The paradox of tolerance: why Popper's warning still matters in 2025
Karl Popper’s paradox of tolerance asks whether a free society should tolerate the intolerant. In 2025, amid rising extremism and cultural clashes, his warning feels more urgent than ever.
Karl Popper’s paradox of tolerance has become a recurring theme in today’s debates about free speech, extremism, and the digital public sphere. First introduced in The Open Society and Its Enemies, the idea seems 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.
Nearly a century on, Popper’s warning no longer reads like abstract philosophy. It feels uncomfortably close to real life. You see it in the tension that plays out every day: between free expression and social stability, between open platforms and the risks they carry. Should tech companies remove voices that threaten democratic norms — or does doing so betray those very norms? What begins as debate quickly turns into outrage. Protest blurs into riot. Bad actors learn to hide behind the language of liberty. And the old liberal instincts — to reason, to persuade, to tolerate — start to falter.
Popper’s point was stark: if we tolerate the intolerant without limits, they will dismantle the very system that protects them. But that insight leads straight into a thicket. Who gets to define intolerance? How do we guard against repression disguised as principle?
Some critics argue that invoking the paradox invites censorship. It lets the powerful redraw the bounds of acceptable thought — often in their own image. Others insist that a confident, plural society must withstand even the most unpleasant views, so long as they stop short of inciting violence. Still others look deeper, pointing to the conditions that give extremism its fuel: poverty, mistrust, humiliation. They argue that banning a voice does little to quiet the anger behind it.
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, and 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 lanyard, 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.
Further reading
The Open Society and Its Enemies by Karl Popper.
The foundational work in which Popper introduces the paradox of tolerance, alongside a broader critique of totalitarianism and the threats to open societies.On Tolerance by Frank Furedi.
A deep dive into the evolution of tolerance, examining how its meaning has shifted over time and the challenges of balancing free expression with social harmony.Why Tolerate Religion? by Brian Leiter.
A provocative exploration of whether religious beliefs deserve special legal protection and how this connects to broader debates about tolerance.Can Democracy Survive Global Capitalism? by Robert Kuttner.
While not directly about Popper, this book addresses threats to liberal democracy, touching on themes of tolerance, political extremism, and the fragility of open societies.The Coddling of the American Mind by Greg Lukianoff and Jonathan Haidt.
A discussion of how shifts in discourse, especially around free speech and tolerance, affect democracy, education, and social cohesion.