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Philosophy: Primary, Secondary & Tertiary Sources

Resources for the study of philosophy.

Primary, Secondary & Tertiary Resources

Sources are considered primary, secondary, or tertiary depending on the originality of the information presented and their proximity or how close they are to the source of information. This distinction can differ between subjects and disciplines and the boundaries between these categories are sometimes fuzzy and may differ from discipline to discipline.

Furthermore, the primary, secondary, and tertiary distinctions are subjective and contextual, with the categorization of any single information source often shifting according to the context in which it is being used or studied. Regardless, a basic understanding of these three categories of information sources will be useful as you outline your research process.


Review the info about for your source.

What type of information source are you viewing? (peer-reviewed article, original text/literature, news/current events, website, scholarly but not peer reviewed resource, etc.)

What is being reported in each source? How would you classify (primary, secondary or tertiary) each source?

Primary Sources in Philosophy and other disciplines

Primary Sources

What qualifies as a primary source varies from discipline to discipline, but a primary source will always be "original," "new," or "close to the source/event/period" in some way. Primary sources are characterized by the information they convey and their relationship to the research question in that they have not been filtered through interpretation or evaluation. Rather, the interpretation and evaluation of primary sources serves as the basis for other research, often analyzed through secondary and summarized in tertiary sources.

Primary Sources include:

  • In literature and philosophy the primary document is the text you are consulting or writing about; a primary source is usually a major—or a group of major—philosophical texts.
  • In history, documents from the period under study or written by someone who experienced or witnessed the event or period under study are considered primary sources; diaries, journals, letters, speeches, interviews, and newspaper articles from the period may qualify as primary sources, as can memoirs and interviews written at a later date, so long as the author/interviewee experienced the period or event under study.
  • In the sciences, a primary source is the original publication of a scientist's research (data, research/study results, theories, etc...).
  • In the history of ideas or intellectual theory, the primary sources are the documents (books, essays, articles, letters) written by scholars, experts, intellectuals, or theorists.  
  • In anthropology, physical objects - photographs, jewelry, weapons, coins, paintings or buildings - are often considered to be primary sources.
  • Works of art serve as the primary sources in art history.

Secondary Sources in Philosophy

Secondary Sources

Secondary sources list, summarize, compare, and evaluate primary information and studies so as to draw conclusions on or present current state of knowledge in a discipline or subject. Often secondary sources not only analyze, interpret, or evaluate primary sources, but also use them to support an argument or to persuade their audience. Secondary sources are written for professional or scholarly audiences, and - sometimes in conjunction with primary sources - are the types of sources most instructors expect you to rely on for your own work, especially scholarly, peer-reviewed secondary sources. Sources may include a bibliography which may direct you back to the primary research reported in the article.

Secondary Sources include:

  • In philosophy, a secondary source is usually a book or academic article written by a scholar on a topic, issue, or philosopher, wherein the scholar will pass judgment on a primary source as well as a body of other secondary sources.

Tertiary Sources in Philosophy and other disciplines

Tertiary Sources

Tertiary sources consist of primary and secondary source information which has been collected and distilled. They present summaries of or an introduction to the current state of research on a topic, summarize or condense information from primary and secondary sources, or provide a list of primary and secondary sources. These include:

  • Encyclopedias (sources like Wikipedia and Credo databases fall into this category)
  • Almanacs
  • Fact books