THE world's largest philosophy and music festival is back, as HowTheLightGetsIn presents a programme of thought-provoking debates, infectiously danceable music, comedy, and its now legendary parties.

This year's theme is Heresy, Truth and the Future, and the festival will offer the opportunity to find out which of today's heresies Diane Abbott, Roger Scruton, Lee Smolin, Brooke Magnanti, Chris Huhne and many others think will become the truths of tomorrow.

"One of the central things that the festival has always been about is to make big ideas not only relevant, but also something we feel comfortable talking about," says HowTheLightGetsIn founder and director Hilary Lawson. "There's something about British culture that means everyone is a bit nervous of philosophy. It may be that it's perceived as a bit difficult but there's also a sense that we (in this country) don't engage in that kind of chat, we leave it to Parisian taxi drivers.

"The festival," he adds, "is about realising we are all philosophers. Everyone worries about their own life or what's going on in the world. Being alive is a strange and mysterious experience.

"Philosophy has a reputation as being difficult, which is about the way it's been approached in the past. We are changing the way people think about big ideas and philosophy. HowtheLightgetsIn has grown 20-fold in the five years since it started." and this year sees the addition of a new venue a few hundred yards down the road from the Globe.

"When we started, lots of people said to us, 'who's going to turn up to a philosophy festival?'

"We were very nervous about using the word philosophy but now we are changing all that, realising that there's nothing to be nervous about.

People imagine philosophy will be an abstract conversation about the meaning of words and language and it's not like that. What we understand to be philosophy are the big ideas that underpin things, and that's what we talk about. "

This year those big ideas include The Banality of Evil, Life's Secret (is there a purpose to life?), The Science of Sex and Stem Cells and the Future of Medicine. "We always look for things at the edge, interesting and original things," says Hilary. "We're not talking about what other people have said, and certainly not talking about what philosophers like Aristotle said. It's all about now and things that are new, and we're always challenging consensus.

"A good example of that is the opening event, bang Goes the Big Bang, which will discuss the possibility that the idea might be a mistake and simply a tribal view that's become accepted. But there are a lot of problems with the theory. That's the sort of space that we want to inhabit and it obviously works."

One of the things the festival has done from the start is to keep venues small: "That creates an atmosphere where you are really close to speakers and performers, which is very different from what you'd get in a big hall. It's not great from a financial point of view but I think it's very important for the feel of the festival, allowing people to feel they can contribute to the debate.

"And we mix up speakers and performers, with no special spaces apart from a green room before events. Some of the best conversations happen in the coffee queue and that all adds to the sense of excitement.

"I think if you look at our programme it's pretty obvious that there's something there for everybody in terms of the subjects and conversations we have," says Hilary. "The Big Adventure is an event that demonstrates that. It's ab out romantic love and asks should we be pursuing it, is it a recent invention. Is it something that's not good for our lives, or is it maybe the best adventure?"

Details of the full festival programme can be found at howthelightgetsin.iai.tv