The Paradox of Tolerance: Popper and the Limits of Accepting Everything

There's a phrase that circulates a lot these days — in social media, in political debates, in dinner table conversations. It goes something like this: "We should be tolerant of everyone." And that sounds good, right? It sounds like something a decent person would say. It sounds progressive, open-minded, civilized. The problem is that this phrase, taken to its logical conclusion, destroys exactly what it's trying to protect. And there's a man who demonstrated this with almost surgical precision. His name is Karl Popper. And what he wrote in 1945 — with the smoke of the Holocaust still in the air — remains one of the most uncomfortable and necessary ideas in all of modern political philosophy.

Here we'll walk through the paradox of tolerance. We'll talk about why tolerating everything can be the shortest road to the end of tolerance. And we'll also talk about the criticisms this idea has received — because not everyone agrees with Popper, and the objections raised against him are as interesting as the original idea.

Karl Popper was born in Vienna in 1902, in a Jewish family that had converted to Protestantism when he was very young. Vienna in the early twentieth century was an extraordinary city. It was the capital of a decaying empire — the Austro-Hungarian Empire — but also an unparalleled intellectual hotbed. Freud was inventing psychoanalysis there. The Vienna Circle was debating philosophy of science with an almost religious seriousness. Musicians like Schoenberg were breaking all the rules of harmony. It was a city where you could run into Wittgenstein in a café and end up arguing about language until three in the morning.

Popper grew up in that environment. He was a curious, restless kid who started out studying music, then got into philosophy, mathematics, and physics. As a young man he went through a Communist phase, which wasn't unusual in that era for a young intellectual with social conscience. But he became disillusioned pretty quickly when he saw that Marxism, in practice, could justify anything — violence, the sacrifice of real people in the name of a future utopia that nobody could guarantee would arrive. That marked him deeply.

And then Hitler came.

When the Nazis took power in Germany in 1933, the situation in Austria grew increasingly tense. In 1938, Hitler annexed Austria to the Third Reich in what became known as the Anschluss — the "union," though nobody asked the Austrians who didn't want to be "united." For Popper, with his Jewish background, staying was a death sentence. He had the luck and foresight to have landed an academic position in New Zealand years earlier. He left just in time. His mother died during the war. Part of his family was murdered in the extermination camps.

Popper wrote his most important work — The Open Society and Its Enemies — while in New Zealand, isolated from the world, without great libraries at hand, working as a professor at a small university. He wrote it between 1940 and 1943, in the middle of the war, with tremendous urgency, like someone who feels they're drafting something necessary — something the world needs to read so it doesn't make the same mistakes again. And in that book, almost in passing, in a footnote, he dropped the idea that brings us here today.

The paradox of tolerance.

Before getting into the paradox itself, we need to understand what tolerance actually means as a philosophical concept — because it's not as simple as it appears.

When we say someone is tolerant, in the philosophical and political sense, we're not saying they like everything. Tolerance implies exactly the opposite: I tolerate something I don't like, something I disagree with, but that I allow to exist because I recognize that diversity of ideas and practices is a good in itself. I tolerate someone who thinks differently not because I think it's all the same whether they think differently, but because I understand that society is better when there is freedom of thought and expression.

That idea has a long history. It begins with the religious conflicts of the sixteenth and seventeenth centuries in Europe. When Protestants and Catholics were killing each other in wars that lasted decades, some thinkers began to suggest that maybe the state should stay out of religious affairs. John Locke, in his Letter Concerning Toleration in 1689, was one of the first to argue systematically that people should be able to believe what they want as long as they don't harm others. Over time that idea expanded. It was no longer just religious tolerance but tolerance of ideas in general, of lifestyles, of cultural differences. And it became one of the core values of modern liberal democracies. Tolerance as a founding value. Tolerance as something sacred.

And that's exactly where Popper raised his hand and said: hold on — there's a problem here.

The paradox of tolerance can be stated very simply. If a society is completely tolerant, with no limits, what happens when a group appears that uses that tolerance to promote intolerance? What happens when people exploit freedom of expression to advocate for destroying freedom of expression? What happens when a movement uses democratic rules to gain power and then eliminates those very rules?

The logical answer, says Popper, is that the society won't survive. If you're tolerant of the intolerant, the intolerant will use that tolerance to seize power and destroy tolerance. The end result is a completely intolerant society. Unlimited tolerance destroys itself.

And here comes the conclusion that makes a lot of people uncomfortable: if you want to preserve tolerance as a value, you have to be intolerant of intolerance. You have to draw a line. You have to say: this is where tolerance ends, because beyond this point there are ideas that threaten the very existence of a tolerant society.

That sounds contradictory. It sounds like you're saying "to defend freedom, you have to limit freedom." But Popper argues it's not contradictory at all. It's simply the rational application of a value: if you want tolerance to survive, you have to protect it from its enemies.

It's worth reading exactly what Popper wrote, because the precision of his argument matters. In that footnote in The Open Society and Its Enemies, he says: "Unlimited tolerance must lead to the disappearance of tolerance. If we extend unlimited tolerance even to those who are intolerant, if we are not prepared to defend a tolerant society against the onslaught of the intolerant, then the tolerant will be destroyed, and tolerance with them."

And then he adds something crucial: "I do not imply, for instance, that we should always suppress the utterance of intolerant philosophies; as long as we can counter them by rational argument and keep them in check in this way, their suppression would certainly be imprudent."

The Weimar Republic — the German democracy that existed between 1919 and 1933 — is the case Popper had in mind. It was a young democracy, with enormous economic problems and a society traumatized by World War I. In that context, the Nazi Party used every available democratic mechanism to come to power. They participated in elections. They used freedom of the press to spread their ideas. They used freedom of association to organize their forces. And when they came to power, the first thing they did was dismantle democracy.

The Weimar Republic was not prepared to defend its own institutions from those who wanted to destroy them from the inside. The mechanisms for protection existed, but nobody wanted to use them in time because it seemed anti-democratic to restrict a party that was winning elections.

Popper saw all that. And he said: a democracy cannot commit suicide out of an excess of scruples.

Now, the paradox of tolerance is a powerful idea. But it's not an idea without cracks. Since Popper formulated it, several philosophers and political theorists have pointed out serious problems with it. And it's worth taking the time to examine them, because the criticisms are as revealing as the original idea.

The first criticism is perhaps the most direct: intolerance doesn't always destroy tolerance. Popper's argument assumes that if a society tolerates intolerant ideas, those ideas will necessarily win and end up destroying tolerance. But history doesn't always confirm that. There are societies that have coexisted for decades with extremist and radical movements without those movements ever managing to dismantle their institutions. The Netherlands tolerated the Communist Party for a long time, even though it was explicitly anti-democratic in its platform. The system survived. The United States tolerated the Ku Klux Klan for generations without that meaning the end of American democracy — though at enormous cost to the communities affected. The question that arises then is: when exactly does tolerating intolerance become dangerous? Is there a clear line, or are we talking about something that depends enormously on historical context, institutional strength, and the political culture of each society?

Popper didn't have a fully satisfying answer to that. The mechanism he describes — where tolerance of intolerance inevitably destroys tolerance — is more a warning than a demonstrable social law.

The second criticism is more philosophical and has to do with a distinction Popper tends to blur: the difference between speech and action. Saying something intolerant is not the same as doing something intolerant. Spreading ideas that deny rights to certain groups is one thing. Organizing militias to attack them is something else entirely. Most democratic legal systems make exactly that distinction: freedom of expression protects ideas, even repugnant ones, but doesn't protect acts that directly harm other people.

When Popper talks about being intolerant of intolerance, is he talking about suppressing ideas or suppressing actions? If he's talking about suppressing violent or illegal acts, there's no paradox: all democracies already do that. The paradox only appears when we're talking about suppressing ideas, censoring speech, banning political parties or publications. And there the situation gets complicated, because history shows that the suppression of ideas rarely produces the results its defenders hope for. Sometimes the suppression of a movement turns it into a martyr, gives it a persecution narrative that boosts its growth.

The third criticism is the most practical and perhaps the most urgent: the problem of who decides. Let's accept for a moment that Popper's paradox is correct and that certain forms of intolerance need to be limited. The immediate question is who has the authority to draw that line. The government? The courts? An independent regulatory agency? Private technology platforms?

Each of those options has serious problems. If it's the government that decides what counts as intolerant, there's an enormous risk that this power will be used to silence legitimate political opposition. You don't have to go very far in history to find examples of governments using exactly that argument to persecute their critics: "We're banning this party because it's anti-democratic, because it threatens the values of the open society." The argument can be perfectly sincere. Or it can be a pretext. And from the outside it's not always easy to tell them apart.

If it's the judiciary that decides, there are greater guarantees of independence, but judges also have their biases and limitations. And if it's private technology platforms — as increasingly happens in practice — then the fate of public debate ends up in the hands of corporations that answer to their shareholders, not to the citizenry.

Popper acknowledged this problem but never fully resolved it. He trusted that democratic institutions, with their checks and balances, could make those decisions with sufficient wisdom. But that trust assumes the institutions are strong enough and honest enough not to abuse the power we're granting them. And that's not always a safe assumption.

The fourth criticism is probably the most uncomfortable of all, because it cuts to the heart of the argument: the risk of becoming authoritarian to avoid authoritarianism. If defending democracy requires suppressing parties, censoring publications, imprisoning political leaders, banning rallies — how much democracy is left standing after all that? There's a real danger that the cure is worse than the disease. That by fighting intolerance with restrictions on civil liberties, you end up building exactly the kind of society you said you wanted to avoid. A state that decides which ideas are dangerous and which are not is a state that has already crossed an important line. And once that line is crossed, it's very hard to go back.

There's a name for this in political science: the trap of authoritarian antifascism. Regimes that started with the noble intention of fighting totalitarianism and ended up adopting its methods. Twentieth-century history is full of those cases.

So who is right? Popper or his critics?

The honest answer is that both are partially right, and the tension between their positions doesn't resolve with a clean formula.

Popper is right about something fundamental: tolerance is not a value that sustains itself on its own. A society that actively tolerates its own destruction will not survive indefinitely. Democracy requires certain minimum conditions to function, and there are forces that seek to eliminate exactly those conditions. Ignoring that in the name of an abstract tolerance is naive and potentially suicidal.

But his critics are also right about something equally fundamental: the remedy can be as dangerous as the disease. The mechanisms for suppressing intolerance can easily become mechanisms for suppressing legitimate dissent. The distinction between speech and action matters. And the question of who decides is just as urgent as the question of what gets decided.

What's left of all this is not a clear answer but a framework for thinking. A set of questions that every democratic society should ask itself honestly and regularly. When does an idea stop being a legitimate opinion and become an operational threat to institutions? Are we using the normal mechanisms of public debate before resorting to suppression? Who is making these decisions, and with what democratic oversight? Are we applying the same criteria consistently, or only when it's convenient?

To close, I want to bring in an image that I think captures the essence of what Popper was saying — beyond all its problems and limitations.

Picture a garden with many different flowers — many colors, many species. That garden is possible precisely because of diversity, because there's space for different forms of life. But for that garden to exist, you have to tend it. You have to pull the weeds. Not because weeds are "bad" in some abstract moral sense, but because if you let them grow unchecked, they end up choking everything else. Diversity doesn't sustain itself. A diverse, flourishing garden requires active work and care.

A tolerant society is exactly like that. Tolerance is not a natural state that sustains itself by doing nothing. It's a historical achievement — fragile and permanently under threat — that requires active work to maintain. It requires institutions, laws, civic culture, and also, when necessary, the willingness to say "this is where it stops."

But the garden metaphor also illustrates the problem the critics raise. Who decides what is a weed and what is an unusual flower we haven't recognized yet? A clumsy or ill-intentioned gardener might pull out exactly the plants the garden most needed to keep.

Karl Popper understood this in the hardest possible way: by losing part of his family in the Holocaust, by fleeing a Europe in flames, and by choosing, despite all of that, to believe in the possibility of building something better. When he sat in New Zealand writing that book, he knew his relatives were dying on the other side of the world. And yet he chose rational argument over bitterness. His words are not those of someone who reasoned coldly in a library. They're the words of someone who had to live the consequences of a society that didn't know where its limits were.

The paradox of tolerance is not a contradiction that can be resolved once and for all. It's a permanent tension, constitutive of any serious democratic project. Living in freedom means coexisting with that tension without resolving it too quickly in either direction. It means rejecting both the naïveté of tolerating everything and the authoritarianism of suppressing everything that makes us uncomfortable.

Can we defend tolerance without becoming what we're fighting against? There's no easy answer. But knowing the question exists — and understanding why it exists — is already an enormous first step.

If this piece made you think, if it generated doubts or an urge to argue, that's exactly the point. Philosophy is not for giving you definitive answers. It's for sharpening the questions. And the questions Popper raises are among the most important we can ask ourselves today.