Plagiarism at its basic definition is using resources belonging to another person or organization without giving them due credit. However, it is a fact that almost everything around us was discovered earlier by someone else or is a result of another person’s ideas. There is hardly anything that isn’t the outcome of another person’s efforts. How do we know what should be given credit and what can be used without attribution? This is where ‘common knowledge’ comes into play.
The only source material that you can use in your academic work without attribution is common knowledge. This is because this cannot be attributable to a singular source. Common knowledge is information which is generally known to a peer or educated reader, such as popular facts and dates. However, facts and ideas that are definite outcomes of a certain individual's work cannot be considered as common knowledge and must always be cited. The Internet can be an easy source of information. It is possible that you mistakenly consider that what is available online is common knowledge. As a student, it can be tricky to decide whether something is common knowledge or not. The assumption that “everyone knows about this” is not reason enough for you to skip citations when you research online. The risk of not citing a source is greater than the result of citing something that is well known. Let’s look at some aspects of ‘common knowledge’.
Widely known scientific and historical facts are generally considered as common knowledge. Examples include who was the Emir of Qatar in 2000. This is widely known public information that is easily searchable if required.
Sometimes, the information can be common knowledge to a group of people. For example, the different blood groups are known among science students and the medical community. If you are mentioning this in your work, you are not expected to attribute this information to any source. However, should your discussion become more specific, and your inferences are drawn from another individual's work, research, or analysis, you must cite their work. For example, if you are going to discuss blood transfusions and there is a specific procedure you will be referring to - that is the result of another person’s research, then you must cite it.
As a general guidance, ideas or their interpretations are not usually considered as ‘common knowledge’, unless they are very well known. For example, if you are writing a paper communicating the vision of the state of Qatar, you will need to cite the Qatar General Secretariat for Development Planning even though it is common knowledge within the country.
The same treatment goes for opinions and perspectives shared on social media. You are not excluded from citing someone just because they are popular and their statements are known across their followers or are put out in the public domain. If you are not sure whether a quotation is common knowledge or not, take the safer route and cite it. Remember, common sense must be common practice.