NF Not a Fact Anymore

Facts have a history.

Knowledge changes.
The record should too.

A catalogue of claims that were once reasonably accepted as factual but were later overturned, replaced, narrowed, reclassified, or corrected by better evidence.

Browse the catalogue Submit a claim

This is not a collection of myths, failed predictions, or things somebody once said. Every entry must show that the previous claim was genuinely supported or treated as authoritative, and that the present understanding is backed by stronger evidence.

Being wrong is not the failure. Refusing to update is.

Featured entry

A clear example of knowledge updating

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Not a fact anymore

Earth’s continents and ocean basins occupy essentially fixed positions.

What we know now

Earth’s rigid outer layer is divided into tectonic plates that move relative to one another. Continents form parts of these plates and are carried along as the plates move.

Why it changed

Ocean-floor mapping, seafloor spreading, symmetrical magnetic patterns in oceanic crust, the ages of seafloor rocks, and the global distribution of earthquakes and volcanoes produced a unified explanation for continental movement during the 1950s and 1960s.

Status
Superseded
Accepted approximately
19th century to the mid-20th century
Changed approximately
1950s–1960s

Not a fact anymore

Peptic ulcers are primarily caused by stress and lifestyle.

What we know now

Most peptic ulcers are caused by Helicobacter pylori infection or by certain medications, particularly nonsteroidal anti-inflammatory drugs (NSAIDs).

Why it changed

Research by Barry Marshall and Robin Warren established the connection between H. pylori, gastritis, and peptic-ulcer disease, replacing the dominant emphasis on stress and lifestyle with an infectious explanation for most cases.

Status
Superseded
Category
Medicine
Accepted approximately
Mid-20th century to the 1980s
Changed approximately
1982–1990s