The fallacy of affirming the consequent (abbreviated FAC) occurs when the consequent of a conditional (the "then" part of an if-then statement) is affirmed, and then a conclusion is drawn, invalidly, that asserts the antecedent of that conditional (the "if" part of the if-then statement).

For example:

1. If it rains, then the sidewalk gets wet.

2. The sidewalk is indeed wet.

3. Therefore, it is raining.

In general, the form of this fallacy is:

1. If P then Q.

2. Q.

3. Therefore, P.

The example above illustrates this form where:

P = it's raining

Q = the sidewalk is wet