Guardian: Al Gore’s An Inconvenient Truth was a quietly persuasive documentary on global warming that probably made many converts. The Age of Stupid, starting with its in-your-face title, is what might be called “a hecture”, a hectoring lecture on the same subject which, like a hell-fire sermon, might go beyond fire and brimstone and dismiss the very thought of hell altogether. The movie has a semi-fictional framework with a future archivist, played by Pete Postlethwaite, sitting in a giant concrete …