The concept of relative prime and its truth or falseness are both applied on two integers. Now that Pythagorean School and the later generations already knew the statement that both p and q are integers is false, they should know the last question is a complex problem.Complex question does not have a true or false answer. For example, the question in the ancient Greece; neither the hypothesis that “you have stopped hitting your father” nor the hypothesis that “you haven’t stopped hitting your father” has any meaning or truth or falseness. Since the given counterproposition, √2=p/q (p and q are relative primes), is the answer to the complex question that “are p and q in √2=p/q relative primes”, the counterproposition has no meaning of truth or falseness. So, why can the reductio ad absurdum be applied here?