Denying the antecedent

Denying the antecedent means taking a statement like "if A then B" and saying that because A is not true, B cannot be true either. To help explain this, imagine a classroom where all students must wear blue uniforms. In this case, the statement "If a student is wearing a blue uniform then they are in the classroom" is true. But if the student is not wearing a blue uniform, then denying the antecedent states that they cannot be in the classroom either.