It is commonly accepted in our time that to have a just society that accepts diversity as well as freedom of speech and opinion that come with this diversity, we must practice tolerance. And tolerance is understood as allowing or accepting the actions, ideas or the people that we disagree with. But immediately, a very complex and difficult problem appears to us. If we are to accept all diversity in opinion that we don't agree with, what about the people that don't want to accept others they disagree with? Should we tolerate them?
This is precisely the question that 20th century philosopher Karl Popper raised. In Chapter 7 of his book, the Open Society and Its Enemies, he poses the very famous "paradox of intolerance". In his own words, he suggests that "in order to maintain a tolerant society, the society must be intolerant of intolerance." And the fact that something that calls for tolerance so much has to practice essentially the opposite of tolerance is something that is considered paradoxical-as in, it appears contradictory but he considers it true.
Karl Popper defends his position by saying that if we allow unlimited tolerance, intolerance will use its freedom to attack tolerance and destroy it. And that is not what we want. This is why he says we should not tolerate tolerance. He does not however want us to silence or censor them, but to fight them back with reasonable arguments. He does however say we should have the right to be intolerant (even violently!) to them if they are not ready for a debate, as they may prevent "their followers [from listening] rational argument, because [they say] it is deceptive, and teach them to answer arguments by the use of their fists or pistols."
However, if that appears too violent or forceful, we may instead go with what fellow 20th century philosopher, John Rawls, told us instead. It may be somewhat different but perhaps more balanced.
In page 220 of his book, A Theory of Justice, John Rawls says that we should tolerate intolerance, or else the society will itself become intolerant. However, he comes to a similar conclusion as Popper: in extreme consequences, a tolerant society still has the right to self defense, but he adds a condition to what Popper said--only when the tolerant "sincerely and with reason" believe that their own safety and liberty are in danger.
In essence, John Rawls tells us that we should allow intolerance as a right and freedom, just as long as it doesn't go against the right and freedom of the other.
Today, as diversity in opinion is everywhere and the idea of tolerance is more powerful than ever, it is time to reflect upon these positions. And it is even more important to discuss the limits of free speech and at the same time, the limits of censorship. It is bad to be intolerant, but it is bad to hold back freedom of speech. So, where is the middle ground? Where does your right to be intolerant end, and where does my right to fight back end?