In M. Night Shyamalan's film Signs, the protagonist suffers a crisis of faith so deep that it takes an alien invasion of Earth for him to work it out.

In Shyamalan's latest movie, The Happening, the protagonist suffers a crisis of reason. Unfortunately, this time not even the looming extinction of humanity resolves it for him.

Given that it's mass entertainment, the film raises a lot of interesting questions about science, and it's clear from it that Shyamalan's interest in science goes much deeper than a superficial mining of ideas for plot lines.

His protagonist, high school biology teacher Elliot Moore (played by Mark Wahlberg), lectures about the limits of science's ability to explain the world and applies his critical faculties to staying alive when the "happening" happens.

He deduces that trees and grasses, stressed by human presence, emit a toxic substance that causes progressively smaller clusters of people - first cities, then towns and villages, then groups of refugees, and finally lone individuals - to commit suicide.

Meanwhile, his friend Julian (John Leguizamo), a math teacher, comes to terms with imminent death by teaching one last student the parable of rice grains on a chessboard.

To the wider world, it remains unclear whether the attack was a terrorist incident, a bioweapons experiment gone awry, a nuclear accident or another of the usual suspects, and the film ends with humanity still missing the environmentalist message - at its peril.

George Musser interviewed Shyamalan by phone earlier this week.

One of the things I wanted to ask you about were your thoughts about the limits of science. That's clearly something on your mind; it comes out in the very beginning of the film and toward the end of the film as well.

The thing is, we have only our own invented categories in which to judge things. This thing that we're looking at, which of our eight categories (or however many) does it fit in?

The things that don't quite fit in, we shove into something. We're inventing those categories; it's very limited.

Psychologically, if you're looking for something in your data, you'll see it. If you're doing an experiment and you're looking for patterns, and you go: "Oh, there it is! I see it!"

In that same way, if you're going, "There's always an explanation that we have already at our fingertips," you're going to find some way to put it in there.

But there's so much unexplained stuff. I don't quite understand the scientific explanation of the placebo effect.

What is the core of that? The fact that the placebo effect exists is a fact, but what is it? We have no idea. I love that. I even love that with regard to the home-court advantage in sports.

What is that? It's connected to a belief system. Both things, the placebo and the home-court effect, are a belief system that we can turn thought into actual biological function.

In and of itself, that's something that science says is not possible. But you can document it.

Most people, if you just stop them on the street, would say that science has always got the answers to things.

But if you stop most scientists in their laboratories, they would say the exact opposite: how little they know about the world.

Science as an act of humility. And I think you had Elliot say something very similar to that.

Right.

Do you see some of these "acts of nature" - in the film you brought up red tide and colony collapse - as forever beyond our capacity to explain? Or is it something that, with enough thought and enough effort, we can explain?

It'll either get thrown into some tentative, tenuous explanation or it'll be thrown into the pile of the placebo effect: "OK, it's fact, but we have no idea."

There's another one: When the tsunami came, the animals all ran, sensing it happening.

What is it that's in their primitive - we'll call it "primitive" - biological makeup, that we've forgotten? It would seem that would be quite an asset for a species to have what they have - knowing something's wrong and we better get out of here.

We don't have that, and yet we're supposed to be higher-functioning. So what happened?

We don't even understand that. What is it about the intuitiveness of animals? Is it some microscopic shift in the atmosphere that they're sensing? What is it, exactly?

There's so many of those amazing things that tie us to each other, that make us all one system.

The basic thing about the movie is that we're pretending we're not part of the system. You said you had drawn inspiration from Einstein's recent biography, the Isaacson biography.

It's the same type of thing. I get that feeling of what drives you to say that there's an answer: the beauty of simplicity.

What is the beauty of simplicity? That is, there's something that binds everything. To keep looking for that, that drive is almost the holy grail.

I can totally relate to that on an intuitive level. That's somehow tied to some mystical thing I don't know if "mystical" is the correct word.

It's beyond logic; it's the evidence that all things come from one simple thing.

Obviously, a lot of people as they come away from the film, or as it will be depicted in the press, will talk about the environmental aspects.

Clearly, the whole plot revolves around that. But I wanted to ask you from a deeper level - that there's this breakdown of the survival instinct.

We do things that are not in our own survival interests. There's the classic example of someone smoking in an organic food restaurant.

There's also our attitudes toward risk, and that comes out in how the government is not approaching global warming, for example.

That's true. You could give mitigating factors for each of those. The survival instinct is somehow ingrained in us.

Maybe there's a gut version of that and an intellectual version of that, and the intellectual version of it fails us all the time. So we smoke in an organic food restaurant. It just fails us.

A lot of our instincts have flipped. It's not like we're running out to go hunt deer down for the dinner; we have it readily available. So the body's instinct to store carbs is now turning against us, and so everybody's obese.

But you can't turn it off. You can't go, "We're always going to have food, stop triggering that thing!" You just crave and crave.

That's why everybody's kids are always, like, "How come we always want to eat the bad things? Why can't we want the vegetables, and not the carbs?"

The body's doing that from an old, old habit of trying to store as much fat as possible.

When I was thinking about what could you do to the human species if you were fed up with it, it's a very basic thing of the survival instinct gets turned off.

There's this natural backlash against humanity in the film. Of course, in reality, there's always a type of a backlash.

Life is much more precarious than we sometimes give it credit for. Civilisation is more precarious. Was that also kicking around in your mind?

Right now, I'm on the highway in Manhattan, and there's a million of us, and it all seems very important, where we're going.

There's some trees lining this road that we're on here, the West Side Highway. But really the moment that you feel accurate, with regard to our importance in the world, is when you're out in the ocean and you get a little too far out.

You're floating out there and you get a little bit of a pang and then you look around and it's so far out.

You thought you were in the same place, but the ocean has pulled you another 50 yards out. And you're out there, and you feel vulnerable.

Those are the tiniest moments in your life that you actually feel the correct relationship with nature, as when people are in a giant storm. At those moments, it is precarious.

Those are the moments when we go back to the Native American point of view of nature: "Oh yeah, you remember those silly, simple folk? They're right!"

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