Wow, that's a boring title. I guess this post is going to be about that somewhat, but it isn't going to be a treatise.
The Massachusetts Department of Education requires that all its schools teach about the Armenian Genocide. What's that you ask? Walk through the Old City of Jerusalem and you'll see the posters all over. It is alleged that during WWI, the Turks embarked on a campaign of extermination against the Armenians, and over one million died.
To date there is a still a dispute over whether those deaths were a result of genocide, with the minority taking the view that they weren't. But the Massachusetts Department of Education does not allow the minority view to be taught in its schools.
So a teacher and high school student decided to bring a suit against the school system on the grounds that such a restriction violates their free speech rights. I'm no scholar but I must have missed the part of Constitution which guarantees teachers the right to teach what they see fit. There are some bounds I'm sure.
But here's the point of the post: Let's say a teacher wanted to teach Holocaust denial. Let's say he passed out the screeds of Zundel or Irving. Could the school stop him? Does they have that right?
I would say yes. Volokh was correct that we should not bar the voicing of opinions that are contrary to our understanding of historical events, even if the case of the Holocaust (at least in the US). But I believe the school system has a right to decide what can be taught in its schools. It's not a free speech right because the government is not stopping the teacher from espousing the views, but only preventing him from doing it in the classroom. I'm sure this issue is more complicated than I make it seem, so let's move on.
When should minority opinions be taught? I would assume most sensible people would have a problem with Holocaust denial or the works of David Duke on slavery. But we can't proscribe every minority opinion. I would draw the line at where the opinion is espoused by a respected person. In the case of history that would mean someone with the requisite training (a Ph.D. if he's really in the minority) and respect within his community. A recognized historian like Raul Hilberg can argue that less than 5 million Jews died in the Holocaust. A drooling lunatic like David Irving, who speaks at neo-Nazi rallies and can't find a Jewish conspiracy he doesn't like cannot. We don't have the time to research every single opinion and we have to draw the line somewhere between legitimate opinion and insanity.