I suspect that making people more rational would be one of the most efficient ways of saving the world. Things like AI might be better, but I really think it's pretty high up there as far as saving the world goes.

My reason for thinking that it'd make the world a much better place, is because making people more rational would lead to lots of better decisions and actions, which when aggregated, consist of a huge change. I've never really been able to articulate this well, but I think that this article illustrates part of what I mean: if people were more specific, they'd make better business decisions. Can't you imagine how all of these better business decisions would have a huge impact on the world? And can't you imagine how all of the other types of better decisions would also have a huge impact on the world?

I have 2 ideas about how to make people more rational. I'd love to get some feedback on them!
1) Popularize a medium for rational discussion. I'm not sure how I'd popularize it, but I suspect that it's doable.
2) Create a better system of education and make rationality a major part of the curriculum. 2a) I think that I could make this better system, prove that it's better by letting people use it for free and showing results, and that this will draw interest to it. 2b) I don't think there would be too much opposition to teaching rationality as part of the curriculum. 2c) I think learning about rationality can be fun. I think the material on Less Wrong could be made more accessible to the general population too.

(I recognize that 2) is a huge claim, and I suspect that I didn't think everything out properly, but I still think it has lots of promise.)