Definition

Noun: Information or facts that are known by most people within a particular society or group. It refers to something so widely recognized that it is accepted without the need for proof or citation.

Usage

"Common knowledge" is used to describe information that is publicly and widely known. It is often invoked to indicate that something does not require explanation, verification, or a specific source in general conversation or argument.

Examples

• It is common knowledge that the Earth revolves around the Sun.
• Before the internet, local news spread by word of mouth and became common knowledge in the town.
• You don't need to cite a source for that fact; it's considered common knowledge.

Advanced Usage

• Legal Context: In law, especially in defamation cases, a "common knowledge" defense may be used, arguing that the allegedly harmful information was already publicly known.
• Epistemology: In philosophy, "common knowledge" refers not just to everyone knowing something, but to everyone knowing that everyone knows it, and everyone knowing that everyone knows that everyone knows it, and so on. This concept is crucial in game theory and reasoning about social situations.

Variants and Related Words

• Commonly known (adj. phrase): A simpler adjectival phrase with a similar meaning.
  • It is a commonly known fact.
• General knowledge (n.): Often used interchangeably, though it can sometimes imply a body of learned information (like trivia) rather than universally accepted facts.
• Public domain (n.): In intellectual property, this refers to works not protected by copyright, but it can be used metaphorically to mean ideas or information freely available to everyone.

Synonyms

• General awareness
• Public knowledge
• Widely known fact
• Established fact

Antonyms

• Secret
• Esoteric knowledge
• Confidential information
• Specialized/Expert knowledge

Idioms and Phrases

• To be (just) common knowledge: Emphasizes the public nature of the information.
  • His resignation isn't a secret; it's just common knowledge around the office.
• Pass into common knowledge: Describes the process by which information becomes widely accepted.
  • Over the decades, the theory passed into common knowledge.

Noun

1. anything generally known to everyone