Fundamentals

The Paradox of Tolerance: What Popper Meant

By Daniel Sardá · Published on September 24, 2026

6 min read1,223 words

Unlimited tolerance can destroy the conditions that make tolerance possible. Popper's warning, however, is not a general license to censor.

The paradox of tolerance begins with an apparent contradiction: a tolerant society may need to set limits on certain forms of intolerance in order to remain tolerant. If it allows people to intimidate, persecute, or eliminate those who think differently without resistance, it may ultimately lose the pluralism it meant to protect.

The idea is often reduced to “do not tolerate the intolerant.” The phrase is appealing, but it is also dangerous. Read without context, it can turn a warning about defending the open society into permission to silence anyone labelled “intolerant.”

Karl Popper raised a more precise problem. His argument does not end debate or turn every offensive opinion into violence. It asks what a society should do when some people use its freedoms to destroy the freedoms of others.

Key idea: The paradox does not say that every intolerant idea should be banned. It warns that tolerance cannot require passivity in the face of persecution, coercion, or violence.

Where the paradox of tolerance comes from

Popper formulated the paradox in a note to chapter 7 of the first volume of The Open Society and Its Enemies, first published in 1945. It was not a detailed legal rule, nor the central argument of the entire book, but a reflection on the conditions that make it possible to preserve an open society.

His reasoning begins with a troubling possibility. If a society extends unlimited tolerance even to movements willing to suppress rational exchange and persecute their opponents, those movements could destroy both their opponents and the tolerant order itself.

But the context matters. Popper does not propose immediately suppressing the expression of every intolerant philosophy. As long as it is possible to answer it with rational argument and public opinion can contain it, he considers prohibition unwise. The question changes when a movement rejects debate as a method, teaches people to answer with violence, or seeks to prevent others from speaking and exercising their rights by force.

The paradox therefore describes a tension, not a shortcut. An open society must preserve room for mistaken, unpleasant, and even hostile ideas. At the same time, it is not obliged to stand defenselessly by while the rules that make that room possible are destroyed.

Tolerating is not approving

Tolerance makes sense only when there is an objection. We tolerate a belief or practice that we consider mistaken, inconvenient, or morally objectionable because there is a higher reason not to prevent it: respect for another person's freedom, civil peace, or equal rights. When we agree, tolerance is unnecessary; we simply approve.

This distinction prevents two common confusions. The first is to think that allowing an opinion amounts to endorsing it. The second is to assume that criticizing an idea is itself intolerance. In a plural society, people can defend, refute, ridicule, abandon, or reject ideas without asking the authorities to ban them.

Tolerance and rights are related, but they are not identical. A citizen keeps their freedoms not because others deem their convictions valuable, but because the rules protect everyone equally. That protection includes political rights and the right of others to disagree and respond.

Essential distinction: Tolerating an opinion means allowing it to be expressed; it does not mean declaring it true, respectable, or immune from criticism.

An opinion is not the same as a threat

To apply the paradox prudently, it helps to distinguish among different levels: ideas, expression, organization, and conduct. Blurring them allows a vague word—“intolerance”—to decide by itself what may be said or done.

Imagine a person who holds an offensive and exclusionary doctrine. Others may challenge it, withhold their support, organize a peaceful protest, or try to persuade its audience. Those responses are also part of freedom of expression. Intense disagreement does not necessarily destroy an open society; it often shows that the society remains open.

Now imagine a group that threatens people attending a meeting, forcibly blocks their access, or persecutes a minority to prevent it from exercising rights shared by all. This is no longer an idea competing in debate. Intimidation or coercion has entered the picture, changing the conditions of exchange and reducing others to silence.

The boundary will not always be simple, but that does not justify erasing it. Speech can be cruel without constituting a threat; an organization can advocate radical change without using violence. Likewise, coercion does not cease to be coercion merely because it is presented as political opinion.

How an open society can respond

The paradox does not force a choice between indifference and censorship. There is a range of responses, and not all belong to the state. Criticism, education, journalism, voluntary association, and the withdrawal of support are social tools. A legal prohibition, by contrast, activates coercive power and therefore requires stricter justification.

A response compatible with an open society should attend to at least four criteria:

• Identifiable conduct: assess threats, persecution, coercion, or attacks on rights—not a vague ideological label.
• [General rules](/en/fundamentals/general-laws): apply the same principles to allies and opponents, without turning power into an arbiter of acceptable opinions.
• Proportionality: prefer discussion and less restrictive responses when they can still be effective.
• Institutional safeguards: require public procedures, review, and limits on power to reduce arbitrary decisions.

These criteria do not settle every concrete case. They do help prevent two opposite mistakes: responding too late to a real threat, or using a hypothetical threat as an excuse to punish dissent.

Practical criterion: Institutional defense should address acts that deny equal rights or replace persuasion with force, not the mere existence of unpopular opinions.

This criterion does not eliminate difficult disagreements, but it guides the limits of coercion: protecting public discussion requires preventing force from silencing those who take part in it.

The risk that power will abuse the paradox

The strongest objection to an expansive reading is clear: those in government could call any opponent “intolerant.” If an accusation alone is enough to exclude someone from debate, the supposed defense of tolerance reproduces the very authoritarianism it claims to oppose.

This is why the rule of law matters. Limits must rest on known rules, equal rights, and procedures that also protect the accused. A stated intention to defend democracy does not make every measure just.

This point is especially important from a liberal perspective. Freedom does not depend on a ruler correctly identifying the good and the bad, but on institutions that restrict the ruler's capacity to impose that classification. Protecting an open society requires attention to both private threats and abuses of public power.

A warning, not a license to censor

The paradox of tolerance retains its value when read with limits. It reminds us that pluralism needs protection: no one has a right to drive others out of common life through persecution, intimidation, or violence. It also reminds us that such protection can become corrupt when it relies on vague categories and discretionary decisions.

The decisive question is not who seems unpleasant or which idea provokes the greatest rejection. It is whether an exchange still exists in which everyone retains equal rights, or whether someone is trying to replace persuasion with force. While debate remains possible, an open society relies first on reason, criticism, and public opinion. When coercion appears, it can defend its rules without abandoning the principles it seeks to preserve.