about his involvement with the film. It is said that he can be spotted in a crowd scene.

When Anderson has, to this point, been asked about such gossip, he has spoken in oblique, guarded phrases. This has fuelled the suspicion that he has met Pynchon and has been told to remain silent.

He begins humming. He does some hawing. I tell them that I detect an ambiguous smirk.

“Oh, You Irish! You f**king Irish,” he says, directing a mocking finger at me. “Okay. Rather than being ‘oblique’, as you say, let me be unambiguous. I have never met the man. I have never met him. How’s that? Take that! Ha ha ha! But I can say that he’s a living, breathing human being.”

I think that counts as a revelation, Pynchonites. It may not be the one you were hoping for, but that’s all we’ve got. At any rate, Anderson is now very definitely awake.