Denying the antecedent

Denying the antecedent is when you conclude that an effect did not happen because its usual cause did not happen—even though the effect can have other causes. In other words: "If A then B; A is false; therefore B is false" is invalid. We often think that stopping the cause stops the effect, but the effect might still occur for a different reason. The argument form is broken because it ignores other possible causes.

Examples

• If I eat peanuts I get hives. I didn't eat peanuts. So I won't get hives.

• If you train hard, you'll get fit. You didn't train hard. So you won't get fit.

• If the company had cut costs, profits would have fallen. The company didn't cut costs. So profits didn't fall.

• If the vaccine is taken, infection rates drop. They didn't take the vaccine. So infection rates didn't drop.