I reject the claim that giving people exactly the kind of society they want (e.g. one which puts dangerous people into concentration camps) is merely "repeating

I reject the claim that giving people exactly the kind of society they want (e.g. one which puts dangerous people into concentration camps) is merely "repeating the cycle". That is the rallying cry of those who do evil and then declare, "you can't punish me because that would be hypocritical!" "Do unto others as they publicly declare they want done unto society" does not continue any cycles. You can't apply the rule a second time and say, "well you put people into camps therefore you go into a camp", because the rule doesn't say "do unto others as they did unto you", but rather looks at what they advocated for. I wouldn't advocate for putting random "dangerous people" into camps; I only advocate for doing this to those who publicly declare it is to be done. What's unique about this rule is that I will more than happily submit to your application of it to me: because what that means is you will put me into the kind of society for which I advocate. That's exactly what I want! Everyone applying this rule isn't an eye for an eye as you imply; but rather a utopia where everyone lives in exactly the society he wants to live in. More realistic variants of this - can we curtail the free speech of those who campaign against free speech? I say yes. Can we declare to be thoughtcrime illiberal ideologies? Yes. A society which says, "anything is permitted, except explicit campaigns against this founding principle", is much more free in the long run than a society which permits itself to be co-opted by an opposite ideology.