Sequence Is Not a Causal Link
When one event follows another, the timing can make the first event feel like an explanation. The rooster crows; daylight arrives. But the order alone does not show that the crowing produced the sunrise. Both events have their own causes, and the apparent connection may be coincidence or a shared influence.
This mistake is called the post hoc fallacy, from a Latin phrase meaning “after this.” It turns “B happened after A” into “A caused B” without checking what would have happened if A had not occurred.
Why the Mistake Matters in Economics
The same leap can distort judgments about a business decision or public policy. Suppose sales rise after a company changes its prices. The change may have helped—but seasonal demand, a competitor’s actions, or another simultaneous change could also explain the increase. A before-and-after comparison shows timing, not which factor made the difference.
To test a causal claim, analysts look for a credible comparison: what happened to a similar group, market, or period that did not receive the change? They also consider other explanations and whether the proposed cause could plausibly produce the outcome. These checks cannot always settle the question, but they make it harder to mistake a coincidental sequence for evidence.
The practical lesson is simple: ask what would have happened without the first event. If the outcome would likely have occurred anyway, being first in the sequence is not enough to claim credit—or assign blame.
