Duck test

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This looks like a duck, swims like a duck, and quacks like a duck. It is therefore probably a duck.

The duck test is a humorous term for a form of inductive reasoning. It can be explained this way:

If a bird looks like a duck, swims like a duck and quacks like a duck, then it probably is a duck.

The test implies that a person can figure out the true nature of an unknown subject by observing this subject's readily identifiable traits. It is sometimes used to counter abstruse arguments that something is not what it appears to be.

The duck test is common to the United States and the United Kingdom, where it is sometimes called the "British Standard (BS) Duck Test" in imitation of the system of national standards.^{[citation needed]}

[edit] History

It is unclear who coined the saying. Early references include:

• Richard Cardinal Cushing used the phrase in 1964 in reference to Fidel Castro.
• Richard Cunningham Patterson Jr., United States ambassador to Guatemala, during the Cold War in 1950, used the phrase when he accused the Jacobo Arbenz Guzmán government of being Communist.

Patterson explained his reasoning as follows:

"Suppose you see a bird walking around in a farm yard. This bird has no label that says 'duck'. But the bird certainly looks like a duck. Also, he goes to the pond and you notice that he swims like a duck. Then he opens his beak and quacks like a duck. Well, by this time you have probably reached the conclusion that the bird is a duck, whether he's wearing a label or not." (Immerman 1982, p. 102)

To Patterson and other United States officials, many traits of the Arbenz government showed that it was determined to implement revolutionary reforms. In their view, the Arbenz government's censorship of the dissident press, preference of state investment over private capital investment, agrarian reform, anti-imperialist measures, and democratic reforms (such as the legalization of labor unions) qualified it as communist.

The term duck test is still frequently used in the United States to describe the process of attributing the identity of an unknown based on its traits, especially in certain forms of computing.

The test is often used to identify something that is supposedly bad, and to justify the use of inductive logic in meting out punishment.

[edit] See also

• Duck typing
• Elephant test
• Identity of indiscernibles
• I know it when I see it
• Turing Test
• Zebra (medical)

[edit] References

• Immerman, Richard H. (1982), written at Austin, Texas, The CIA in Guatemala: The Foreign Policy of Intervention, University of Texas Press
• The complete works of James Whitcomb Riley; in ten volumes, including poems and prose sketches, many of which have not heretofore been published; an authentic biography, an elaborate index and numerous illustrations in color from paintings by Howard Chandler Christy and Ethel Franklin Betts
• Cushing of Boston: A Candid Portrait. by Joseph Denver - 1965