If A happens before B, did A cause B?
"The rooster crows, then the sun rises. Therefore, the rooster's crow causes the sunrise!" This sounds silly, but we make this mistake all the time. Just because one thing happens before another doesn't mean it CAUSED it!
Latin: "After this, therefore because of this."
POST HOC FALLACY = assuming that because B followed A, A must have caused B.
Sequence doesn't prove causation! Things can happen in order for many reasons.
Things can be CORRELATED (happen together or in sequence) without being CAUSAL (one causing the other).
Maybe: coincidence, both caused by something else, or one causes the other!
Timing alone doesn't tell us which!
• "I wore my lucky shirt and won the game - the shirt caused the win!"
• "Ice cream sales rise, then drownings rise - ice cream causes drowning!"
• "After vaccination rates increased, autism diagnoses rose - vaccines cause autism!"
All false! (Summer causes both ice cream and swimming!)
To show A causes B, you need:
(1) A happens before B
(2) When A happens, B follows
(3) When A doesn't happen, B doesn't follow
(4) No other explanation fits
Controlled experiments help!
Post hoc fallacy assumes that because B followed A, A caused B - but sequence ≠ causation!
The mistake:
• Observes temporal sequence (A before B)
• Jumps to causal conclusion (A caused B)
• Ignores other possible explanations
• Confuses correlation with causation
Alternative explanations:
1. Coincidence: Random timing overlap
2. Common cause: C causes both A and B
3. Reverse causation: B actually caused A
4. Complex interaction: Multiple factors involved
Real-world impact:
• Superstitions ("I carried rabbit's foot and passed test!")
• False medical claims
• Bad policy decisions based on spurious correlations
Key question: "Could something else explain why these happened in sequence?"
🤔 Which thinking lens(es) did you use?
Select all the lenses you used:
🌱 A Small Everyday Story
"I wore these socks and we won!"
"So the socks caused the win?"
"Well... they're lucky!"
"What if something else caused both?"
"Like... playing well?"
Superstition met reasoning.
See more guidance →
🧠 Thinking habits this builds:
- Distinguishing sequence from causation
- Considering alternative explanations
- Understanding correlation vs causation
- Recognizing superstitious thinking
🌿 Behaviors you may notice (and reinforce):
- Asking "could something else explain this?"
- Questioning coincidences
- Looking for common causes
- Understanding controlled experiments
How to reinforce: "You noticed that just because B came after A doesn't mean A caused B! There might be coincidence, a common cause, or something else entirely."
🔄 When ideas are still forming:
Children might struggle to see alternatives to causal thinking. Use concrete examples.
Helpful response: "Ice cream sales go up in summer, and so do drownings. Does ice cream cause drowning? No - summer causes both! That's a common cause."
🔬 If you want to go deeper:
- How do scientists prove causation?
- What makes superstitions feel true?
- Find a correlation that isn't causation!
Key concepts (for adults): Post hoc ergo propter hoc, correlation vs causation, confounding variables, controlled experiments.