What does post hoc ergo propter hoc mean?

It is Latin for “after this, therefore because of this”. It names the error of treating the order of events as evidence of cause: B happened after A, so A must have produced B.

What is an example of the post hoc fallacy?

A town installs brighter streetlights in January, reports fewer burglaries by March, and credits the lights. Unless someone checks whether burglaries usually drop over those months, or dropped in neighbouring towns too, the timing proves nothing.

How is post hoc different from “correlation is not causation”?

They are close relatives. Post hoc is about sequence, where one event came first. The correlation warning covers any two things that move together, whichever comes first. Both mistake an association for a cause.

Is it always wrong to infer cause from timing?

No. A cause has to come before its effect, so timing is a legitimate starting clue. The fallacy lies in stopping there. Ruling out alternatives, repeating the observation and using comparison groups is what turns a hunch into a reasonable causal claim.

Post hoc fallacy (post hoc ergo propter hoc)

Also called post hoc ergo propter hoc, post hoc reasoning · Logical fallacy · Causal reasoning

The post hoc fallacy is assuming that because one event followed another, the first must have caused the second. The Latin phrase means “after this, therefore because of this”, and timing on its own never establishes a cause.

By the ReadGlobe Editors · Reviewed 2026-10-24

Why does the post hoc fallacy (post hoc ergo propter hoc) persuade?

People are pattern-seekers, and spotting causes is so useful that the mind proposes them eagerly, often on the strength of a single instance. When something happens straight after an action, the connection feels self-evident, particularly if that outcome was hoped for. Coincidence, a hidden third factor, or a problem that would have cleared up regardless all go unexamined. Plenty of conditions improve without help, so whatever was tried last tends to collect the credit. Sequence remains a useful clue; the mistake is treating it as the entire proof.

Examples of the post hoc fallacy (post hoc ergo propter hoc)

A cold clears up two days after starting a herbal remedy, and the remedy gets the credit, though most colds pass on their own.
A new manager arrives in spring and sales climb; nobody checks whether sales climb every spring.
A footballer wears the same socks after a win and is convinced they helped.
A supplement advert features customers who “felt more energetic” after a month, with no comparison group in sight.

How do you spot it and respond?

Ask what else changed around the same time, and whether that could account for the result.
Consider what would have happened without the supposed cause. Would the cold, the sales figures or the mood have recovered anyway?
Look for repeated, controlled comparisons before accepting a causal claim, rather than relying on one well-timed coincidence.

Frequently asked

What does post hoc ergo propter hoc mean?: It is Latin for “after this, therefore because of this”. It names the error of treating the order of events as evidence of cause: B happened after A, so A must have produced B.
What is an example of the post hoc fallacy?: A town installs brighter streetlights in January, reports fewer burglaries by March, and credits the lights. Unless someone checks whether burglaries usually drop over those months, or dropped in neighbouring towns too, the timing proves nothing.
How is post hoc different from “correlation is not causation”?: They are close relatives. Post hoc is about sequence, where one event came first. The correlation warning covers any two things that move together, whichever comes first. Both mistake an association for a cause.
Is it always wrong to infer cause from timing?: No. A cause has to come before its effect, so timing is a legitimate starting clue. The fallacy lies in stopping there. Ruling out alternatives, repeating the observation and using comparison groups is what turns a hunch into a reasonable causal claim.

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ReadGlobe. (2026). Post hoc fallacy (post hoc ergo propter hoc). https://readglobe.com/fallacy/post-hoc/

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"Post hoc fallacy (post hoc ergo propter hoc)." ReadGlobe, 24 Oct. 2026, readglobe.com/fallacy/post-hoc/.

Editorial synthesis © ReadGlobe 2026, drawing on the Internet Encyclopedia of Philosophy and the Stanford Encyclopedia of Philosophy entries on fallacies and the logic and critical-thinking literature they cite. · Last reviewed 2026-10-24.