Wiki - The paradox of tolerance states that if a society is tolerant without limit, its ability to be tolerant is eventually ceased or destroyed by the intolerant. Karl Popper described it as the seemingly self-contradictory idea that in order to maintain a tolerant society, the society must retain the right to be intolerant of intolerance.
I am not looking for dictionary definition. What I am asking is who or what defines what is considered intolerant? Many ideas were considered intolerant before but become accepted and vice versa.