Paul Thomas Anderson Told Us Why He Turned a Thomas Pynchon Novel Into a Movie

I was in Gloucester, Massachusetts when I first read Inherent Vice. It was July of 2009. I was there for the summer and I got an advance copy off the publisher. Any time a new book of Pynchon's has come out – at least since I've been around – it's like I hang the Do Not Disturb sign on the door and don't come out until it's done. It took me a couple days to do it.

I remember it quite well, sitting there, reading it and thinking, 'I'm never going to make this into a movie.' I felt the same about Vineland. I thought about making that into a movie before, but I just couldn't figure it out. It's like Gravity's Rainbow – I've never got through it.

I also remember thinking, when I read the book, 'This is like The Big Lebowski.' And that was a reason not to make the movie. That was a reason to say, like, "Why would I have to do something like The Big Lebowski? Why would I even come close?" But the more I looked at it, the more I loved the book, and I had to kind of ignore that and pretend like it didn't exist, because, you know, The Big Lebowski is the best movie in history. So I just ignored it and thought about it a different way.

I think part of the fun of Inherent Vice is to get just completely tangled up in the many loose ends and overwhelming information, which is meant to be part of the joke in the book. You're either going to think, 'My head's going to explode and I give up,' or, 'My head's going to explode and it feels kind of fuzzy.' I wanted the same for the film.

I didn't change a great deal from the book. The main thing I did change was this character that Joanna Newsom plays, Sortilège. In the book, she was this great supporting character who floated around and would give Doc acid or give him astrological advice – that kind of stuff. I took that character and made her a bit bigger and gave her narration and made her more of a sidekick. Kind of like Tinkerbell. When I read that character it reminded me of Joanna, so I asked her to do it. Joanna hasn't done acting before, but I know her personally through her husband – our families know each other – and, you know, she's kind of got that hippie spirit. She just has that oozing out of her, the way she looks and the way she talks and the way she sounds, she's just so fucking cool. She was perfect.

This story that Pynchon was telling was obviously autobiographical and from his generation and from his heart. I wanted it to feel like it was from that time, to try and make it feel authentic to that era, almost like it was a kind of faded postcard – a picture you might see of your parents in a drawer that's faded in colour a little bit. We just tried to be accurate in terms of what people were wearing and what people looked like. Los Angeles at that time was a little bit hazier because there was so much smog, so we also tried to give it a little bit of that look.

The fact that it was California felt right to me for sure. It's all so familiar to me. It's home, so that part of it was very appealing, to work in these places that I knew very well. But the era was kind of new to me, and that was exciting. I was only a kid in the 1970s, and my parents weren't hippies, but I'd get nauseated by my parents' friends who were. You'd hear them talk about the 60s like, "Oh man, it was so great. The drugs and the music were so great." And you were like, "Ah, fucking hell, enough of that!" But I think what they were on about wasn't necessarily the drugs or the music, but the feeling that there was a revolution that was about to happen – but it ultimately fell away and slipped through their fingers.

I don't know if I'll ever adapt a book again. I know I still have original things to write, but if another book comes along, I'll adapt that. I have no real plan. Magnolia was probably my most personal work, and I learned that, if you write something really personal at a current time in your life, then you feel it flow through you but you sort of know instinctively that you'll never be able to get back there again. That you'll never be able to revisit that moment in time.

In that sense, starting from scratch can be quite dark and lonely work, but it's less lonely adapting a book because you're working with something else.

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Thomas Pynchon is a reclusive novelist whose works are infamously dense and convoluted. Yet, his clever metafiction and ability to put the paradoxes of life on paper have seen him lauded as the great American voice of postmodernity.

The writer's fourth novel, Inherent Vice, is a psychedelic noir-thriller following the fortuitous and not-so-fortuitous encounters of Doc Sportello, a stoner PI operating in 1970s California. Paul Thomas Anderson's adaption is in UK cinemas from the 30th of January.

Look out for our interview with Paul Thomas Anderson on Monday the 12th of January.

As told to @MillyAbraham