Common knowledge is information that is widely known within a society or an intellectual community; therefore, if you include common knowledge in your paper, you do not need to cite where you found that information.
Answer Yes or No to the following questions:
- In a high school class on American government, you learned about the checks-and-balances system of government, which separates power into the Judicial, Executive, and Legislative branches. Now, you are writing a paper for an introductory political science class and you mention the concept of checks-and-balances you learned in high school. Should you cite your old high school textbook?
- In writing a paper about pop culture in the 1980s, you want to include the year that Reagan was shot but you cannot remember if it was 1980 or 1981, so you look up the correct date in an encyclopedia. Do you have to include that encyclopedia as a source for the date on which Reagan was shot?
- You do most of your research online and find lots of interesting websites, from which you quote several passages. After you write the first draft, you ask your older and more experienced room-mate if he knows how to cite websites. He says that websites are in the public domain and constitute common knowledge, therefore they do not need to be cited. Is this true?
- In writing a research paper on astrophysics, you come across something called the Eridanus Effect several times. You have never heard of this effect nor discussed it in your class, but after reading about it in six different astrophysics journal articles, you have a pretty clear idea of what it is and its most common characteristics. Is the Eridanus Effect common knowledge within astrophysics?
- Your older sister has a job working for a non-profit organization that runs adult literacy programs in factories and unemployment centers in several major cities. Over winter break, she tells you about the success of one of the programs in St. Louis and the innovative curricula it has designed. Several weeks into spring semester, you remember your conversation as you are writing an economics term paper on empowerment zones and unemployment in the inner city. If you include a description of the program, do you need to cite a source, even if it is just your sister?
- You are writing a paper on Shakespeare's Hamlet. Your textbook's introduction to the play mentions that Shakespeare was born in 1564 in Stratford-upon-Avon. You mention these facts in your paper's introduction. Do you need to cite the introduction to your textbook?
- You are writing a paper on Shakespeare's Hamlet. A footnote in your textbook mentions that some literary historians now believe that Shakespeare himself played the ghost when the play was first performed. If you mention Shakespeare playing the ghost, do you need to cite this footnote in your textbook?
- You are writing a paper on the assassination of Robert Kennedy. The three major biographies on him mention when he was killed and by whom. Do you have to cite all these biographies when you mention the date and murderer of RFK?
- You are writing a paper on the assassination of Robert Kennedy. The most influential biography on him mentions a controversial conspiracy theory first put forward in the early 1970s by a journalist for the Washington Post. When you mention this conspiracy theory, should you cite the biography?