But we don't ever get the result of our query - we never know the true answer to the problems facing society. So I don't think caching is a good metaphor. It's more like we just give up thinking because it's uncomfortable and it's easier to be like everybody else and make up our minds.
Our brains aren't designed to solve societal problems. Why should they be? They are designed to solve our own problems. The answers our brains give us are meant to benefit us. They may benefit society at large tangentially, but that is not the intent, nor should it be.
Please read Richard Dawkins' The Selfish Gene. Unlike his recent work, that one is really good.
Also: For ~5 minutes the reply button wasn't showing up. I guess PG coded in a little feature to make people take some time to calm down before getting into arguments. Beautiful.