Contrary to what one might expect, the central question raised by the all-over-the-map documentary “The Meaning of Hitler” is not “Can Hitler happen here, and now?”

That was an interesting premise for academic debate in 1966. Not today. The Unite the Right rally in Charlottesville in 2017, along with countless other recent incidents, proves that white nationalism is a clear and vivid threat.

Rather, the query posed here, in different ways by various learned experts in numerous countries, is “What good are the lessons of history if a large number of people don’t know, deny, ignore, bury, erase, misrepresent or lie about the underlying history?”

This is not a new idea for those, like historian Deborah Lipstadt, who’ve been confronting antisemitic Holocaust denial for decades. The contemporary impetus for “The Meaning of Hitler,” which was filmed before the pandemic, is unambiguous: The existential and actual threat of the demagogue former president, Donald Trump.

The timing and goals of this film are unassailable. If its approach is scattershot, well, it still allows for the collection of a large number of ideas and insights.

“The Meaning of Hitler” opens Friday on demand on IFC, and in theaters in New York and Los Angeles.

English novelist Martin Amis, whose pithy observations run through the film, sets the tone early. “Our understanding of Hitler is central to our self-understanding,” he says. “It’s a reckoning you have to make, if you’re a serious person.”

Veteran filmmaking couple Michael Tucker (an American) and Petra Epperlein (a German) take the late German journalist and historian Sebastian Haffner’s eponymous 1978 book as their jumping-off point for revisiting elements of Hitler’s biography and appeal, and the methods and madness of the Nazi regime.

At the same time, using clips from long-forgotten films from Hollywood and Europe, the filmmakers aim to shine a withering light on the lingering mythic aspects of the Third Reich — without adding to it themselves.

A visit to Hitler’s childhood home in Austria and the site of his World War I battlefield experience in Flanders proves prosaic, but Tucker and Epperlein score an oddball hit at the U.S. Army Center of Military History, where four of Hitler’s watercolors dating to 1910 are stored.

The filmmakers are careful to provide Nazi-era facts at every turn, especially on the occasions they give a bit of screen time to dissemblers, deniers and anti-immigrationists such as the repugnant David Irving (accompanied on a visit to Treblinka, of all places). But others in the film, including historian Saul Friedlander and Nazi hunters Serge and Beate Klarsfeld, are cognizant that they are speaking to reality-based viewers who don’t need to be sold on the actuality of the Shoah.

Lipstadt realizes it, too, but that doesn’t stop her from speaking bluntly. “If this history [the Holocaust] can be rewritten,” she declares, “any history can be rewritten.”

So how, as ever, to reach the accidentally ignorant, the willfully uninformed and the opportunistically misled? How to combat the propaganda tactics perfected by Hitler and appropriated by current wannabe fascists?

At Friedlander’s suggestion, the filmmakers discover a possible answer at Sobibor. In a quiet, bird-less forest, an archaeologist describes how Hitler demolished and buried the death camp after the successful prisoner revolt of 1943.

This shameless attempt to erase the Nazis’ crimes, by planting over them, succeeded for a while. But not forever. There are always people — historians, journalists and scientists, for starters — for whom the truth is paramount and essential.

At the very least, “The Meaning of Hitler” is a tribute to a generation of truth-seekers and truth-tellers. Savor their wisdom, and heed their warning.