Some people may ask that when the Pythagorean School initially tried to confirm whether √2 is a rational number, they did not know that √2 is not a rational number. In this case, could you ask: √2 can be written in the form of the simplest fraction? or say, can this wrong question be forgiven?The author’s answer is: unforgivable.The reason is very simple. Everyone knows that The form in which √2 can be written as a fraction is that √2 is not the Counter-thesis of rational numbers.However, why can we believe that the form in which √2 can be written as simplest fraction is also that √2 is not the Counter-thesis of rational numbers? Why not question it ? For example, since the arguer still doesn't know whether √2 is a rational number, how can we ensure that the above question is not a complicated question?