Editing There are unknown unknowns (section)

==Origins==
Rumsfeld's statement brought attention to the concepts of known knowns, known unknowns, and unknown unknowns, but these were in common use in US defense procurement by the late 1960s.
In a 1968 study sponsored by the Aerospace Industries Association, Hudson Drake from North American Rockwell argued that defence contractors had to solve both known unknowns and "unanticipated unknowns".<ref>{{Cite book |title=History of Acquisition in the Department of Defence, Volume 2, Adapting to Flexible Response 1960-1968 |date=2013 |last=Poole |first=Walter S. |chapter=Chapter IV – Innovation: Coping with 'Unanticipated Unkowns' |page=95 |chapter-url=https://archive.org/details/adaptingtoflexib0002walt_i6x8/page/95/mode/1up}}</ref>
Also in 1968, Lt. Gen. William B. Bunker noted that when developing complex weapons systems "there are two kinds of technical problems: there are the known unknowns, and the unknown unknowns."<ref>{{Cite journal |title=The 'Known Unknowns' And The 'Unknown Unknowns' |journal=Armed Force Journal |date=1968-12-07 |last=Andrews |first=Walter| volume=106| issue=15|pages=14–15 |url=https://archive.org/details/sim_armed-forces-journal_1968-12-14_106_15}}</ref>
The usage was common enough for an industry shorthand to have developed where unknown-unknowns were referred to as "unk-unks".<ref>{{Cite journal |title=For Lockheed, Everything's Coming Up Unk-Unks |journal=Fortune |date=1969-08-01 |last=Meyers |first=Harald B. |volume=80 |issue=2| page=76}}</ref>

The term was commonly used inside [[NASA]].<ref>{{Cite web | url=https://books.google.com/books?id=dRMrAAAAMAAJ&q=%22unknown+unknowns%22&pg=PA73 |title = NASA Program Management and Procurement Procedures and Practices: Hearings Before the Subcommittee on Space Science and Applications of the Committee on Science and Technology, U.S. House of Representatives, Ninety-seventh Congress, First Session, June 24, 25, 1981 |year = 1981 |publisher=U.S. Government Printing Office}}</ref> Rumsfeld cited [[NASA administrator]] [[William Robert Graham|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.<ref name="Rumsfeld1">{{cite book|last1=Rumsfeld|first1=Donald|title=Known and Unknown: A Memoir|date=2011|publisher=Penguin Group|location=New York|isbn=9781101502495|page=xiv|url=https://books.google.com/books?id=_wIcpxMOjD4C&pg=PT15}}</ref>
Rumsfeld had previously publicly used the terms himself, stating in a 2000 speech that "There are known knowns, known unknowns and unknown unknowns.  Effective intelligence work must consider them all."<ref>{{cite book |first=Donald H. |last=Rumsfeld |title= Remarks of the Honorable Donald H. Rumsfeld Prepared for delivery, Community Forum Series: The New National Security Environment |location=Bryn Mawr, Pennsylvania |date=8 February 2000 |pages=194–203 |url=https://books.google.com/books?id=BZYZAAAAIAAJ&dq=%22unknown+unknowns%22+%22known+knowns%22+%22known+unknowns%22&pg=PA200 |series=Nominations Before the Senate Armed Services Committee, First Session, 107th Congress |publisher=U.S. Government Printing Office|isbn=978-0-16-069297-0 }}</ref>

The terms "known unknowns" and "unknown unknowns" are often used in [[project management]] and [[strategic planning]]<ref>{{Cite journal | url=https://hbr.org/1997/11/strategy-under-uncertainty | title=Strategy Under Uncertainty| journal=Harvard Business Review| date=November 1997| last1=Courtney| first1=Hugh| last2=Kirkland| first2=Jane| last3=Viguerie| first3=Patrick| volume=75| issue=6| pages=66–79| pmid=10174798}}</ref> circles.

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:

{{Blockquote|Site conditions always pose unknowns, or uncertainties, which may become known during construction or operation to the detriment of the facility and possibly lead to damage of the environment or endanger public health and safety. The risk posed by unknowns is somewhat dependent on the nature of the unknown relative to past experience. This has led me to classify unknowns into one of the following two types:

1. known unknowns (expected or foreseeable conditions), which can be reasonably anticipated but not quantified based on past experience as exemplified by case histories (in Appendix A) and

2. Unknown unknowns (unexpected or unforeseeable conditions), which pose a potentially greater risk simply because they cannot be anticipated based on past experience or investigation.

Known unknowns result from recognized but poorly understood phenomena. On the other hand, unknown unknowns are phenomena which cannot be expected because there has been no prior experience or theoretical basis for expecting the phenomena.<ref>{{cite book |url=http://www.empr.gov.bc.ca/Mining/Geoscience/PublicationsCatalogue/Papers/Pages/1980-7.aspx <!-- this maybe the document, see page 2 subtitle 'Phase V Waste Disposal' but seems not to cite actual 'Statement' --> |title=Statement of Evidence of E. D'Appolonia, D'Appolonia Consulting Engineers, Pittsburgh, Pennsylvania |series= Proceedings of the British Columbia Royal Commission of Inquiry into Uranium Mining |chapter=Phase V: Waste Disposal |year=1979 |id=0005037606 |isbn=978-0-7718-8198-5}}</ref>}}

The term also appeared in a 1982 ''[[The New Yorker|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.<ref>{{citation |last= Newhouse |first= J. |date= June 14, 1982 |title= A reporter at large: a sporty game; 1-betting the company |work= New Yorker |url=https://www.newyorker.com/magazine/1982/06/14/a-sporty-game-i-betting-the-company |pages= 48–105}}.</ref>