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Common Knowledge

Not all ideas require attribution, specifically, facts that are common knowledge. Common knowledge exists when a fact can be found in numerous places or is likely to be known by a lot of people. For example, you do not need to document the fact that Abraham Lincoln was the 16th President of the United States since this information is widely known. On the other hand, you must credit your source for facts that are not generally known or ideas that interpret facts. For example, Lincolnís tall and gangly stature is consistent with symptoms of Marfan syndrome (Davidson, 2004

Information from reference sources such as encyclopedias, dictionaries, almanacs, etc. often does not need to be cited. This is because the purpose of reference sources is usually to collect together common knowledge on a subject. However, not citing reference sources is at best a loose rule of thumb. Whether a reference source needs to be cited depends more on the nature of the information than the type of source. It also depends on the studentís reason for citing the information. For example, if you wish to establish authority for the information, then you need to cite the source: Physicians consider abnormal elongation of the long bones to be a primary characteristic of Marfanís syndrome (Merriam Webster)However, if you are merely trying to inform your reader of something that is common knowledge in a field, then it is not necessary to cite the source: One of the main characteristics of Marfanís syndrome is abnormal elongation of the long bones.

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Davidson, Glen W. (2004) Abraham Lincoln and the DNA controversy. Retrieved February 5, 2008, from  http://www.historycooperative.org/journals/jala/17.1/davidson.html

Merriam Websterís medical dictionary. (2007-2008). Retrieved February 5, 2008, from http://medical.merriam-webster.com/medical/marfan


Last updated 10/22/2008 by Sue Thompson, Toni Olivas
Cal State San Marcos Library