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Post Hoc Ergo Propter Hoc

F047 • Informal - Causation

Also known as: Post Hoc, False Cause, After Therefore Because

Difficulty 3/10Medium-High LoadExtremely Common

Definition

Assuming that because Event B followed Event A, Event A must have caused Event B.

Why Invalid

Temporal sequence alone doesn't establish causation. Correlation doesn't imply causation. Events may be coincidental or both caused by a third factor.

Edge Cases

  • When controlled experiments establish causation
  • When causal mechanism is known
  • When alternative explanations ruled out
  • When relationship is systematic and strong

Examples

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Scope of Applicability

  1. Identify temporal sequence claim
  2. Check if causal mechanism proposed
  3. Look for alternative explanations
  4. Assess if third variable could explain both
  5. Determine if correlation systematic or coincidental

Common Mistakes

  • Dismissing all temporal sequence arguments
  • Not considering that some temporal sequences do indicate causation
  • Ignoring strength and consistency of correlation

Related Concepts

Cum Hoc Ergo Propter HocShifting Burden of ProofArgument from Incredulity

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F048 Cum Hoc Ergo Propter Hoc
Return to 4.1 Before and Because