The paradox of tolerance: why Popper's warning still matters in 2025

What if the thing we prize most — openness — is what invites its own undoing?

That’s the unsettling core of Karl Popper’s paradox of tolerance, a concept first introduced in The Open Society and Its Enemies but now echoing through debates about free speech, extremism, and the digital public square. The idea sounds simple: if a tolerant society tolerates everything, including the intolerant, it risks being consumed from within.

Popper’s warning

Popper wasn’t spinning a hypothetical. He had lived through the collapse of liberal democracies at the hands of totalitarians who used the language of freedom to destroy it. His warning was not a contradiction, but a challenge: to draw a line — not between right and left, but between disagreement and destruction. Because unless that line is drawn somewhere, tolerance becomes a suicide pact.

In 2025, the paradox is no longer philosophical speculation. It’s a live dilemma. We see it play out when social media platforms debate whether to deplatform extremist voices or uphold an absolutist view of speech. We see it when protests turn into riots, fueled by misinformation. And we see it in the quiet erosion of civic norms, as hostile ideologies exploit the very freedoms designed to contain them.

Popper’s claim was that unlimited tolerance leads to the extinction of tolerance. But that’s where things get tricky. Who decides what counts as intolerable? How do you prevent justified restrictions from becoming tools of repression?

Critics of Popper’s idea argue that it gives cover to censorship, that it risks turning liberal democracies into gatekeeping machines that stifle dissent. Some claim that a robust society should be able to withstand any idea, no matter how noxious, so long as violence is not incited. Others point to the deeper roots of extremism — economic despair, political alienation — and argue that silencing the intolerant does nothing to address the conditions that produce them.

Drawing the line

Still, the question won’t go away: Can we tolerate everything and still survive as a free society?

This debate cuts across fault lines of politics, religion, and culture. In multicultural democracies, tolerance has to accommodate practices and beliefs that sometimes stand in sharp tension with liberal norms. Where do we draw the line between religious freedom and gender equality? Between cultural tradition and individual rights? It’s easy to chant slogans about inclusivity — much harder to apply them when principles collide.

Popper offered no easy answers. He simply observed that tolerance, to remain viable, must be self-protective. That doesn’t mean silencing those we disagree with. It means recognising when disagreement gives way to destruction — when debate becomes a mask for domination.

The paradox of tolerance doesn’t tell us exactly what to do. But it reminds us what’s at stake if we do nothing.

Because not all intolerance arrives shouting. Sometimes it walks in wearing a suit, quoting scripture, or calling for “justice.” It doesn’t announce itself as a threat. It asks for a platform. Then it takes the mic.

And by the time it starts banning books, arresting dissidents, or erasing inconvenient truths, it’s too late to ask whether tolerance should have had boundaries.

Frequently asked questions

Who was Karl Popper?

Karl Popper (1902–1994) was an Austrian-British philosopher best known for his work on science, democracy, and critical thinking. He championed the idea of the “open society” — a society that embraces free inquiry, debate, and pluralism. His warning about the paradox of tolerance came from witnessing how totalitarian movements used freedom to destroy freedom. Popper also introduced the idea of falsifiability — the principle that scientific claims must be testable and capable of being proven wrong — as the foundation of real knowledge.

What is Karl Popper’s paradox of tolerance?

The paradox of tolerance is a concept introduced by philosopher Karl Popper in The Open Society and Its Enemies. It argues that if a society is tolerant without limit, its ability to be tolerant can eventually be destroyed by the intolerant. In short, unlimited tolerance can lead to the end of tolerance itself.

Why does the paradox of tolerance matter today?

In 2025, the paradox is no longer just theoretical. It plays out in real-time through online extremism, disinformation, and ideological capture of institutions. Popper’s warning reminds us that liberal democracy must defend itself — not by silencing disagreement, but by resisting ideologies that seek to destroy the system from within.

Is Popper’s paradox a justification for censorship?

Not exactly. Popper didn’t advocate for broad suppression of opposing views. He warned against tolerating intolerant ideologies that reject open dialogue and aim to dismantle democratic norms. His challenge was to draw a clear boundary between free expression and threats to a free society.

Who decides what counts as intolerant?

That’s the crux of the debate. Popper offers a principle, not a prescription. The danger lies in handing that power to the wrong people — or applying it unevenly. The challenge is to build institutions and norms that can distinguish between legitimate dissent and destructive extremism without becoming oppressive themselves.

Can liberal societies survive without limits on tolerance?

Possibly — but history doesn’t offer much comfort. Again and again, totalitarian movements have used liberal freedoms to tighten their grip. A society that won’t stand up for its principles — that’s always open, always tolerant — risks collapsing under the weight of its own ideals. Popper saw that danger clearly. Sometimes, survival means drawing a line.