Lesson 266 of 1570
The Three-Source Rule
Smart researchers don't trust any single source. They cross-check claims across at least three independent sources before treating something as fact.
Lesson map
What this lesson covers
Learning path
The main moves in order
- 1Why one source is never enough
- 2cross-reference
- 3independent sources
- 4corroboration
Concept cluster
Terms to connect while reading
Section 1
Why one source is never enough
If only one source claims something, you don't know if it's a careful finding or a mistake. If three independent sources arrive at the same conclusion separately, you have real confidence.
This is called triangulation. Real journalists, scientists, and historians all use this approach.
A simple workflow
- 1Find your first source — note the specific claim
- 2Search for the same claim from a different organization
- 3Find a third — ideally from a different country or era
- 4If all three agree, you can trust the claim
- 5If they disagree, dig deeper into why
AI and the three-source rule
Asking three different AI models the same question doesn't count as three sources — they may all be trained on similar data and inherit the same errors. AI is one source. Always pair it with two human-written sources.
Key terms in this lesson
The big idea: real research isn't about finding one source — it's about finding three that all point to the same truth, independently.
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