With certain ideas, you can predict commercial success. So with a Toy Story 3 or a Cars 2, you know the idea is more likely to have financial success. But if you go down that path too far, you become creatively bankrupt, because you're just trying to repeat yourself.
So we also want to do things that are unlikely, that are harder to solve. WALL-E, Ratatouille, and Up would all fail an elevator pitch. A rat that wants to cook does not sound like a commercial idea; you're not going to generate toys out of that. A man nearing the end of his life goes off with a young Scout in this balloon. Where does that lead? Are you going to sell toy walkers? With such ideas, you start out knowing there's a top to what you can get. So we try to strike a balance.
At some point, with either kind of film, the idea you started off with will not work. That's why I say that, at some point, all our movies suck—they really do. So on Ratatouille and Toy Story 2, we did a total restart. In both cases, we put a different director on it who delivered a brilliant piece of filmmaking.
Newt was another unlikely idea that wasn't working. When we gave it to somebody new [Pete Docter, director of Up], he said, "I'll do it, but I have another idea altogether, which I think is better." And we thought it was better too [Docter's concept was the basis of Inside Out, which he is directing for a 2015 release]. That was the reason we didn't continue with Newt.