Sources are conventionally categorized into three kinds: primary, secondary, and tertiary (think first-, second-, and third-hand). Their boundaries are fuzzy, but knowing these categories can help you conduct your research.
Consult Primary Sources for Evidence
Primary sources are “original” materials that provide you with the “raw” data or evidence you will use to develop, test, and ultimately justify your hypothesis or claim. In history, primary sources are artifacts or documents that come directly from the period you are studying: letters, diaries, objects, maps, even clothing. In literature or philosophy, your main primary sources are usually the texts you are analyzing, and your data are the words on the page. In the arts, your primary source would be the works of art you are interpreting. In social sciences, such as sociology or political science, census or survey data would also count as primary sources, as would data obtained through observation or experiment in many fields. The primary sources for those collected data are reports of original research in scholarly journals or government and commercial databases.
Read Secondary Sources to Learn from Other Researchers
Secondary sources are books, articles, papers, or reports that are based on primary sources and intended for scholarly or professional audiences. An article in a scholarly journal analyzing Alamo stories would be a secondary source for researchers working on those stories. The body of secondary sources in a field is sometimes called that field’s literature. The best secondary sources are books from reputable university presses and articles or reports that have been peer-reviewed, meaning that they were vetted by experts in the field before they were published. Secondary sources also include specialized encyclopedias and dictionaries that offer essays written by scholars in a field.
You use secondary sources for three purposes:
- 1. To keep up with current research. Researchers read secondary sources to keep up with the work of other researchers, to inform and refine their thinking, and to motivate their own work by adding to a published line of research.
- 2. To find other points of view. A research paper is not complete until the researcher acknowledges and responds to the views of others and to his readers’ predictable questions and disagreements. You can find most of those other points of view in secondary sources. What alternatives to your ideas do they offer? What evidence do they cite that you must acknowledge? Some new researchers think they weaken their case if they mention any view opposing their own. The opposite is the truth. When you acknowledge competing views, you show readers that you not only know those views but can confidently respond to them.
- 3. To find models for your own research and analysis. You can use secondary sources to find out not just what others have written about your topic but how they have written about it, as models for the form and style of your own paper. Imagine a secondary source as a colleague talking to you about your topic. As you respond, you’d want to sound like someone who knows the field, and so you’d try to learn how she reasons, the language she uses, the kinds of evidence she offers, and the kinds she rarely or never uses. The “conversation” would be in writing, so you’d even imitate stylistic details such as whether she writes in long paragraphs or breaks up her pages with subheads and bullet points (common in the social sciences, less common in the humanities).
You can also use a secondary source as a model for your conceptual analysis. If, for example, you were analyzing Alamo stories, you might study how a source treats Custer’s Last Stand. Is its approach psychological, social, historical, and political? Its particular reasons or evidence will probably be irrelevant to your project, but you might support your answer with the same kinds of data and reasoning, perhaps even following the same organization.
So if you come across a source that’s not exactly on your topic but treats one like it, skim it to see how that researcher thinks about his material and presents it. (You don’t have to cite that source if you use only its general logic, but you may cite it to give your own approach more authority.)
You can even borrow evidence from secondary sources to use in your own arguments, but you should do so only if you do not have access to the primary sources from which that evidence was originally taken. If you’re doing advanced work, check the accuracy of important quotations, facts, or numbers you draw from secondary sources.
Of course, if you were studying how the Alamo story has been analyzed, then secondary sources offering those analyses would be your primary sources.
If you’re new to a field, you may find secondary sources hard to read: they assume a lot of background knowledge, and many aren’t clearly written. If you’re working on a topic new to you, you might begin with an overview in a specialized encyclopedia or reliable tertiary source.
Read Tertiary Sources for Introductory Overviews
Tertiary sources are books and articles that synthesize secondary sources for general readers. They include textbooks, encyclopedias (including Wikipedia), and dictionaries, as well as articles in publications for broad audiences, like Time and the Atlantic. In the early stages of research, you can use tertiary sources to get a broad overview of your topic. But if you are making a scholarly argument, you should rely on secondary sources because these make up the conversation in which you are seeking to participate. If you cite tertiary sources in a scholarly argument, you will mark yourself as a novice or outsider, and many readers won’t take you—or your argument—seriously