The slippery slope fallacy is "this is the first step, and further steps will be easier, so we shouldn't take that step". Sometimes that is true, often it is no

The slippery slope fallacy is "this is the first step, and further steps will be easier, so we shouldn't take that step". Sometimes that is true, often it is not. Free speech is a category where there really does seem to be a slippery slope. Infrastructure built to combat child pornography is now used to block porn in general in the UK, for instance. In the US, it's used to block sites infringing copyright. If that first step hadn't been taken - if providers hadn't been required to build that infrastructure for CP - it would have been far more difficult to force them to create it for porn or piracy. But once "filter things we don't like" was accepted, expanding the list of disliked things was far easier than setting up the filter in the first place. As for tolerating intolerance - I personally always find it depressing when people use this to advocate for silencing Nazis, or white supremacists, or racists, or people that happen to be called those things. Here's a more complete quote of Popper: > Less well known is the paradox of tolerance: 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.—In this formulation, 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 by public opinion, suppression would certainly be most unwise. But we should claim the right to suppress them if necessary even by force; for it may easily turn out that they are not prepared to meet us on the level of rational argument, but begin by denouncing all argument; they may forbid their followers to listen to rational argument, because it is deceptive, and teach them to answer arguments by the use of their fists or pistols. We should therefore claim, in the name of tolerance, the right not to tolerate the intolerant. Nazis, despite what many seem to think, do NOT have the power to suppress speech with violence in the US, or Germany, or anywhere else. Popular opinion is also firmly against such philosophies. But there IS a philosophy in the US that fits the latter part of his description - one that is not prepared to meet others in a rational argument, and instead denounces all argument. One that responds to speech they do not like with force aimed to silence that speech. And yes, one that encourages the use of physical force as well. What else is "Punch a Nazi", if not responding to speech with force? You won't see Visa blacklisting them anytime soon though, because they ARE Visa. And Mastercard. And numerous other organizations across the world. That doesn't mean that it's a good thing.