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How to Evaluate Historical Sources

Every biography stands or falls on its sources. A diary entry, a newspaper report, a government record and a social-media post are not equal evidence, and a source that is excellent for one question can be useless for another. These six checks will help you weigh any historical source you meet.

Last updated: 13 November 2026

1. Primary or secondary?

Start by asking what kind of source you are looking at. A primary source was created at the time by someone directly involved — a letter, a diary, an official record, a photograph. A secondary source was written later by someone who studied the evidence — a biography, a history book, a scholarly article. Primary sources are closer to the event; secondary sources add context and judgement.

Neither kind is automatically trustworthy. A diary can be self-serving; a history book can repeat an old error. But knowing which kind you hold tells you what questions to ask next.

2. Who wrote it — and why?

Every source has an author with a motive, an audience and a point of view. An autobiography is written to present a life in a good light. A court record is written to settle a dispute. A newspaper report is written to sell copies on the day. None of these motives makes a source useless — but each one shapes what it says and what it leaves out.

Ask three questions: who wrote this, who were they writing for, and what did they want the reader to believe? A source that has no interest in misleading you — a routine administrative record, for example — is usually more credible than one written to persuade.

3. When was it written?

Time matters in two ways. A source written close to the event usually has fresher, more detailed knowledge — but the writer may have been too close to see the whole picture. A source written decades later has perspective and access to more evidence, but memory fades and stories harden into legend.

The strongest position is usually a contemporary record checked against a later scholarly account. If the two agree, your confidence rises; if they disagree, you have found something worth investigating.

4. Does anyone else agree?

A claim that appears in one source and nowhere else is a claim, not a fact. Corroboration — the same message in several independent sources — is the single strongest test of reliability. If three independent sources agree, the credibility of the message is strongly increased; if they all trace back to one original, they are really one source wearing three hats.

This is why this site requires at least three independent sources for every profile. See the sources policy for how independence is judged — a newspaper that quotes a biography is not independent of that biography.

5. What does it not say?

Silence is evidence too. A source that never mentions a major event may be hiding it, may not have known about it, or may have thought it unimportant — and each of those is informative. Ask whose voices are missing: the people a source never quotes are often the people it never asked.

This matters most for figures whose lives were recorded mainly by others. A. P. J. Abdul Kalam wrote extensively about his own life, so his voice is present in his biography; for many historical figures, the record is written entirely by other people, and the gaps are part of the story.

6. Disagreement is information

When good sources disagree, the disagreement itself tells you something. A common confusion is the idea that Muhammad Ali Jinnah was the first President of Pakistan. He was not: he was the first Governor-General, and the first President was Iskander Mirza, from 23 March 1956. The error survives because it sounds plausible and gets repeated — which is exactly why checking matters more than repeating.

Treat every disagreement as a question, not a problem. Work out which source is closer to the event, which has the better evidence, and whether one is copying the other. Then report both sides honestly, as the profiles on this site do.

Frequently asked questions

Is Wikipedia a reliable source?

As a starting point, yes — and as a final authority, no. Wikipedia is useful because its best articles cite their sources, and you can follow those citations to the underlying books, papers and records. But an article with few citations, or one that cites only other web pages, is a lead to check, not a fact to quote. Never rely on a single source, Wikipedia included.

Are older sources better?

Not necessarily. A source written close to the event usually has fresher detail, but the writer may have been biased, mistaken or working with incomplete information. A later historian has distance and more evidence, but may repeat earlier errors. Judge a source by its evidence and its reasoning, not by its age alone.

What should I do if two good sources disagree?

Report both, and weigh them. Ask which source is closer to the event, which has better evidence, and whether one is copying the other. On this site, when two good sources disagree the profile shows both sides rather than quietly picking one — the reader can see the disagreement and judge it.