The Three-Source Rule¶
Why It Matters¶
Single-source stories fail catastrophically. The source may be lying, misremembering, exaggerating, or repeating secondhand information they believe but can't verify. Even well-intentioned sources have incomplete information and cognitive biases. The three-source rule forces you to distinguish between "someone told me this" and "this is sufficiently verified to stake my reputation on." It makes false claims structurally harder to publish because they're harder to corroborate.
The Key Move¶
When you receive a significant claim, ask: "Who else can confirm this independently? What documents would show this? What observable evidence would exist if this is true?" Treat the initial source as a lead, not as evidence. Seek corroboration from sources who weren't in communication with each other and have no shared motivation to lie. If you can't find independent corroboration after genuine effort, either the claim is false, or it's insufficiently verified to publish. Documentary evidence (contracts, emails, financial records, meeting minutes) is stronger than additional human sources because documents can't change their story.
Classic Application¶
Watergate investigation. Bob Woodward had "Deep Throat" (Mark Felt) providing inside information about Nixon administration wrongdoing. Rather than publishing based on this single well-placed source, Woodward and Bernstein corroborated every claim through additional sources (often secretaries, administrative staff, or people tangential to events) and documentary evidence (campaign finance records, phone logs, court documents). Many of Deep Throat's leads couldn't be independently verified and were never published.
Surprising Application¶
Software engineering incident response. When debugging production failures, experienced engineers don't trust single data points. "The logs say X" - but are the logs complete? Clocks synchronized? Does monitoring confirm? Do user reports match? Treating the initial error report as a lead rather than evidence prevents chasing false root causes. One team spent days debugging based on misleading logs before applying three-source verification: logs + database state + network traces revealed the actual issue.
Failure Modes¶
Treating sources as independent when they're actually repeating the same original source (circular reporting - this is why you verify sources didn't communicate). Accepting documentary evidence without verifying authenticity (documents can be forged or altered). Using three sources with shared motivation to deceive (they can coordinate lies). Becoming paralyzed and never publishing because you can't find source three (at some point you publish with caveats about verification limits). Treating the rule mechanically rather than substantively (three sources who all heard the same rumor aren't independent).
Go Deeper¶
Kovach and Rosenstiel, "The Elements of Journalism" Chapter 3 on verification. Weinberg, "The Reporter's Handbook: An Investigator's Guide to Documents and Techniques" (5th ed.) on source corroboration methods. Houston, "Computer-Assisted Reporting: A Practical Guide" on documentary verification.