Some years ago, a friend, off to a debate on free speech, noted merely that he was set to discuss “yelling ‘fire’ in a crowded theatre”. The point being that, in such discussions, someone inevitably argues that this is one of the things free speech should not allow. Similarly, any consideration of the pros, cons or mere existence of the anti-war film will quickly get around to an indestructible quote from François Truffaut: “There’s no such thing as an anti-war film.” The French film-maker’s argument was that the persuasive tools of cinema – editing, acting, cinematography – cannot fail to...