Logic 101 (#48): Affirming the Consequent

gametheory101.com/courses/logic-101/

In logic, affirming the consequent is a formal fallacy in which an individual claims that knowing P implies Q and that Q is true allows him to conclude that P is true. Unfortunately, there is insufficient evidence to claim this: P may or may not be true.

For example, if you know

“If I win the lottery, I am rich.”

and

“I am rich.”

are true, you cannot conclude that I won the lottery. (I may be rich for reasons unrelated to the lottery—i.e., that sweet, sweet YouTube ad revenue.