Common knowledgeisknowledge that is publicly known by everyone or nearly everyone, usually with reference to the community in which the knowledge is referenced.[1] Common knowledge can be about a broad range of subjects, such as science, literature, history, or entertainment. Since individuals often have different knowledge bases, it can be difficult to know for certain what is common knowledge amongst large groups of people.[2] Often, common knowledge does not need to be cited.[3] Common knowledge is distinct from general knowledge.
In broader terms, common knowledge is used to refer to information that an agent would accept as valid, such as information that multiple users may know.[2] As an example, this type of information may include the temperature in which water freezes or boils. To determine if information should be considered common knowledge, you can ask yourself who your audience is, are you able to assume they already have some familiarity with the topic, or will the information's credibility come into question.
Many techniques have been developed in response to the question of distinguishing truth from fact in matters that have become "common knowledge". The scientific method is usually applied in cases involving phenomena associated with astronomy, mathematics, physics, and the general laws of nature. In legal settings, rules of evidence generally exclude hearsay (which may draw on "facts" someone believes to be "common knowledge").
"Conventional wisdom" is a similar term also referring to ostensibly pervasive knowledge or analysis.
Difficulty establishing common knowledge
It can be difficult to define something as common knowledge because there are variations in what is considered common knowledge amongst different groups.[3] For example, The Fifth Amendment to the United States Constitution, might be considered common knowledge amongst people residing in the United States of a certain age, but cannot be considered common knowledge when considering the general population of other countries.
Another issue that must be considered is that of the time period. Common knowledge is not always stable, and can shift over time to create new common knowledge. Knowledge that was once considered common knowledge amongst a group, society, or community might later become known as false. For example, for centuries it was common knowledge in Europe that the sun revolved around the Earth, but after years of arguments, it is not common knowledge that the Earth revolves around the sun. [4]
Examples
Examples of common knowledge:
"Paris is the capital of France." Many capital cities of countries are considered common knowledge by most people.
"The Moon orbits the Earth." Observation of the moon shows us that this happens. In addition, scientific findings give confirmation. At various periods in history, it was regarded as common knowledge that the Earth is flat and that the Sun orbits the Earth, although these theories were later found to be false.
"It is dangerous to mix ammonia and bleach." Though both common household chemicals, accidents involving the mixing of ammonia and bleach are rare, because the potentially lethal danger in their chemical reaction is a widely circulated cautionary tale.
"The Fifth Amendment to the United States Constitution grants American citizens the right to refuse to answer any question in a court of law that would engender incriminating themselves." "Pleading the Fifth" is a phrase commonly used in American colloquial speak, and even in such popular media as the sketch comedy series Chappelle's Show. Thus it may be regarded as common knowledge in the United States.
J-J Ch. Meyer and W van der Hoek Epistemic Logic for Computer Science and Artificial Intelligence, volume 41, Cambridge Tracts in Theoretical Computer Science, Cambridge University Press, 1995. ISBN0-521-46014-X
Stalnaker, Robert. "Assertion". Pages 315–322 in P. Cole (ed.). Syntax and Semantics9: Pragmatics, 1978.
