Common knowledge is

knowledge Knowledge can be defined as awareness of facts or as practical skills, and may also refer to familiarity with objects or situations. Knowledge of facts, also called propositional knowledge, is often defined as true belief that is distinc ...

that is publicly known by everyone or nearly everyone, usually with reference to the

community A community is a social unit (a group of living things) with commonality such as place, norms, religion, values, customs, or identity. Communities may share a sense of place situated in a given geographical area (e.g. a country, village, tow ...

in which the knowledge is referenced. Common knowledge can be about a broad range of subjects, such as science,

literature Literature is any collection of written work, but it is also used more narrowly for writings specifically considered to be an art form, especially prose fiction, drama, and poetry. In recent centuries, the definition has expanded to include ...

, history, or

entertainment Entertainment is a form of activity that holds the attention and interest of an audience or gives pleasure and delight. It can be an idea or a task, but is more likely to be one of the activities or events that have developed over thousa ...

. Since individuals often have different knowledge bases, common knowledge can vary and may sometimes take large-scale studies to know for certain what is common knowledge amongst large groups of people. Often, common knowledge does not need to be cited. Common knowledge is distinct from

general knowledge General knowledge is information that has been accumulated over time through various mediums and sources. It excludes specialized learning that can only be obtained with extensive training and information confined to a single medium. General kn ...

. 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. Assigning something the label of common knowledge requires certain considerations about the involved community, group, society and/or individuals, the time period, the and the location.

Variation

Defining something as common knowledge can differ based on circumstances because there are variations in what is considered common knowledge amongst different groups. The variation can come from the time period, culture, population, class, age, demographic, and other circumstances. For example, The

Fifth Amendment to the United States Constitution The Fifth Amendment (Amendment V) to the United States Constitution addresses criminal procedure and other aspects of the Constitution. It was ratified, along with nine other articles, in 1791 as part of the Bill of Rights. The Fifth Amend ...

, 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.

Unstable

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 now common knowledge that the Earth revolves around the sun.

Large scale

On a larger global scale, it is not possible to define almost any knowledge as common knowledge because it is difficult know how far a fact has spread in global populations without large-scale global population studies. For example, the current president of the United States might be considered common knowledge in much of the world because of the power associated with that position, but one cannot assume that there is global recognition of this fact as common knowledge without further research into the knowledge of global populations.

Common belief

It is hard to define fact from belief and thus there are scholars who prefer to separate common knowledge from common belief. Common belief is something that is more easily defined because the requirement is only that a majority of people within a specific group, community, or society believe something to be true whereas common knowledge must meet this requirement and also prove that the belief is a fact.

Examples

* "

Paris Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. S ...

is the capital of

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

." Many capital cities of developed countries are considered common knowledge by most people, but one cannot claim this as common knowledge for global populations without further research. * "It is dangerous to mix

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous was ...

and

bleach Bleach is the generic name for any chemical product that is used industrially or domestically to remove color (whitening) from a fabric or fiber or to clean or to remove stains in a process called bleaching. It often refers specifically, to ...

." 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 amongst some American families and so could possibly be considered common knowledge in those populations, but may not extend to wider populations.

Other settings

Many techniques have been developed in response to the question of distinguishing truth from fact in matters that have become "common knowledge". Techniques for how to shape common knowledge can vary through professional settings.

Legal

In legal settings,

rules of evidence The law of evidence, also known as the rules of evidence, encompasses the rules and legal principles that govern the proof of facts in a legal proceeding. These rules determine what evidence must or must not be considered by the trier of fa ...

generally exclude

hearsay Hearsay evidence, in a legal forum, is testimony from an under-oath witness who is reciting an out-of-court statement, the content of which is being offered to prove the truth of the matter asserted. In most courts, hearsay evidence is inadmis ...

, which may draw on "facts" someone believes to be "common knowledge". The use of common knowledge in law varies between countries.

References

{{DEFAULTSORT:Common Knowledge Consensus reality Knowledge Social epistemology Consensus