There are known knowns

"There are known knowns" is a phrase from a response United States Secretary of Defense Donald Rumsfeld gave to a question at a U.S. Department of Defense (DoD) news briefing on February 12, 2002, about the lack of evidence linking the government of Iraq with the supply of weapons of mass destruction to terrorist groups.
Rumsfeld stated:
The statement became the subject of much commentary including a documentary film, "The Unknown Known", directed by Errol Morris.
Origins.
Rumsfeld's statement brought much fame and public attention to the concepts of known knowns, known unknowns, and unknown unknowns, but national security and intelligence professionals have long used an analysis technique referred to as the Johari window. The idea of unknown unknowns was created in 1955 by two American psychologists, Joseph Luft (1916–2014) and Harrington Ingham (1916–1995) in their development of the Johari window. They used it as a technique to help people better understand their relationship with themselves as well as others.
The term was also commonly used inside NASA. Rumsfeld cited NASA administrator William Graham in his memoir; he wrote that he had first heard "a variant of the phrase" from Graham when they served together on the Commission to Assess the Ballistic Missile Threat to the United States during the late 1990s. Kirk Borne, an astrophysicist who was employed as a data scientist at NASA Goddard Space Flight Center at the time, noted in an April 2013 TED talk that he had used the phrase "unknown unknowns" in a talk to personnel at the Homeland Security Transition Planning Office a few days prior to Rumsfeld's remarks, and speculated that the term may have percolated up to Rumsfeld and other high-ranking officials in the defense department.
The terms "known unknowns" and "unknown unknowns" are often used in project management and strategic planning circles.
Known unknowns refers to "risks you are aware of, such as canceled flights ..."
Unknown unknowns are risks that come from situations that are so unexpected that they would not be considered. Contemporary usage is largely consistent with the earliest known usages. For example, the term was used in evidence given to the British Columbia Royal Commission of Inquiry into Uranium Mining in 1979:
The term also appeared in a 1982 "New Yorker" article on the aerospace industry, which cites the example of metal fatigue, the cause of crashes in de Havilland Comet airliners in the 1950s.
Reaction.
While the remarks initially led to some ridicule towards the Bush administration in general and Rumsfeld in particular, the consensus regarding it has shifted over the years, and it now enjoys some level of respect. For example, 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."
Psychoanalytic philosopher Slavoj Žižek says that beyond these three categories there is a fourth, the unknown known, that which one intentionally refuses to acknowledge that one knows: "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.". Related to this is the concept of tacit knowledge, knowledge which we may act on, but not be aware of or able to articulate.
German sociologists Daase and Kessler (2007) agree with a basic point of Rumsfeld in stating that the cognitive frame for political practice may be determined by the relationship between "what we know, what we do not know, what we cannot know", but Rumsfeld left out "what we do not like to know".
The event has been used in multiple books to discuss risk assessment.
Rumsfeld named his autobiography "". In an "Author's Note" at the start of the book, he expressly acknowledged the source of his memoir's title and mentioned a few examples of his statement's prominence, including a Wikipedia article. "The Unknown Known" is the title of Errol Morris's 2013 biographical documentary film about Rumsfeld.
In addition, the comment earned a Foot in Mouth Award.
Analytical sciences.
The term "known unknowns" has been applied to the identification of chemical substances using analytical chemistry approaches, specifically mass spectrometry. In many cases, an unknown to an investigator that is detected in an experiment is actually known in the chemical literature, a reference database, or an Internet resource. These types of compounds are termed "known unknowns". The term was originally coined by Little et al. and reported a number of times in the literature since then as a general approach.