Paradox of Tolerance

Wikipedia:

The paradox of tolerance states that if a society is tolerant without limit, its ability to be tolerant is eventually seized or destroyed by the intolerant. Karl Popper described it as the seemingly paradoxical idea that, “In order to maintain a tolerant society, the society must be intolerant of intolerance.” Popper expands upon this, writing, “I do not imply for instance, that we should always suppress the utterance of intolerant philosophies; as long as we can counter them by rational argument and keep them in check by public opinion, suppression would be most unwise. But we should claim the right to suppress them if necessary even by force…”