Duck test

You can help expand this article with text translated from the corresponding article in French. (September 2020) Click [show] for important translation instructions. View a machine-translated version of the French article. Machine translation, like DeepL or Google Translate, is a useful starting point for translations, but translators must revise errors as necessary and confirm that the translation is accurate, rather than simply copy-pasting machine-translated text into the English Wikipedia. Consider adding a topic to this template: there are already 1,586 articles in the main category, and specifying|topic= will aid in categorization. Do not translate text that appears unreliable or low-quality. If possible, verify the text with references provided in the foreign-language article. You must provide copyright attribution in the edit summary accompanying your translation by providing an interlanguage link to the source of your translation. A model attribution edit summary is Content in this edit is translated from the existing French Wikipedia article at [[:fr:Test du canard]]; see its history for attribution. You may also add the template {{Translated|fr|Test du canard}} to the talk page. For more guidance, see Wikipedia:Translation.

The duck test is a frequently cited colloquial example of abductive reasoning. Its usual expression is:

If it 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 identify an unknown subject by observing that subject's habitual characteristics. It is sometimes used to counter abstruse arguments that something might not be what it appears to be.