The Paradox of Tolerance
A reader's summary of the argument that unlimited tolerance undermines itself: where Karl Popper actually put it, what he said around it, how Rawls tightened it, and why it is now quoted in nearly every dispute over who gets to speak online.
The idea at a glance
The paradox of tolerance says that if a society tolerates absolutely everything, including people who would use that freedom to destroy it, the tolerant will eventually be overrun and tolerance will vanish with them. The conclusion people draw from it is that a tolerant society is entitled, within limits, to refuse tolerance to the intolerant. On social media it appears as a one-line reply to anyone who says “let everyone speak,” and as a justification for banning accounts. It is also invoked, from the other side, to accuse moderators of using tolerance as a cover for censorship.
Origin
The Austrian-British philosopher Karl Popper wrote it down in The Open Society and Its Enemies, a two-volume work drafted during the Second World War and published in 1945. It appears in the fourth note to the seventh chapter, in a discussion of Plato and of how democracies can hand power to tyrants. Popper described what he called the less well known paradoxes of tolerance: unlimited tolerance must lead to the disappearance of tolerance, because if we extend it even to those who are intolerant, and are not prepared to defend a tolerant society against them, then the tolerant will be destroyed, and tolerance with them.
History and context
Popper was writing from exile in New Zealand, after Nazi parties had used elections and free speech to reach power in Germany and Austria. The same experience produced the contemporaneous idea of “militant democracy,” a phrase from the German-American jurist Karl Loewenstein in 1937, and later shaped the postwar West German constitution, which allows the banning of parties that attack the free democratic order.
The text is more cautious than its popular form. In the same note Popper says that, as long as intolerant philosophies can be countered by rational argument and held in check by public opinion, suppression would be unwise, and that he does not mean we should always suppress the expression of intolerant philosophies. He reserves the right to suppress them if necessary, even by force, when they forbid their followers to listen to rational argument and teach them to answer arguments with their fists or pistols.
In 1971 John Rawls took the problem up in A Theory of Justice. His answer was that a just society should tolerate the intolerant in general, since otherwise it risks being intolerant itself, and that the exception comes only when the tolerant sincerely and reasonably believe their own security and the institutions of liberty are in danger. The online use of the paradox became common in the 2010s as platforms argued over harassment and extremist content, and again in 2022 when the ownership of Twitter changed hands amid public debate about moderation.
Main ideas
A footnote, not a doctrine
Popper did not write a chapter on it. The argument sits in a note to the seventh chapter of The Open Society and Its Enemies, published in 1945, as a passing observation about how a free society can be undone from inside. Most of the weight it now carries was added by later readers.
Tolerance needs a boundary to survive
The core claim is structural: a society that tolerates everything, including movements that would abolish tolerance if they won, ends up with no tolerance left. The paradox is that preserving the value requires refusing it to someone.
Argument first, force last
Popper said the right to suppress intolerant movements should be claimed only when they refuse rational argument and answer it with fists or pistols. As long as they can be countered by argument and kept in check by public opinion, he called suppression unwise.
Rawls turns it into a test
In A Theory of Justice (1971), John Rawls argued that a just society should in general tolerate the intolerant, and may limit them only when it sincerely and reasonably believes its own security and the institutions of liberty are in danger.
It is a rule for institutions, not for comment threads
The question Popper and Rawls asked was when a state may restrain a movement. The online version asks when a moderator may remove a poster, which is a lower-stakes decision with a lower bar, and one that private platforms make under their own terms of service. It sits close to the problems of the Overton window and shadowbanning.
Critique
- The popular version drops the hedges. Quoted as a slogan, the paradox reads as permission to silence anyone judged intolerant. Popper's own text makes argument the first response and suppression the exception, tied to a refusal to argue and a resort to violence.
- Who decides is the whole question. The paradox says there is a limit and does not say where it is. Whoever holds the power to label a view intolerant can use that label against rivals, so the principle can be turned on the very minorities it was meant to protect.
- Suppression can feed what it targets. Critics argue that banning a movement lends it the glamour of the persecuted and drives it to spaces with no moderation at all. Whether that happens depends on the case, and the evidence on deplatforming is mixed.
- Intolerance is not the same as disagreement. If every strongly held view counts as intolerant, the exception swallows the rule. Popper's test was about incitement and refusing to argue, not about holding an unpopular opinion.
Impact
The paradox gave moderators and legislators a vocabulary for a real trade-off, and it is cited in debates over hate-speech laws, party bans and platform rules. Its practical lesson is narrower than the slogan: a free society may defend itself, but it should say what conduct triggers the defence, apply it evenly, and keep answering with argument for as long as the other side will listen.