The Unknown Known

"It's a failure of imagination. It's important to have priorities," says former US Secretary of Defense Donald Rumsfeld and we see his memo on strategic thought from September 30, 2001 on the screen. Errol Morris in The Unknown Known touches on issue after issue, in customary form. "If you wish for peace, prepare for war" is followed by "all generalisations are false, including this one."

Morris presents Rumsfeld in the classic format. No illustrations illuminate us about what we don't know, or rather the unknown known which is the title of the documentary and refers to the omitted fourth option to a question from 2001 about America's worries. A vault of filing cabinets, storing decades of Rumsfeld memos, is the entryway into the maze of American politics.

We move back to 1962 when Rumsfeld was elected, see him with Nixon, and get a bit of private life. "How did you propose?" provokes Rumsfeld to state about his marriage that "I was correct. It was a good decision." It sounds impassive and there, as on all fronts of the film, you might wonder what an unofficial version might look like. In November 1975, he became the youngest Secretary of Defense in history.

He refers to his meeting with Saddam Hussein in 1983 and comments how he was living an image of himself which was pretend. The camera stays on Rumsfeld's talking head, just a few seconds longer to hint that he himself might be doing the same. Well, who isn't and what wisdom exactly is there in the first place?

"I see the glow in your eyes," Rumsfeld comments to Morris (off camera) who just asked him about his "obsession".

"I am cool," the former Secretary of Defense counters, "it's not an obsession, but a measured, nuanced approach."

Rumsfeld recounts his personal 9/11 experience, from thinking it was an accident to feeling the Pentagon shake. Rumsfeld answers politely about Saddam Hussein, weapons of mass destruction, Richard Nixon, and his own former assistant Dick Cheney. He grins about his relationship with President Bush the elder, and while he discusses the "torture memos", a children's choir sings on the soundtrack.

We learn how often Rumsfeld asked to consult the Pentagon Dictionary. Terminology matters, especially when "unconventional warfare" or "terrorism" are in question. Ultimately, the Unknown Known is what you don't know you know. This film is a reminder.

"The absence of evidence is not evidence of absence" and "stuff happens" are well remembered quotes and show up in the documentary like best-of highlights. Expected and delivered. His letter of resignation in reaction to the detainee issue , "something terrible happened on my watch" - prompts the filmmaker to ask if it hadn't been better not to go there at all. "Time will tell," is his response.