It would make a mockery of truth and academic freedom (it is said) if a university granted Holocaust deniers a platform. But, to begin with, it’s not obvious what exactly is being denied.
Does the Nazi holocaust denote the extermination of European Jewry or all categories of people systematically put to and slated for death? If only Jews, then why? If the criterion is quantitative – fully five-to-six million Jews perished – why then does the Nazi holocaust enjoy a privileged status, such that it can’t be called into question?
Some 30 million Russians were killed during the Second World War, yet no red flags pre-empt free-wheeling debate of this lethal destruction.
Further, if the singularity of the Nazi holocaust and the point at issue resides in the number killed, it’s hard to figure why a taboo would be placed on Holocaust denial. Isn’t the sensible thing simply to present the technical evidence for the widely accepted five-to-six million figure
But maybe it’s the qualitative criterion of how that distinguishes the Nazi extermination: that is, the industrial-style/factory-like/assembly-line process culminating in the gas chambers.
“Not even denial of climate change, which threatens the planet’s very survival, is so sanctioned!”
However, only half of those Jews who died were killed in death camps , while Raul Hilberg, who homed in on the ‘destruction process’ in his monumental study, The Destruction of the European Jews, nonetheless brackets the Nazi holocaust with the Rwandan genocide (‘History had repeated itself’), although the latter was executed utilising the most primitive of weapons .
Still, if the point of contention is the technique, why not then just let the evidence of gas chambers speak for itself? If the intended effect of the taboo on Holocaust denial is to suppress it, the actual effect is to arouse suspicion: why are deniers being muzzled if the evidence incontrovertibly belies their claims?
Indeed, the taboo can boomerang in more ways than one.
The International Holocaust Remembrance Alliance defines Holocaust denial inter alia as, ‘Attempts to blur the responsibility for the establishment of concentration and death camps devised and operated by Nazi Germany by putting blame on other nations or ethnic groups.’ 
Israeli prime minister Benjamin Netanyahu pinned ultimate culpability for the Nazi holocaust on the Palestinian mufti of Jerusalem . Should he be barred from a college classroom?
When teaching John Stuart Mill’s On Liberty, I used to test Mill’s against three hypothetical scenarios, one of which was:
A professor in our history department wants to devote one class of his introductory course on Modern Europe to the proposition that the Nazi holocaust never happened. It is a required lecture course, in which the professor doesn’t field student questions. Should he be permitted to teach this class? 
I first disposed of the obvious demurrals from the class. Doesn’t the professor’s silencing of the class contradict Mill? But, I replied, don’t you listen to radio programs, watch television shows, and read books with which you vehemently disagree yet cannot physically answer? (Indeed, more often than not, the author of an offending text is no longer among the living.)
Do rational people stop up their ears, switch stations, and shred the book, or do they attend to the unwelcome words, regardless of whether they get in the last or even a first word?
Still, the professor’s one-sided presentation (it is said) contradicts Mill.
But, I rejoined, aren’t we bombarded with texts and images – not least in college course offerings – that affirm the Nazi holocaust? It can hardly be deemed a breach of balance if a single professor devotes a single class of a single course to disputing the incessantly-articulated consensus wisdom.
Once having squared away these predictable objections, the real work began.
What’s the point of such a class if I know for certain that the Nazi holocaust happened? But you can’t be certain of your conviction until and unless you’ve heard out and answered any and all objections to it.
Even a child, if their belief is challenged, knows enough of epistemology to retort: Prove me wrong! If they want to hug their certainty, they must first attend to their every naysayer.
‘Complete liberty of contradicting and disproving our opinion is the very condition which justifies us in assuming its truth…; and on no other terms can a being with human faculties have any rational assurance of being right.
‘The beliefs which we have most warrant for have no safeguard to rest on but a standing invitation to the whole world to prove them unfounded.’ (Mill, On Liberty)
Even if you can marshal a mountain of supporting evidence, still, you can’t prefer your belief to that of Holocaust deniers if you refuse even to give them a hearing. The maximum you can rationally claim is agnosticism; otherwise, your belief is based on personal prejudice, not truth.
‘He who knows only his own side of the case knows little of that. His reasons may be good, and no one may have been able to refute them. But if he is equally unable to refute the reasons on the opposite side, if he does not so much as know what they are, he has no ground for preferring either opinion. The rational position for him would be suspension of judgment, and unless he contents himself with that, he is either led by authority or adopts, like the generality of the world, the side to which he feels most inclination.’ (On Liberty) 
Are you all-knowing?
What’s more, even if you don’t harbour doubts, that can’t entitle you to decide for others except if you’re omniscient .
Once having acknowledged your human fallibility, you must also concede the possibility that you’re mistaken, in which case your act of suppression could deny others the possibility of exchanging error for truth.
‘Those who desire to suppress [an opinion], of course, deny its truth; but they are not infallible. They have no authority to decide the question for all mankind and exclude every other person from the means of judging…. All silencing of discussion is an assumption of infallibility.’ (On Liberty)
Even granting the facticity of the Nazi holocaust, giving deniers a platform would still be warranted.
Just as the profundity of ‘all men are created equal’ (another example I invoked to bring home Mill’s point) is not entirely obvious, so the profundity of the Nazi holocaust is not entirely obvious.
If depths of meaning lay buried in it, then, they can only be plumbed in unfettered discussion. It can only be wondered how quick is the reflex to stifle Holocaust denial, even as conjuring taboos will inevitably reduce a human tragedy, however profound, to a sterile mantra, an object of blind worship, or in Mill’s terms, a ‘dead dogma’.
It’s also hard not to miss the proliferation of redlines cordoning off The Holocaust from the corrective of free speech, even – nay, especially - as one of its core postulates appears hollow.
Thus, on the one hand, a unique sanction is imposed on Holocaust denial – not even denial of climate change, which threatens the planet’s very survival, is so sanctioned! – while, on the other hand, demonstrating the uniqueness of the Nazi holocaust has proven elusive and, what’s more, denying its uniqueness, or even juxtaposing it with other historical crimes – except to show that it can’t be compared – is construed as a form of Holocaust denial .
‘[H]owever true it may be, if it is not fully, frequently, and fearlessly discussed, it will be held as a dead dogma, not a living truth.
‘[N]ot only the grounds of the opinion are forgotten in the absence of discussion, but too often the meaning of the opinion itself. The words which convey it cease to suggest ideas, or suggest only a small portion of those they were originally employed to communicate. Instead of a vivid conception and a living belief, there remain only a few phrases retained by rote; or, if any part, the shell and husk only of the meaning is retained, the finer essence being lost.’ (On Liberty)
The more the taboos multiply, the more the Nazi holocaust is unmoored from time and space and is reduced to an object of idolatry.
Haven’t the taboos enveloping the Nazi holocaust – the fear of questioning (facets of) it, the sacrosanct status it occupies – not only caused it to calcify into a lifeless ritual, but also spawned a raft of spurious testimonial literature and preposterous pseudo-scholarship, the paradoxical outcome of which is to provide fodder for the deniers’ mills? 
If a purported witness enjoys immunity from cross-examination – as does every Tom, Dick and Moishe pawning himself off as a ‘Holocaust survivor’  – the human propensity is to exaggerate, which, if left unchecked, will harden into a lie.
‘[T]here is always hope when people are forced to listen to both sides; it is when they attend only to one that errors harden into prejudices, and truth itself ceases to have the effect of truth by being exaggerated into falsehood.’ (On Liberty)
It’s also possible (even probable) to get the big picture right yet some of the constituting facts wrong.
If one is committed to the purity of truth, not just in its wholeness but also in its parts, then Holocaust deniers perform the useful function of ferreting out ‘local’ errors, precisely because they are devil’s advocates – that is, fanatically committed to ‘unmasking’ the ‘hoax of the 20th century’.
Deniers consequently invest the whole of their being in scrutinising every piece of evidence, not taking the tiniest detail for granted, passing a fine-tooth comb through each one, and, in their monomaniacal zeal to expose an error, inevitably unearthing one.
‘[E]ven if the world is in the right, it is always probable that dissentients have something worth hearing to say for themselves, and that truth would lose something by their silence.’ (On Liberty) 
‘If these people want to speak, let them,’ Hilberg counselled. ‘It only leads those of us who do research to re-examine what we might have considered as obvious. And that’s useful.’  (Hilberg privately noted that it was Holocaust deniers who demonstrated that Zyklon-B in its unalloyed form was not sufficiently lethal to have been used in the gas chambers.)
If he was laid back when it came to Holocaust deniers, it’s because Hilberg was confident in his conclusions based on his mastery of the source material.
The impulse to suppress springs not only from disgust at what Holocaust deniers outrageously proclaim but also, and more often, from dread of the inability to credibly answer them. 
‘Yes, there was a Holocaust,’ Hilberg once observed, ‘which is, by the way, more easily said than demonstrated.’  If you’ve done your homework, then fielding obnoxious skeptics is at worst a form of intellectual amusement, the mental equivalent of shooting fish in a barrel. (I vividly recall my own deflated sense of intellectual self upon perusing Holocaust-denier Arthur Butz’s The Hoax of the 20th Century. He correctly observed, for example, that it was originally alleged that three million Jews were killed at Auschwitz, and six million Jews altogether were killed. The figure for the number killed at Auschwitz was subsequently scaled down to one million, yet the total figure was still put at six million. How can this be?, Butz rhetorically asked. I had no answer.)
The upshot is, by placing under a microscope and inspecting from every angle each scrap of evidence, the Holocaust denier is doing for you what you, if you are genuinely committed to truth, would have to do for yourself; the difference being, the denier’s is the more thoroughgoing inspection because it’s much harder to argue against yourself once you’ve settled into or developed a vested interest in your belief.
Thus, far from suppressing Holocaust deniers, one should be grateful to them for – however unintentionally – facilitating the quest for truth.
‘Nor is it enough that he should hear the arguments of adversaries from his own teachers, presented as they state them, and accompanied by what they offer as refutations. That is not the way to do justice to the arguments, or bring them into real contact with his own mind.
‘He must be able to hear them from persons who actually believe them; who defend them in earnest, and do their very utmost for them. He must know them in their most plausible and persuasive form; he must feel the whole force of the difficulty which the true view of the subject has to encounter and dispose of; else he will never really possess himself of the portion of truth which meets and removes that difficulty.
‘If there are any persons who contest a received opinion, or who will do so if law or opinion will let them, let us thank them for it, open our minds to listen to them, and rejoice that there is someone to do for us what we otherwise ought, if we have any regard for either the certainty or the vitality of our convictions, to do with much greater labor for ourselves.’ (On Liberty)
The obvious caveat to the Millian argument is: it’s well and good to let Holocaust deniers ply their trade undisturbed in the public arena, and even to tolerate them as speakers should a campus organization elect to invite them, but doesn’t a different set of rules apply to the classroom?
Just as one’s peers must vet the scholarly merit of texts submitted for publication (otherwise academia degenerates into a haphazard free-for-all), so a history department must vet its course offerings: economies of time preclude inspecting a critical historical event from every possible angle.
How can it be justified to squander even one class of one course on a quack proposition?
It’s surely legitimate to debate whether the US Civil War was fought over states’ rights or slavery, or whether chattel slavery is better or worse than wage slavery.
Likewise, many basic questions regarding the Final Solution have not yet been resolved; indeed, controversy still swirls around when it began and why Hitler implemented it.
But wouldn’t debating whether or not it happened be as frivolous as debating whether or not slavery existed in the South of the United States before the Civil War? Cast thusly, the question answers itself.
What is the danger?
However, there’s a critical difference. Those declaiming against the virtue of ‘balance’ – in other words, presenting all sides to a proposition in the classroom – and gesturing to Holocaust denial as proof positive that balance is absurd, simultaneously allege that Holocaust denial constitutes an incipient or even imminent danger in society.
But if it poses so grave a threat among the general population , how else can it be dislodged except by directly confronting it, not in a straw-man version (its refutation won’t persuade), but in its most virulent version espoused by the devil’s advocate?
“If Holocaust denial does constitute an actual or potential contagion then it should be taught, ideally by Holocaust deniers, if only to inoculate students.”
The answer surely can’t be to suppress Holocaust denial by resort to censorship or force majeure. The purpose of a university is the search for truth, not the imposition of ‘correct’ ideas.
It’s also nearly impossible to physically stamp out an ‘incorrect’ idea, while, once gaining traction, it will spread with ease among a population ignorant of the arguments against it and consequently mentally disarmed to counter it.
‘[T]o shut out discussion entirely is seldom possible, and when it once gets in, beliefs not ground on conviction are apt to give way before the slightest semblance of an argument.’ (On Liberty) 
If, for argument’s sake, it is set aside that, first, Holocaust denial can’t be suppressed if ‘The Holocaust’ doesn’t denote a stable, discrete object, and, second, that Holocaust denial largely comprises discrete factual assertions that can be disposed of with discrete factual rebuttals, then, the bottom line is this.
If Holocaust denial is a marginal phenomenon, then, in light of a faculty’s responsibility to familiarize students, not with every last word on a subject, but only with ‘the best published expressions of…the questions at issue,’  it arguably shouldn’t be taught in a college classroom because it doesn’t figure in current academic debates on the genesis and contours of the Nazi holocaust, although deniers do perform, albeit inadvertently, a valuable function in society at large, such that it would hamper the pursuit of truth to suppress them altogether.
If, however, Holocaust denial does constitute an actual or potential contagion then it should be taught, ideally by Holocaust deniers, if only to inoculate students.
To profess both that Holocaust denial shouldn’t be taught and that it poses a clear and present danger defies logic.
The claim by Facebook CEO Mark Zuckerberg and Twitter CEO Jack Dorsey that an alleged global rise in anti-Semitism and ignorance of the Nazi holocaust justify suppression of Holocaust denial no less lacks in logic.
 Fully a quarter were just lined up and shot dead in killing fields.
 Raul Hilberg, The Destruction of the European Jews, third edition (New Haven: 2003), vol. 3, pp. 1294-96.
 https://www.holocaustremembrance.com/working-definition-holocaust-denial-and-distortion. This definition of Holocaust denial comprises five taboos. The other four are “Intentional efforts to excuse or minimize the impact of the Holocaust or its principal elements, including collaborators and allies of Nazi Germany”;“Gross minimization of the number of the victims of the Holocaust in contradiction to reliable sources”;“Attempts to blame the Jews for causing their own genocide”; “Statements that cast the Holocaust as a positive historical event.”
 “Netanyahu: Hitler didn’t want to exterminate the Jews,” Haaretz (21 October 2015).
 The other two scenarios were: A professor in our biology department wants to devote one class of her course in Genetics to the proposition that people of color are intellectually inferior to white people; A professor in our anthropology department wants to devote one class of his course in Comparative Culture to the proposition that in some cultures women enjoy being beaten and raped. While teaching in Turkey, I replaced the Holocaust denier scenario with: A teacher in the religion department wants to devote one class of his course on Comparative Religion to the proposition that Islam is a terrorist religion.
 I would make the analogy with a customer telling a Baskin-Robbins employee that vanilla is his favorite flavor. “But have you tasted the other 30 flavors?” “I don’t need to. I love vanilla. It’s soft, it’s sweet, it’s creamy, it’s got that tingly feeling.” “Your reasons may be excellent, sir, but if you haven’t so much as tasted the other flavors, how can you prefer vanilla?”
 I would playfully query the student proclaiming certainty, “Are you God?”
 Norman G. Finkelstein, The Holocaust Industry: Reflections on the exploitation of Jewish suffering, second edition (New York: 2003), pp. 41-55.
 Finkelstein, Holocaust Industry, pp. 55-78. A fuller explanation would take account of the ideological utility that gives this nonsense currency (see ibid.).
 Ibid., pp. 158-61, 236-39.
 I would liken it in class to the aesthetic incompleteness of a mosaic when one tile is missing, a jigsaw puzzle when one piece is missing, or a crossword puzzle when one letter is missing. Just as mathematicians speak of an “elegant” proof, so truth has its own aesthetic that is flawlessness.
 Christopher Hitchens, “Hitler’s Ghost,” Vanity Fair (June 1996). Hilberg privately noted that it was Holocaust deniers who demonstrated that Zyklon-B in its unalloyed form was not sufficiently lethal to have been used in the gas chambers.
 “The silencing of an opponent,” a modern-day disciple of Mill noted, “sounds alarmingly like an admission that we cannot answer him.” Conrad Russell, Academic Freedom (New York: 1993), p. 44.
 “Is There a New Anti-Semitism? A conversation with Raul Hilberg,” Logos (Winter-Spring 2007; http://www.logosjournal.com/issue_6.1-2/hilberg.htm).
 In fact, the danger is largely contrived (Finkelstein, Holocaust Industry, pp. 68-71), but that’s a separate issue. I am addressing here the argument of those who invoke Holocaust denial to clinch the case against balance, yet who also allege that Holocaust denial poses a clear and present danger.
 I used to make the analogy with Germany’s ban on the publication of Mein Kampf: were it truly committed to preventing a resurgence of Nazism, Germany would, on the contrary, make critical study of Mein Kampf mandatory.
 American Association of University Professors 1915 statement; emphasis added.