Holocaust Denial Follows the Same Playbook as Pseudoscience

"The SS loved to tell us that we had no chance of escaping alive, a point they delighted in emphasizing, insisting that after the war the rest of the world would never believe what had happened; there would only be rumors, speculation, but no irrefutable evidence, and everyone would conclude that such evil on that scale was simply impossible.”
— Terence des Pres, The Survivor, cited in Denying History by Michael Shermer and Alex Grobman

My most vivid memory of visiting Yad Vashem, Israel’s Holocaust Museum, is not of the horrifying photos of concentration camps or the emotional testimonies of survivors—though, of course, those left deep scars. What marked me most was seeing my father, as we exited the museum, crying uncontrollably, like a child. I was 11 years old and didn’t yet understand that for him, beyond the horrors of war and imagining the uncles, cousins, and grandparents he never met in those photos, there was also the crushing weight of survivor’s guilt.

My grandfather had lived in Berlin in the 1930s, long enough to feel the growing antisemitism firsthand. His father—my great-grandfather—refused to believe there would be war or danger for Jews. “This will pass,” he said. “It’s just a fad. Jews have always lived peacefully in Germany.” By the time the family realized the inevitable, it was too late. My grandfather escaped to Brazil. The rest of the family perished.

My father grew up without knowing his grandparents, uncles, or cousins. My grandfather carried survivor’s guilt in the letters he received—until one day, they stopped coming. At night, he would read them and cry. My grandmother, weary of the anguish, threw them all away after his death.

Perhaps she would have kept those letters had she known that, just a few generations later, organized political groups and antisemites would try to claim the Holocaust never happened. At first glance, Holocaust denial seems as absurd as flat-Earth theory. Who, in their right mind, could deny one of the best-documented events in human history, with hundreds of thousands of living witnesses? But just like science denial, history denial is a perverse art. It distorts facts, minimizes significance, and the consequences can be dire. That is why denial must be taken seriously and confronted.

What do deniers claim?

There are two main forms of Holocaust denial. Some argue the massacre never occurred—that the six million figure was fabricated by Jews to justify the creation of Israel. Others admit antisemitism existed, that concentration camps were real, but claim these were merely labor camps, not extermination centers, and that deaths were the “natural” result of war, disease, or starvation. They reduce the number of victims to between 300,000 and one million.

Like pseudoscience, Holocaust denial relies on twisting isolated facts. For example: not all camps had gas chambers—so, they claim, there was no extermination plan. Zyklon-B, the gas most often used, was also a disinfectant—so it wasn’t “meant” for humans. Or they fixate on a confession by Rudolf Höss, Auschwitz’s commandant, who said guards smoked cigarettes while removing bodies just ten minutes after gassing. “But Zyklon-B is flammable,” deniers argue, “so the confession must be false, and the gas chambers never existed.”

What they omit is context. Zyklon-B’s flammability depends on concentration. In the parts per million used in exterminations, with Nazi-installed ventilation systems dispersing the gas afterward, there was no explosion risk. Similarly, dismissing the Holocaust because some camps lacked gas chambers ignores other methods of mass killing, like shootings and lethal injections.

The strategy is always the same: isolate a fact, strip it of context, distort it, and generalize. It’s identical to tactics used in pseudoscience, like Intelligent Design advocates who claim evolution is false because one bacterial structure seems “irreducibly complex”—ignoring that science has already explained it.

How do we know the Holocaust happened?

Unlike deniers suggest, history is not built from scattered anecdotes. It rests on a convergence of evidence that points to one conclusion: Nazi Germany carried out an industrial-scale extermination plan, murdering over six million defenseless people.

Michael Shermer and Alex Grobman, in Denying History, summarize this convergence:

Documents: letters, memos, military orders, speeches, memoirs, confessions.

Testimonies: survivors; Sonderkommando Jews forced to operate gas chambers and dispose of bodies; SS soldiers; Nazi commanders; local residents who witnessed deportations.

Diaries: six written by Sonderkommando members, detailing the gas chambers’ operations.

Photographs: official military records, clandestine images by prisoners, aerial photos, and German soldiers’ snapshots.

The camps themselves: concentration, labor, and extermination sites still standing.

Demographics: six million Jews disappeared from Europe’s population—where did they go, if not killed?

Historian Deborah Lipstadt poses a thought experiment: for deniers to be right, who must be wrong? Survivors—who must all be liars in some vast Zionist conspiracy. Local witnesses—who must have imagined their neighbors vanishing into trains. And even the Nazis themselves—who never denied the killings, but rather excused themselves with “just following orders.”

Why fight denial?

Pseudo-history, like pseudoscience, is dangerous. Left unchallenged, lies grow. With time, memory fades.

Seventy-five years after Auschwitz was liberated, denial thrives in the shadows of conspiracy theories, academic façades, and extremist groups. Just as pseudoscience hides behind fake journals and institutes, Holocaust denial cloaks antisemitism under the guise of “research.” We cannot be fooled: to deny or minimize the Holocaust is antisemitism, plain and simple.

“Never forget” is the motto of International Holocaust Remembrance Day, marked every January 27, the day Auschwitz was liberated. I remember my grandfather weeping over letters from family lost in the war, and I recall a comic strip I once read:

A child asks her grandfather, “Grandpa, if it hurts so much to look at these photos and tell these stories, why do you do it?”
Through tears, he answers: “So that you will not forget.”

✍️ Natalia Pasternak is a researcher at the Institute of Biomedical Sciences (ICB) at USP and president of the Instituto Questão de Ciência.