Assume a can opener

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"Assume a can opener" is a catchphrase used to mock economists and other theorists who base their conclusions on impractical or unlikely assumptions. The phrase "takes aim at how economists use assumptions to simplify—and sometimes oversimplify—the problems they face".[1] It may be used to express the writer's disdain for "the propensity of modern economic theory for unjustified and oversimplified assumptions."[2]


It derives from a joke which dates to at least 1970 and possibly originated with British economists.[3] The first book mentioning it is likely Economics as a Science (1970) by Kenneth E. Boulding:[4]

There is a story that has been going around about a physicist, a chemist, and an economist who were stranded on a desert island with no implements and a can of food. The physicist and the chemist each devised an ingenious mechanism for getting the can open; the economist merely said, "Assume we have a can opener"!

The phrase was popularized in a 1981 book and has become sufficiently well known that many writers on economic topics use it as a catchphrase without further explanation.[5][6]

Examples of usage[edit]

The joke and its application to economists were taken up in the 1981 book Paper Money by "Adam Smith" (pseudonym of George Goodman),[7] wherein he applied the story to the then-tendency of economists to assume that inflation would go away, and mocked the notion that economists are "the high priests of this esoteric mystery."[8] In contrast, he asks "why the economists are always wrong."[9] The phrase "assume a can opener" became "his nagging accusation against the deductive logic and analytical models of economists."[10]

The Italian finance minister Tommaso Padoa-Schioppa used the phrase in 2006 to illustrate that "Very often, when economists comment, they assume politics away."[11] It has been used in Australia to describe "a treasurer who has lost all touch with reality"[12] and politicians "assuming away" the problem of getting a global greenhouse gas deal.[13] It was used in India to describe American economic policy toward China.[14]

It has been extended beyond economics to describe diplomats and negotiators working toward peace in the Middle East, who have "attempted to build confidence among the warring parties as if the conflict were just a big misunderstanding" and who "assumed leaders who did not exist, as a way to conjure a preferable reality."[15]

See also[edit]

  • Occam's razor – Philosophical principle of selecting the solution with the fewest assumptions
  • Spherical cow – A humorous metaphor for highly simplified scientific models of complex real life phenomena


  1. ^ Mankiw, N. Gregory (2010). Macroeconomics (7th ed.). New York: Worth Publishers. pp. 238–239. ISBN 1-4292-1887-8.
  2. ^ Kaletsky, Anatole (2010). "11 "There is no can opener"". Capitalism 4.0: The Birth of a New Economy in the Aftermath of Crisis. New York: Public Affairs, a member of the Perseus Books Group. p. 156. ISBN 978-1-58648-871-0.
  3. ^ Barry Popik: “Assume you have a can opener” (economics joke about opening a food can). In: The Big Apple. December 5, 2010
  4. ^ Kenneth E. Boulding: Economics as a Science. McGraw-Hill, 1970, p. 101
  5. ^ Drum, Kevin (August 18, 2010). "First, Assume a Can Opener..." Mother Jones. Retrieved 18 March 2013.
  6. ^ "Monetary policy: First, assume a can-opener". The Economist. November 28, 2012. Retrieved 18 March 2013.
  7. ^ Silk, Leonard (March 22, 1981). "Bullish about the system". The New York Times. Retrieved March 18, 2013.
  8. ^ "Straight talk given on economic mess". Daily Times. March 28, 1981. Retrieved 18 March 2013.
  9. ^ Lehmann-Haupt, Christopher (March 9, 1981). "Books of the Times: Review of Paper Money by Adam Smith". The New York Times. Retrieved 18 March 2013.
  10. ^ Silk, Leonard (March 22, 1981). "Bullish about the system". The New York Times. Retrieved 18 March 2013.
  11. ^ Norris, Floyd (November 24, 2006). "High and low finance: Temptations of a minister of finance". The New York Times. Retrieved 18 March 2013.
  12. ^ McCrann, Terry; Herald-Sun (June 8, 2011). "Swan's speech a laugh a minute". Herald Sun. Retrieved 18 March 2013.
  13. ^ Carmody, Geoff (March 2, 2011). "Doing nothing is preferable to this". The Australian. Retrieved 18 March 2013.
  14. ^ Kemp, John (April 5, 2011). "Easy money will keep pressure on commodities". Reuters India. Retrieved 18 March 2013.
  15. ^ May, Cliff (February 17, 2009). "Peace Processing 101". Gettysburg Times. Retrieved 18 March 2013.