There are only two possible explanations for that photo.

One is intentional malice. That is the explanation favored by Rabbi Marvin Hier of the Simon Wiesenthal Center in Los Angeles. That picture, he told The Associated Press, is “beyond the pale.”

The second explanation is ignorance, i.e., that when a troupe of United States Marines posed in Afghanistan with a flag bearing the logo — a double “s” in the shape of lighting bolts — of the Schutzstaffel, or SS, the military and police arm of the Nazi party, they had no idea what it was. Indeed, a spokeswoman at Camp Pendleton in California where the Marines are based, says the men in the photo, which surfaced on the website of a Florida weapons company, thought the double “s” stood for “sniper scouts.” The spokeswoman says the Marines were unaware the flag symbolized the thugs and bully boys who, under Adolf Hitler’s command, burned down much of Jewish Europe during the Holocaust.

While Rabbi Hier may be right that this photo represents a knowing act of anti-Semitism, it seems more likely the second explanation is true and that what it actually represents is the fact most Americans don’t know their past from a hole in the ground. This is a perception quantified by research, including a 2000 study, which found that most seniors at America’s top colleges — our best and brightest — could not answer basic questions about American history. The reason? In many schools, history is no longer a required course.

So for the second time in as many months, the Marines find themselves embroiled in controversy over embarrassing imagery. The first, of course, was that video of Marines urinating on the corpses of dead Taliban. It spoke to the dehumanizing nature of war.

This new image, however, speaks to the degradation of American memory.

As many as 60 million people worldwide died in the war to rid the world of that flag and all it represents. Over 400,000 of them were Americans. It is a pungent obscenity to see men who wear the same uniform and salute the same colors posing before a flag symbolizing those who slaughtered their countrymen.

In a sense, it would be easier if those Marines were indeed motivated by hatred because that, at least, you can get your arms around. You know what to do with it: cull the ranks, require sensitivity training, increase vigilance against extremism.

But what do we do if the culprit is simply the ignorance of the undereducated? That, after all, is larger than the Marines, indicts not just a few men posing in a hostile place far from home, but also the nation that sent them there. It indicts the facts-optional “truthiness” that often informs — that word is used advisedly — political debate. And it indicts the short-sightedness that led us to believe we could diminish our own history and pay no price for doing so.

Now the price stares out at us: American Marines posing with a Nazi flag.

In the photo they look young, these Marines, part of that coming generation that will write the next chapter of the American story. That should give us pause. That should worry us some. To truly comprehend tomorrow, you must first comprehend yesterday.

So how can you write the next chapter of a story you don’t even know?