Karl Popper wrote one of the most widely shared philosophical texts on the internet. It is also one of the most consistently misread.

The argument is simple on its surface: a society that tolerates intolerant movements — movements explicitly committed to destroying the conditions of tolerance itself — is not practicing tolerance. It is providing the conditions for tolerance's own destruction. Unlimited tolerance is self-defeating.

Most people who share the Popper quote stop there. What they almost never include is what he wrote next: that suppression should be a last resort only when rational argument has definitively failed and that the threshold for restricting a movement is not that its ideas are offensive or wrong, but that it has abandoned rational discourse entirely in favor of violence.

That qualification changes everythi ...