---
title: One Source Is A Hypothesis
type: anti-pattern
level: L2
status: live
revision: 1
updated: 2026-08-14
systemVersion: 4.2
tags: [verification, sources, reasoning]
rating: 7.25
ratingAxes: useful 8 · evidence 6 · pull 7 · original 7 · form 9
ratingKind: derived
source: triangulation rule, in production
---

# One Source Is A Hypothesis

_Written 2026-08-14 · last verified 2026-08-14 · system v4.2 · live_

**TL;DR** — A claim from one source is a hypothesis. Somewhere between reading and repeating, the qualifier falls off and it becomes a fact that other work is built on. The fix is mechanical: mark single-source claims in the text itself, so the caveat travels with the number instead of staying in the reader's head.

## Pattern

You find a claim that fits. One source, stated confidently, plausible. You use it.

By the next document it has lost its origin and become a premise. Three documents later something is being decided on it.

## Why it looks right

The source was credible and the claim was specific. Demanding a second source for everything is genuinely slow, and most single-source claims are in fact true — which is exactly why the habit survives.

The qualifier also disappears through ordinary compression rather than carelessness. *"One report suggests roughly 40%"* becomes *"about 40%"* becomes *"40%"* across three edits, none of which felt like a distortion.

## Why it fails

The failure is not that single-source claims are usually wrong. It is that **the ones that are wrong are indistinguishable from the ones that are right** once the qualifier is gone, and the confidence attached to a number does not decay with distance from its origin — it grows, because each repetition looks like independent corroboration.

Marketing-sourced statistics compound this. Several outlets citing each other in a circle look like several sources.

## Instead

Mark the status **in the text**, where it survives copying:

> `[single source — unconfirmed]` next to the claim, not in a footnote

Two supporting rules. A strategic claim requires **2 independent** sources before it is stated plainly — and independent means not citing each other, which requires actually checking. And when a claim cannot be confirmed, say that rather than dropping it: *"widely repeated, no primary source found"* is a genuinely useful finding, and it is the sentence that stops the next person from spending an hour on the same search.