01 – Affirming the Consequent

Affirming the Consequent

Affirming the Consequent is a logical fallacy where a conclusion is drawn from an outcome that could have many explanations, not just the one being offered.

The structure looks like this:

  1. If P, then Q
  2. Q occurred
  3. Therefore, P is true

The problem is simple: Q does not uniquely identify P.

A familiar example

If it’s raining, the ground will be wet.
The ground is wet.
Therefore, it’s raining.

The conclusion feels natural, but it doesn’t follow. Wet ground has multiple possible causes. The observation alone cannot justify the explanation.

Why the reasoning fails

Affirming the Consequent confuses compatibility with confirmation.
Yes, the outcome fits the explanation — but it also fits many others.

Good reasoning requires more than noticing that a result is consistent with a belief. It requires showing that the result would be unlikely without that belief.

Where it commonly appears

This fallacy shows up frequently in arguments involving:

  • Religion
  • Conspiracy theories
  • Pseudoscience
  • Everyday causal claims

Anytime an explanation is accepted because it feels familiar or expected, this fallacy is nearby.

A god-claim example

If a god exists, prayers may be answered.
A prayer was answered.
Therefore, a god exists.

Even if the event occurred, the explanation is not established. Chance, psychology, coincidence, or selective memory remain viable alternatives unless they are ruled out.

The correction

To avoid Affirming the Consequent, ask:

Does this outcome occur only if the explanation is true?

If the answer is no, the argument is incomplete.

The takeaway

Affirming the Consequent mistakes a possible explanation for a proven one.
Seeing an expected outcome does not confirm the cause you prefer.

At OpenLogic, we adjust beliefs to match evidence — not the other way around.

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