Definition
The Post Hoc Fallacy (short for post hoc ergo propter hoc, Latin for “after this, therefore because of this”) is a logical fallacy that states “Since event Y followed event X, event Y must have been caused by event X.”
Why It Matters
The Post Hoc fallacy is how “Fake News” and “Conspiracies” are born. By weaving a story out of random chronological events, we create “ghost causes” that don’t exist. In business and science, this leads to “False Positives” that waste years of effort. Breaking the “Narrative Instinct” with rigorous testing is the only way to see the world as it actually is, not as we’ve “storied” it.
Core Concepts
- Temporal Sequence vs. Causality: The core error is assuming that a simple chronological relationship implies a causal one.
- Correlation is not Causation: Event X and Y might be correlated without X causing Y (e.g., both might be caused by a third factor Z).
- Spurious Correlations: Random patterns that appear meaningful but have no underlying mechanism.