Primary vs. Secondary Sources
The terms “primary” and “secondary” are used to describe the metaphorical distance between a source and the event that it describes. For example, the diary of a participant in the Boston Tea Party would be considered primary while a book about that event by a modern researcher would be considered secondary.
But the devil is in the details. First, we must remember that these terms are relative. In the above example, the modern book is secondary relative to the Boston Tea Party. If we were instead writing a paper on the life of the book’s author, it would be primary. Thus, one can’t definitively say that a given source is innately primary or secondary—it always depends on the subject of your research.
Second, the application of these terms differs by discipline. A historian would consider almost any scholarly publication to be a secondary source relative to the event that it describes. In the sciences, a scholarly paper written describing results obtained by the authors of that paper is considered primary.
As you might imagine given these caveats, not everyone will agree on the question of whether a given source is primary or secondary for the purposes of your paper. So, if your instructor asks you to use primary sources for your paper, it is best to ask exactly what they mean. They may or may not agree with the library’s use of these terms.
Finally, remember that primary sources are not necessarily better than secondary sources. For instance, a later, scholarly work about a historical event can provide a degree of context that could not be expected of a participant in that event. Proximity to an event ensures neither accuracy nor objectivity. You will probably want to use a mix of primary and secondary sources in your research.
Humanities
Primary sources in the humanities can be many things. They’re often referred to as “firsthand accounts,” but that definition includes more than you might think. A diary or letter from a historical figure might be a primary source, although within that there is some complexity. Just being from the same time as an event doesn’t make an account firsthand; the proximity of the writer to the event is key, and the question you’re answering matters. In some cases, historical newspapers will count as primary sources, but in other cases they are considered secondary. Primary sources aren’t limited to text—paintings, sculptures, photographs, and other artifacts can be primary sources.
Say you’re writing a paper on the influence of Monet on the music of Debussy and Ravel.
Primary
- Monet’s painting Impression, soleil levant (1872)
- The score of Debussy’s La Mer
Secondary
- Exhibition catalog from a Monet exhibit
- Biography of Debussy
- Scholarly article about Monet’s cultural influence
Natural Sciences
In the natural sciences, the phrase “primary sources” means something very different—it will refer to original research. If you’re asked to find a primary source in chemistry, for example, look for a paper in which the author has done an actual experiment and presents the results. Those articles are considered primary, as opposed to “review articles,” which summarize the results of others’ research but don’t include original experimentation.
Let’s say you’re researching the environmental impact of the use of a particular pesticide in agriculture.
Primary
- A scholarly paper written by a team of scientists who measured the number of nematodes in experimental plots at varying distances from a site where the pesticide was applied
- The original data that the scientists collected
Secondary
- A newspaper article that reports on the scientists’ work
- A review article on pesticide research
Social Sciences
In general, primary sources contain firsthand information. In the social sciences, that covers a broad range. Depending on your research, that might include data/statistics, audiovisual materials, interviews, newspaper articles, reports, and social media posts. As long as they are original, they may count as a primary source. If you’re not sure whether your source is primary, check with a librarian or your instructor.
For example, you're writing a paper about Apple’s advertising strategy.
Primary
- Sales data provided by Apple
- Instagram posts from Apple’s official account
- A video of a talk by Apple’s CEO
Secondary
- An article in AdWeek about a recent Apple ad campaign
- A Harvard Business Review case study