Primary or secondary sources: which are more reliable?

A history professor thinking while looking out of a library window
© History Skills

When conducting historical research, both primary and secondary sources provide information that help us to answer the questions we’re trying to answer.


However, when using evidence from these kinds of sources, which one do we trust more? 


Are primary sources inherently more trustworthy than secondary sources, or vice versa?  


In this blog post, we will explore the differences between these two types of sources, the advantages, and disadvantages of each, and how to effectively utilize them in your research. 

What are primary and secondary sources?

Primary sources are documents or artifacts that were made at the time of the events they describe.


This means that they are often firsthand accounts by people who experienced the events personally.


Common examples of primary sources include diaries, letters, photographs, interviews, newspaper articles, legal documents, and artifacts. 


On the other hand, secondary sources are documents that are created after the events they describe, and the author was not personally involved.


They rely upon the information provided by primary sources to build a more comprehensive understanding of the event.


Examples of secondary sources include textbooks, biographies, journal articles, and documentaries. 


In determining which of these two kinds of sources is best, it is important to note that both primary and secondary sources have some clear benefits over each other.

Advantages of primary sources:


Primary sources offer an unfiltered view of the past, providing firsthand accounts of events, thoughts, and feelings. 


Unique perspectives:

Since primary sources are created by individuals, they often reveal diverse and unique opinions on the events they describe. 


Often hard to find:

For many events in history, we only have one written version about it and, if it were lost, we would lose everything we know about it. 

Advantages of secondary sources:

Provide context:

Secondary sources provide a broader context and interpretation of primary sources, making it easier to understand their significance. 


Broad synthesis:

These sources often incorporate multiple primary sources, offering a more comprehensive understanding of the subject matter. 


Easier to read:

Secondary sources are usually more accessible and easier to understand, as they are written in a more organized and coherent manner. 


Written by experts:

Many of the best secondary sources are written by experts in their fields, such as professional historians, researchers, or academics.

So, the most reliable kind of source is...



Just because a source a primary or secondary source does not make either more reliable than the other.


Instead, each individual historical source needs to be evaluated on its own merits in order to determine how much you can trust the information it provides.  


Being able to identify whether a source is primary or secondary is only the first step in analysing it in order to form a judgment about its trustworthiness. 


In fact, both primary and secondary sources have their advantages and limitations. 

But aren’t primary sources more reliable because they are from eyewitnesses?

Primary sources are not automatically reliable just because they are from eyewitnesses.


While primary sources do provide valuable direct evidence and firsthand accounts, they can still be subject to inaccuracies, biases, or distortions.  


Here are some reasons why primary sources may not be completely reliable: 


Subjectivity and bias:

Eyewitness accounts are often influenced by the personal opinions, beliefs, and emotions of the individuals who create them. These biases can impact the way events are perceived and recorded, leading to potential inaccuracies or distortions. 


Memory limitations:

Human memory is imperfect, and over time, recollections of events can become distorted or inaccurate. Eyewitnesses may forget certain details or even remember events in a way that did not actually occur, which can affect the reliability of their accounts. 



Eyewitnesses may misinterpret or misunderstand the events they are witnessing, leading to inaccuracies in their accounts. They may not have a complete understanding of the context or significance of what they are observing, which can impact the reliability of their reports. 


Selective reporting:

Eyewitnesses may selectively report certain details of an event based on what they deem important, interesting, or relevant. This can result in an incomplete or skewed representation of the event. 

But aren't secondary sources automatically more reliable when experts write them?

Secondary sources are not automatically more reliable simply because they are written by academics.


While academics often have expertise in their fields and are trained in research methodologies, secondary sources can still be subject to inaccuracies, biases, or distortions.


Here are some reasons why secondary sources may not be completely reliable: 


Reliability of primary sources:

Secondary sources are based on primary sources, and if the primary sources used are inaccurate or biased, the secondary sources may also be affected by these issues. The reliability of a secondary source is dependent on the quality and accuracy of the primary sources it draws from. 


Biased interpretations:

Secondary sources involve interpretation and analysis of primary sources by the author. These interpretations can be influenced by the author's own biases, perspective, or theoretical frameworks, which may lead to a skewed or partial understanding of the subject matter. 


Overgeneralization or oversimplification:

In an effort to provide a comprehensive view, secondary sources may sometimes overgeneralize or oversimplify complex issues, potentially leading to a loss of nuance or important details. 


Miscommunication or misunderstanding:

Errors can occur in the process of interpreting, summarizing, or analyzing primary sources. The author of a secondary source may misinterpret or misunderstand the primary sources they are working with, leading to inaccuracies in their analysis. 

The need to critically assess all sources

Analyzing and evaluating both primary and secondary sources is crucial for obtaining a comprehensive, accurate, and nuanced understanding of a subject.


Each type of source offers unique advantages and has its own limitations, making it essential to use them in conjunction to achieve a well-rounded perspective.  


When selecting your sources during your historical research, here are some good guidance principles to ensure you use your sources well, regardless of whether they’re primary or secondary: 


Corroborate the information: 

Cross-referencing primary and secondary sources helps to verify the accuracy of the information presented in each source. It allows researchers to identify potential inaccuracies, biases, or distortions, ensuring that the final conclusions drawn are based on reliable information. 


Look for different perspectives: 

Primary and secondary sources often reflect diverse perspectives and viewpoints, allowing researchers to consider multiple angles and interpretations when studying a subject. This can help to mitigate the impact of biases, reveal hidden patterns or connections, and generate a more nuanced understanding of the topic. 


Contextualize your sources: 

Evaluating primary sources considering secondary sources can help place them in their proper historical, cultural, or social context. This contextualization is vital for understanding the significance of primary sources and accurately interpreting the information they contain. 

Critical thinking is the best skill to learn

As should be clear by now, neither primary nor secondary sources are inherently better than the other.


Both types of sources play critical roles in research and should be used in conjunction with one another to obtain the most accurate and comprehensive understanding of a subject.  


Therefore, the reliability of a source should be assessed on a case-by-case basis, considering the factors mentioned above.


By understanding the strengths and limitations of each type of source, you can optimize your research process and produce a far more sophisticated assessment piece. 

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