An oxymoron if I ever heard one. To become rational means letting go of fears (to a large extent). I fear that one reason we fail to act is that we are guided by fear. Fear makes us focus on the wrong things. And I fear that in a civilized society fear becomes a self fulfilling prophecy. Fear makes us obsess about the problem and how to avoid it in the very narrow and short term. It doesn't make us very good at long term planning and execution. It's an instinct that is evolved for animals that want to avoid predators, not for civilization builders.
Building a civilization requires vision, big plans and the feeling that we can afford bold ideas. We need to take risks. But how can we take more risks when we're constantly afraid of the future? How can we build a better future when all we do all day is imagining the worst possible future? If our minds are constantly occupied by dystopia we can't plan for anything else. So that's what we build.