> What does it matter if somebody genuinely holds heinous views? So long as they are willing to discuss things logically, cool-headedly, and coherently --- I'd be happy to discuss anything with anybody.

So, it sounds like what you're saying here is that if Alice says to Bob, "I think you're fundamentally subhuman; you have no value as a person, and I think that you don't deserve the same human rights that I do" and Bob replies, "That's a disgusting viewpoint and you're a disgusting person for having it", you feel like Bob is in the wrong because Bob is getting emotional while Alice is being logical, cool-headed, and coherent. This is a weird viewpoint because being able to express something logically doesn't necessarily make you more right or better than the other side; see the comic[1] where an angry person is shouting "Raarg people deserve to be treated like humans nobody has the right to murder millions hurr" and the calm, collected Hitler is saying "I just want to murder all the Jews and take over the world, but that's your opinion and I'm fine with that. Looks like you've got some growing up to do"

If you haven't picked up on it yet, the idea that I'm trying to express here is that even if something can be expressed logically, that doesn't mean it deserves a platform for logical debate. Murdering all the Jews is a _bad position_, no matter how you express it. If your position is that it might be a good thing to murder all the Jews, trying to debate with you logically about why it is bad can only serve to legitimize what is unlegitimate. If you don't accept the premise that murdering people for being Jews is bad, I'm not going to convince you that it's good. And if I'm a Jew, I might get a little worked up about the idea that you think murdering me is a viable path towards improving the world. This is not an indication that I'm bad or that I'm arguing in bad faith; it means that I take poorly to the idea of being murdered arbitrarily. Similarly, when somebody expresses the idea that black people are subhuman trash and deserve to be shot in the streets by police because they are no different from monkeys, it's not really going to be that easy to convince them that actually, people are people and deserve to be treated as such. If I'm black and being called a monkey, that's not really an invitation to a fair and open debate, right? Your position is couched in the idea that I'm not even worth debating with, because I'm subhuman.

Additionally, it's very rare that people _hold_ heinous viewpoints but never _act_ on them. Even if all you do is express your heinous viewpoints, that has the effect of normalizing those heinous viewpoints for other people; consider the recent event where a popular Youtuber (Pewdiepie) called somebody a "nigger" in an online game; part of his defense for his actions was that it's a common thing and everybody does it. Calling out the holding (and expressing) of heinous viewpoints is an important part of helping the rest of society move past those viewpoints. If I make it clear that it's not okay to call people niggers as a joke, then maybe people will stop saying it as a joke. And if people stop saying it as a joke, then the people who are saying it for real won't have the legitimizing cloak of 'irony' (think "come on, dude, I was only joking, don't get so mad!") and will be shows as the actual racists they are.

[1]: http://i0.kym-cdn.com/photos/images/original/000/578/682/575...