Cum hoc ergo propter hoc claims that if two events occur together, one causes the other. It confuses correlation with causation.
Example
“When internet use rises, depression rises. Therefore the internet causes depression.”
(There may be external factors or reverse causality.)
Applied example (political)
“Since there are more inspections, prices rise. Inspections are the cause.”
(Co-occurrence does not prove direct causality.)
Applied example (superstitious)
“Whenever I carry this stone, things go well. The stone protects me.”
(Coincidence is not causation.)
Why it is fallacious
- Co-occurrence does not imply cause.
- There may be a common cause or indirect relations.
- It ignores confounding variables.
How to spot it
- “A happens with B, therefore A causes B”.
- Alternative explanations are omitted.
- Coincidences are presented as proof.
How to respond
- Ask for causal mechanisms and evidence.
- Require controls that rule out hidden variables.
- Consider alternative causal directions.