A tolerant society that tolerates everything will destroy itself

Karl Popper argued that if a society extends unlimited tolerance even to those actively working to destroy tolerance, the intolerant will eventually exploit that openness to seize power and end it for everyone. His conclusion wasn't to suppress all disagreeable ideas, but that a free society must reserve the right to refuse tolerance to movements that reject rational debate itself.

— Karl Popper, The Open Society and Its Enemies — 1945
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