I think that anti-Semitism is a qualitatively distinct form of racism which ought to be considered on the borderline of mental illness. I'll admit fault for calling it a mental illness without qualification.
Let's be clear we're talking about the same thing here. The definitions for mental illness that I'm familiar with say that mental illness must be something that is not widespread in the person's culture, a beliefs or behavior that others consider weird or irrational. People imitate and conform to other's beliefs and actions so much, that anything that is common to a large segment of the population (e.g. religious belief) cannot be usefully called a mental illness. Anti-Semitism clearly fails this test.
Anti-Semitism is not only racial but also religious and nationalist, and it can happen anywhere.
Hating outgroups based on religious and nationalist lines, is just as normal and widespread as on racial lines. Almost every multi-religious society has or had in the past a large degree of segregation, distrust, and perhaps sectarian violence. The same goes for populations of "mixed nationalities".
Since the Jews historically lived among people where they were at once a religious, racial, and (in the last century) nationalist outgroup, it is not at all surprising that they were hated. Just like, since U.S. blacks are mostly a distinct social class from whites, and were previously a legally distinct class too, it's natural for this distinction to merge with the racial hatred and make it stronger.
We use a special term, anti-Semitism, because of the its historical importance, but it doesn't seem to me to be qualitatively different from other kinds of inter-group hatred.
Garden-variety racists are not typically racialists with a well-constructed theory to support their bigotry, but anti-Semites almost always are.
This has only stood out since the 19th century in Europe. (Previously, other societies concerned themselves with racial purity and descendants of Jews, like Christian Spain; but they were the exception, not the rule.)
Yet Anti-Semitism has existed as long as mainstream Christianity. (And probably before - I just don't happen to know anything about the integration or otherwise of Jews in the Roman and Greek worlds.) Anti-Semitism changed a little in character when racial theories were added to the mix, but the so-called "modern" A-S could not have existed (in such a magnitude) with the millenia of "classic" A-S preceding it.
Conspiracies about Chinese and Japanese subterfuge wax and wane, but anti-Semitism stays. Jews are blamed simultaneously for the worst excesses of capitalism and socialism, for the kidnap and murder of children for ritual, food, and sport. They are out to undermine the true religion and dilute the blood of the best races, and turn the nations into beggars.
I would like to see a quantitative survey of the equivalent of blood libels in other famous sectarian hatreds. I would expect to find out that Christians have told (and tell) just as bad tales about Muslims, Protestants about Catholics, US whites about blacks, as anyone has told about Jews.
Also, A-S tales are famous in our culture. Mostly everyone has heard of the Blood Libel and the Protocols of the Elders of Zion. Maybe we just haven't heard enough non-A-S examples, and so A-S has become highly available to our thinking.
I still disagree, but kudos for a very reasonable response. May I plead time constraints in the hope that we may revisit this topic later?
LessWrong has been having fun lately with posts about sexism, racism, and academic openness. And here just like everywhere else, somebody inevitably claims taboo status for any number of entirely obvious truths, e.g. "top level mathematicians and physicists are almost invariably male," "black people have lower IQ scores than white people," and "black people are statistically more criminal than whites." In my experience, these are not actually taboo, and I think my experience is generalizable. I'll illustrate.
You're at a bar and you meet a fellow named Bill. Bill's a nice guy, but somehow the conversation strayed Hitler-game style to World War II. Bill thinks the war was avoidable. Bill thinks the Holocaust would not have happened were it not for the war, and that some of the Holocaust was a reaction to actual Jewish subterfuge and abuse. Bill thinks that the Holocaust was not an essential, early plan of the Nazis, because it only happened after the war began. Bill thinks that the number of casualties has been overestimated. Bill claims that Allied abuses, e.g. the bombing of Dresden, have been glossed over and ignored, while fantastic lies about Jews being systematically turned into soap have propagated. Bill thinks that the Holocaust has become a sort of national religion, abused by self-interested Jews and defenders of Zionist foreign policy, and that the freedom of those who doubt it is under serious attack. Bill starts listing other things he's not allowed to say. Bill doesn't think that the end of slavery was all that good for "the blacks," and that the negatives of busing and forced integration have often outweighed the positives. Bill has personally been the victim of black-on-white crimes and racism. Bill is a hereditarian. Bill doesn't think that dropping an n-bomb should ruin a public career.
Here's the problem: everything Bill has said is either true, a matter of serious debate, or otherwise a matter of high likelihood and reasonableness. Yet you feel nervous. Perhaps you're upset. That's the power of taboo, right? Society is punishing truth-telling! First they came for the realists... Rationalists, to arms!
Or.
We can recognize that statements like these correlate with certain false beliefs and nasty sentiments of the sort that actually are taboo. It's just like when somebody says, "well science doesn't know everything." To this, I think, "duh, and you're probably a creationist or medical quack or something similarly credible." Or when somebody says, "the government lies to us." To this, I think, "obviously, and you're likely a Truther or something." Bill is probably an anti-Semite, but Bill doesn't just say, "I'm an anti-Semite," because that really is taboo. He might even believe that he shouldn't be considered something awful like an anti-Semite. Bill probably doesn't think Bill so unpleasant.
That's the paradox: "taboo" statements like black crime statistics are to some extent "taboo" for sound, rationalist reasons. But "taboo" is not taboo: it's about context. People who think that such statements are taboo are probably bad at communicating, and people often think they're racists and misogynists because they probably are on good rationalist grounds. If you want to talk about statistical representatives on the topic of race, be ready to understand that those who are listening will have background knowledge about the other views you might hold.
All this is the leadup to my question: what highly probable or effectively certain truths are genuinely taboo? I'm trying to avoid answers like "there are fewer women in mathematics" or "the size of my penis," since these are context sensitive, but not really taboo within a reasonable range of circumstances. I'm also not particularly interested in value commitments or ideologies. Yes, employers will punish labor organizers and radical political views can get you filtered. But these aren't clear matters of fact. I also don't mean sensitive topics like abortion or religion, nor do I mean "taboo within a political party."
Is there really anything true that we simply cannot say? I have the US in mind especially, but I'm interested in other countries as well. I'm sure there are things that deserve the label, but I've found that the most frequently given examples don't hold water. I think hereditarianism is a close contender, but it's not an "obvious truth." Rather, my understanding is that it is a serious position. It's also only contextually taboo. If it were a definitive finding, it could perhaps become taboo, though I think it more likely that it would be somewhat reluctantly accepted.
Any suggestions? If we find some really serious examples, we might figure out a way to talk about them.