Paradox of tolerance
A Socratic walk-through of the paradox of tolerance — reasoned out one step at a time, not lectured.
The question we started with
THE QUESTION #Why must a society committed to tolerating everything refuse to tolerate at least one thing?
Take tolerance seriously enough and it looks like it should have no exceptions. The moment you start listing views too dangerous to permit, you have conceded that somebody holds the list, and that somebody will not always be you.
Now notice what an exceptionless rule promises: protection to a movement whose declared aim is to abolish the protection, which can use every liberty the rule grants it right up to the day it no longer needs them. The rule appears to guarantee its own abolition in proportion to how faithfully it is kept. Is that a paradox, or is something in the setup wrong?
Reasoning it through
REASONING #Karl Popper gave the argument its name in a footnote to The Open Society and Its Enemies in 1945 — a footnote is what it is, one of a family he drew alongside the paradox of freedom and the paradox of democracy, all sharing one shape: an unlimited principle supplying the means of its own defeat.
Start with the loop, because the loop is the engine. Tolerance is not a substance a society holds; it is a standing disposition of institutions and of the people who staff them. That disposition is what protects the intolerant movement, and if the movement wins, the disposition is what it dismantles. The norm's output feeds back into the conditions for the norm's survival, with a negative sign. Any such rule has a stability question.
But a stability question is not yet a licence, and here the popular use of the phrase parts company with Popper. He does not imply, he writes, 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 by public opinion, suppression would be most unwise. What we should claim is the right to suppress them if necessary, because they may not be prepared to meet us on the level of rational argument, and may instead denounce all argument, forbid their followers to listen to it, and answer arguments with fists.
So the condition is not "this doctrine is intolerant." It is that argument has stopped being possible — the movement has left the space where refutation could reach it. He goes further than modern quoters expect in one direction, saying incitement to intolerance should be criminal in the way incitement to murder is, and much further in the other, holding suppression unwise while argument and public opinion still work. The version that circulates online — tolerance as a contract you breach by being intolerant, forfeiting your protection — drops both trigger and restraint, turning a narrow emergency claim into a general permission. John Rawls reached the same condition by another road in A Theory of Justice: an intolerant sect has no title to complain when denied liberty, but the tolerant should not curtail its freedom unless they sincerely and with reason believe their own security and the institutions of liberty are in danger.
Is any of this empirical? Part of it. That tolerating an intolerant movement leads to tolerance's destruction is a causal claim about societies, and the two big legal systems ran the experiment in opposite directions. Germany's post-war constitution allows parties to be banned, and its Federal Constitutional Court banned the neo-Nazi SRP in 1952 and the Communist KPD in 1956, while in 2017 it declined to ban the NPD, finding its aims unconstitutional but its prospects of achieving them insufficient. The United States went the other way in Brandenburg v. Ohio in 1969, protecting even advocacy of violence unless it is directed to inciting imminent lawless action and is likely to produce it. The falsification test: if unlimited legal tolerance really does destroy tolerance, the permissive system should show erosion the restrictive one does not. Neither record is clean, and whether bans shrink a movement or supply it with martyrs is genuinely contested — which is why I will not tell you the answer.
The analogy
THE ANALOGY #Think of the immune system's tolerance of the body's own cells. It has to be near-total, or the body attacks itself — yet a pathogen that succeeds by presenting itself as self-tissue is admitted precisely by the mechanism working correctly. Defence cannot mean becoming less tolerant in general; it means a specific test for the one case where admission would end the ability to admit anything.
an immune system has no fallible judge and no politics, whereas the whole difficulty here is that the test must be applied by the people currently in power, who have every incentive to read their opponents into it.
Clarifying the model
THE MODEL #The most common misreading is that Popper offered a rule of the form "intolerance forfeits protection." He did not. He offered a right held in reserve, triggered when the ordinary corrective — argument answered by argument — has been withdrawn by one side. The distinction matters because that trigger is checkable in a way "this view is intolerant" is not: you can point to a movement's declared refusal to be answered.
It also helps to see what kind of paradox this is. It is not a contradiction in the concept of tolerance but an instability in the unrestricted version of the norm. That distinguishes it from the self-defeating aims elsewhere in this collection — sleep, spontaneity, happiness — where the pursuit is itself an ingredient that spoils the state. Nothing psychological is going on here: the mechanism is external and political, an unlimited norm licensing agents who will remove it. The fixed point of difference is that self-defeating aims fail inside one mind, while this one fails only because someone else is willing to exploit the rule.
And no formulation removes the cost of the exception. Any workable version needs an authority to decide when the trigger has been pulled, and that authority is the institution the intolerant movement wants to capture. Popper, the fiercest of fallibilists, knew it; the argument is not that suppression is safe, only that unlimited tolerance is not safe either, and that pretending otherwise is a choice rather than a neutrality.
A picture of it
THE PICTURE #How to readStart at Argued, the ordinary condition in which an intolerant doctrine is tolerated and refuted in public. Each arrow is a change in the movement's own conduct, not in how offensive its content is. The only route Popper licenses to Suppressed runs through Closed, the state in which the movement has stopped being reachable by argument at all — and the return arrows matter as much, since suppression is meant to lapse when that condition does. The bottom edge is the misreading: a jump straight from tolerated to suppressed on the strength of the doctrine's content, skipping the test that does all the justifying work.
What became clearer
WHAT CLEARED #The paradox is real but narrow. An unlimited tolerance norm has a feedback loop that can end it, so some limit is unavoidable — yet the limit Popper defended is a reserved right, triggered by a movement's refusal to be answered rather than by the offensiveness of what it says, and not to be used while argument still works. The popular version keeps the conclusion and discards the condition, converting a claim about emergencies into a general licence and handing it to whoever holds the microphone.
Where to go next
ONWARD #- Militant democracy in practice: what constitutions permitting party bans require before one is granted.
- Whether "no platform" norms enforced privately raise the same problem, absent state coercion.
Key terms
TERMS #| Term | What it means |
|---|---|
| Paradox of tolerance | Popper's observation that unlimited tolerance tends to destroy tolerance, since it protects those who would abolish it. |
| Militant democracy | the principle that a democratic order may restrict anti-democratic actors to preserve itself; the term is Karl Loewenstein's, from the 1930s. |
Every term the collection defines is gathered in the glossary.