Primary and Secondary Sources: Home

A primary source is an original object or document from a specific time or event under study. Primary sources include historical and legal documents, interviews, eyewitness accounts, results of experiments, survey data, observations, diaries, paintings, works of literature, ancient pieces of pottery unearthed in Iraq, and much more . In the natural and social sciences, primary sources are often empirical studies — research where an experiment was done or a direct observation was made.

A secondary source is anything that’s written about a primary source, such as  an essay about a novel, a  newspaper article about AIDS research, a history textbook, a movie review, or subsequent thoughts on The Gettysburg Address.

Tertiary sources use primary and secondary courses to construct a narrative and/or theory. 

Can a single source ever be both?

Not really, but it can be confusing.  For instance, if I am writing a paper about global warming, a newspaper article that discusses new research on the topic issue is a secondary source.  But if I am writing a paper about the media’s coverage of global warming, then the newspaper article is a primary source.  What you are studying changes your relationship to the material. To further muddy the water, a secondary source may very well INCLUDE primary source materials in the form of pictures, statistics, or quotes, and that MIGHT work for your teacher, but it might not.  Likewise, to ensure accuracy, it is a good practice to track down the primary source if you can just to verify it.

Examples

This chart, created by librarians at the Indiana University Bloomington, illustrates kinds of primary and secondary sources by discipline:

The librarians at Princeton offer a good explanation of primary resources.

I think sometimes students view primary sources as “the real” sources, the ones that tell the truth and have not been adulterated by distance, time, or misrepresentation.  And there is some truth to that.  I often get e-mail forwards that say things like, “A new study by Harvard proves _________.”  The author of the email will often include a link to the study, and if you take the time to click on it and read it, you will often find that the original author of the forwarded email is either misunderstanding of misrepresenting what the ACTUAL study reveals.  So obviously in that case, you want the primary source. But finding the primary source has in some ways become trickier in the age of the internet, now that people can video something, heavily edit it, post it online (or on the news), and build a following and a narrative before the truth ever comes out. Consider this and this.  In the cases of Ed Schultz’s misrepresentation of George W. Bush and James O’Keefe’s misrepresentation of ACORN, what were taken as the primary sources were actually secondary sources–edited versions of the raw footage, so caveat emptor!

But keep in mind that there are other times when a secondary source is preferable.  Primary sources are always products of their times, and thus, a political speech from 1960 will not reflect an understanding of the present world, just as the Declaration of Independence won’t tell you who won the American Revolution, and an original research study about living with AIDS written in 1999 won’t explain the current best practices. Also, a distanced summary of a field that reflects all of its ups and downs and points and counterpoints is likely to give you a better understanding of the field than reading a single experiment or research paper. For instance, if you read Andrew Wakefield’s Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children, published in Lancet, 1998 (a primary source), you might find it persuasive in its indication that vaccines are linked to autism. However, reading a broader overview of the field, for instance a secondary source such as Good investigative reporting may finally debunk the myth that vaccines cause autism, published in Harvard Health Publications would reveal that the study was ultimately retracted by Lancet in 2010 because the research methods were flawed.

Being informed means more than finding the exact article that backs up your thesis; it means understanding how all the articles fit together within the broader structure and knowledge of the discipline. Information literacy demands attention to both primary and secondary sources as well as the critical thinking necessary to evaluate each for timeliness, credibility, and bias.