There are known knowns
|“||There are known knowns; there are things we know that we know.
There are known unknowns; that is to say, there are things that we now know we don't know.
But there are also unknown unknowns – there are things we do not know we don’t know.
The above statement was made by Rumsfeld on February 12, 2002 at a press briefing where he addressed the absence of evidence linking the government of Iraq with the supply of weapons of mass destruction to terrorist groups. It was criticised as an abuse of language by, among others, the Plain English Campaign. However, linguist Geoffrey Pullum disagreed, saying the quotation was "completely straightforward" and "impeccable, syntactically, semantically, logically, and rhetorically."
As for the substance of his statement, Rumsfeld's defenders have included Canadian columnist Mark Steyn, who called it "in fact a brilliant distillation of quite a complex matter", and Australian economist and blogger John Quiggin, who wrote, "Although the language may be tortured, the basic point is both valid and important ... Having defended Rumsfeld, I’d point out that the considerations he refers to provide the case for being very cautious in going to war." Moreover, one may criticize Rumsfeld's statement for omitting the most dangerous type of unknown: the "unknown known". That is, as Josh Billings famously expressed it, "It ain't what you don't know that gets you into trouble. It's what you think you know that just ain't so". Indeed, Rumsfeld was really discussing an "unknown known" which provided faulty justification for the war—members of the Bush administration claimed that the Iraqi government possessed weapons of mass destruction (see Rationale for the Iraq War), but it just wasn't so.
|“||A subject is certain of something when he knows that thing; he is uncertain when he does not know it, but he knows he does not: he is consciously uncertain. On the other hand, he is unaware of something when he does not know it, and he does not know he does not know [emphasis added], and so on ad infinitum: he does not perceive, does not have in mind, the object of knowledge. The opposite of unawareness is awareness.||”|
|“||If Rumsfeld thinks that the main dangers in the confrontation with Iraq were the "unknown unknowns," that is, the threats from Saddam whose nature we cannot even suspect, then the Abu Ghraib scandal shows that the main dangers lie in the "unknown knowns" – the disavowed beliefs, suppositions and obscene practices we pretend not to know about, even though they form the background of our public values.||”|
Žižek also builds the ideas of known unknowns, and unknown knowns, into a lecture on The Reality of the Virtual and a lecture on Architecture and aesthetics.
The term unknown unknowns was in use within the United States aerospace and military communities long before Rumsfeld's quote to the press in 2002. As early as 1969, Fortune magazine ran an article highlighting 'Unk-Unk' as an abbreviation used at Lockheed for 'unknown unknown'. An earlier use of the term in a military context comes from a 1984 paper about warfare:
|“||To those things Clausewitz wrote about uncertainty and chance, I would add a few comments on unknown unknowns – those things that a commander doesn't even know he doesn't know. Participants in a war game would describe an unknown unknown as unfair, beyond the ground rules of the game. But real war does not follow ground rules, and I would urge that games be "unfair" by introducing unknown unknowns.||”|
Around the same time, libertarian lawyer Richard Epstein wrote a well known article in the University of Chicago Law Review about the American labour law doctrine of employment at will (the idea that workers can be fired without warning or reason, unless their contract states otherwise). In giving some of his reasons in defense of the contract at will, he wrote this:
|“||The contract at will is also a sensible private adaptation to the problem of imperfect information over time. In sharp contrast to the purchase of standard goods, an inspection of the job before acceptance is far less likely to guarantee its quality thereafter. The future is not clearly known. More important, employees, like employers, know what they do not know. They are not faced with a bolt from the blue, with an "unknown unknown." Rather they face a known unknown for which they can plan. The at-will contract is an essential part of that planning because it allows both sides to take a wait-and-see attitude to their relationship so that new and more accurate choices can be made on the strength of improved information.||”|
The expression was used more recently, in 2005, in the context of risk and reliability:
|“||NASA space exploration should largely address a problem class in reliability and risk management stemming primarily from human error, system risk and multi-objective trade-off analysis, by conducting research into system complexity, risk characterization and modeling, and system reasoning. In general, in every mission we can distinguish risk in three possible ways: a) known-known, b) known-unknown, and c) unknown-unknown. It is probable, almost certain, that space exploration will partially experience similar known or unknown risks embedded in the Apollo missions, Shuttle or Station unless something alters how NASA will perceive and manage safety and reliability.||”|
In his 2007 book The Black Swan: The Impact of the Highly Improbable, Nassim Nicholas Taleb tells of a presentation on uncertainty he was requested to give to the United States Department of Defense shortly before Rumsfeld's speech. The core message of the Black Swan is that unknown unknowns are responsible for the greatest societal change.
Rumsfeld used the quote in the title of his autobiography Known and Unknown: A Memoir.
In popular culture 
Since Rumsfeld's speech, the full quote and the terms "known knowns" and "unknown unknowns" have appeared in popular culture:
- The title of The Unknown Knowns: A Novel by Jeffrey Rotter is an allusion to the quote, and the full quote appears in the book's inscription
- The quote is featured in the CD recording, The Poetry of Donald Rumsfeld and Other Fresh American Art Songs
- Hart Seely's compilation of quotes by Rumsfeld is entitled Pieces of Intelligence: The Existential Poetry of Donald H. Rumsfeld (2003)
- In The Boondocks animated series, the character Gin Rummy, a representation of Donald Rumsfeld, makes several references to unknown unknowns
- The band No Use for a Name used the entire aforementioned quote in their song Fields of Agony (Acoustic) on the record Rock Against Bush, Vol. 2
- In "Lil' George and Lil' Tony Blair", an episode of Lil' Bush, Lil' Rummy makes a reference to the unknown unknowns
- The Joan Jett song "Riddles" features the full unknown unknowns quote
- Belgian director Johan Grimonprez ends his film essay Double Take with the quote
- Theoretical physicist Lawrence Krauss uses the quote as opening to the second chapter of his book A Universe from Nothing
- In Zero Dark Thirty, the character Dan (played by Jason Clarke) utters the "unknown unknowns" part of the quote during an office meeting.
- Author Aaron Chynn, uses "unknown unknowns" as a basis for "How Knowledge Works" "There are those who think they know everything, these are the ones who don't know that they don't know everything...........etc"
See also 
- Dunning-Kruger effect
- I know that I know nothing
- Ignoramus et ignorabimus
- Ignotum per ignotius
- Johari window
- List of political catch phrases
- Ludic fallacy
- Outside Context Problem
- Relevance paradox
- Unknown known
- "Defense.gov News Transcript: DoD News Briefing – Secretary Rumsfeld and Gen. Myers, United States Department of Defense (defense.gov)".
- Steyn, Mark (December 9, 2003). "Rummy speaks the truth, not gobbledygook". Daily Telegraph. Retrieved 2008-10-30.
- Pullum, Geoffrey K. (2003-12-02). "Language Log: No foot in mouth". Penn: University of Pennsylvania. Retrieved 2012-04-12.
- Quiggin, John (February 10, 2004). "In Defense of Rumsfeld".
- "Rum remark wins Rumsfeld an award". BBC News. 2 December 2003. Retrieved March 31, 2013.
- Salvatore Modica; Aldo Rustichini (July 1994). "Awareness and partitional information structures". Theory and Decision 37 (1).
- "What Rumsfeld Doesn't Know That He Knows About Abu Ghraib". Retrieved 2009-02-23.
- "Dictionary definition of "unk-unk"". Retrieved 2012-07-11.
- Furlong, Raymond B., Lieutenant General, USAF (Ret.) (August 1984). "Clausewitz and Modern War Gaming: losing can be better than winning". Air & Space Power Journal, Air University Review Archive. Retrieved 2008-08-14.
- Epstein R (1984). "In defense of the contract at will". University of Chicago Law Review 51 (4): 947–975. doi:10.2307/1599554. JSTOR 1599554.
- Maluf DA, Gawdiak YO, Bell DG (3–6 January 2005). "On Space Exploration and Human Error: A paper on reliability and safety". Hawaii International Conference on Systems Science. Hilton Waikoloa Village, HI.
- "Northcom's new leader boosts focus on Mexico," http://www.washingtontimes.com/news/2010/jul/5/northcoms-new-leader-boosts-focus-on-mexico/print/
- "The Poetry of Donald Rumsfeld". stuffedpenguin.com. Retrieved 12 April 2012.