As its subtitle suggests, one reason that Errol Morris's 2003 documentary The Fog of War: Eleven Lessons From the Life of Robert S. McNamara proved so resonant is that its subject was partly a proxy for his most notorious professional successor. "I don't do quagmires," Donald Rumsfeld said in a news briefing around that time, and there was the desperate sense that if life lessons could be learned from a chief architect of the Vietnam War, they sure as hell ought to be learned by a chief architect of the Iraq War. Rumsfeld is marginally more available now, and The Unknown Known is an unmistakably Morris-ish enterprise: built around a single-source interview, with the source looking straight into the camera and letting us try to get a read on him. It's too bad that Morris manages mostly just to extend the sport that Rumsfeld made of seeming callous — albeit absorbingly — at press conferences. Here again, Rumsfeld takes questions as if only for the challenge of riposting them with non-answers, either because he's unable or unwilling to assess the real consequences of his policy decisions in a meaningful way. Every time Morris seems to be handing over rope for Rummy to hang himself with, the smug bastard just ties it into a fancy Boy Scout knot. Of detainee abuse at Abu Ghraib and Guantánamo, he says, "I felt a very strong sense that something terrible had happened — on my watch." But quite unlike McNamara reflecting on Vietnam, he doesn't seem even a little bit broken up about it.