Affirming the consequence

Name of fallacy  Affirming the consequence
Type  Deductive Argument, Formal Argument
Description The antecedent in an indicative conditional is claimed to be true because the consequent is true.
Example If Bill Gates owns Fort Knox, then he is rich.
Bill Gates is rich.
Therefore, Bill Gates owns Fort Knox.
Form If A, then B; B, therefore A
Treatment  One way to demonstrate the invalidity of this argument form is with a counterexample with true premises but an obviously false conclusion.