(Melina Mara/The Washington Post)

As you may have heard, speaking to an audience in New Hampshire, Joe Biden told a very moving story about his interaction with a war hero. The only problem is that he got just about every detail in the story wrong, as a Post investigation subsequently revealed.

Now Biden has pushed back — mainly by arguing that there’s no problem with what he did, because he got one key fact about the story, and the spirit of it, correct. This is not a good response.

As The Post article details, Biden’s story did have something in common with one episode in 2011, where Biden did pin a medal on a soldier who was emotionally crushed and didn’t think he deserved it.

But that soldier and that episode match none of the other details in the story as Biden told it. The other details conform to an entirely different episode, and Biden never pinned a medal on the person at the center of it.

Former vice president Joe Biden has frequently jumbled the details of a dramatic story from one of his many visits to U.S. soldiers in Afghanistan. (Video: The Washington Post)

Biden brushed off this whole affair in an interview with my Post colleague Jonathan Capehart.

In the interview, Biden seemed to confirm that he was talking about the 2011 episode, then said: “Turns out that’s true … that’s what I was talking about.” Biden then allowed that there was another separate incident but didn’t even allow that he had conflated facts from that incident with this one.

“I was making the point how courageous these people are,” Biden said, adding: "I don’t know what the problem is. What is it that I said wrong?”

Pressed by Capehart on the fact that there were separate incidents that Biden conflated, he said: “He just confirmed it happened.”

In other words, Biden is saying that because a key element of the story he told was true of another episode — and because that supported his intended meaning and the larger story he was trying to tell — this means getting all these other basic facts wrong, or conflating two episodes in a misleading way, isn’t a serious issue.

What’s troubling is Biden genuinely doesn’t seem to see a problem here. He treated this as similar to another recent incident where something he said was unfairly taken out of context, as if there was no error whatsoever on his part.

But Biden didn’t have to respond this way. Biden could have easily conceded that he should have gotten his facts right, while also saying what he did say, which is that his larger intended point was undiminished and important.

Better yet, Biden could respond to this affair by saying, “Let me take the opportunity to tell the story accurately, because this is important,” then tell the correct version, and then reiterate that these stories underscore his reverence for the bravery and sacrifice of these young men.

To be clear, my point here isn’t necessarily that Biden’s shaky grasp of the details raises concerns about his age or mental fitness for a grueling campaign, though such concerns are understandable.

Nor is there anything even remotely equivalent between unintentionally getting things wrong this way and doing what Trump does — engage in relentless disinformation for the express purpose of spreading confusion and undermining the very possibility of shared truth and deliberative argument. Biden’s general intentions toward the truth are incalculably better than Trump’s are, and that matters greatly.

But the Democratic nominee against Trump simply cannot treat facts as if they are expendable in this fashion — no matter how well-intentioned he is.

Trump is going to run the most dishonest, propaganda-driven, disinformation-saturated campaign in memory, or perhaps ever in U.S. history. Prosecuting the case against Trump’s nonstop lying and contempt for the truth and reasoned discourse is going to be a key part of making the case against his profound unfitness for the presidency.

Cavalier treatment of facts will muddle this case. Yes, this will be partly because some in the media will draw an equivalence between this kind of slipshod treatment of facts on the one hand and Trumpian disinformation on the other. Yes, that will be ridiculous and unfair. But it will be a factor, and the Democratic nominee cannot give this media instinct something to feed on.

The eventual nominee must leave no doubt about his or her commitment to factual accuracy, because it will help sharpen the contrast with Trump’s unfitness — it will tell voters that the nominee is offering a sharp break with the pathologies of the Trump era. And obviously it’s a worthwhile value in its own right.

Indeed, as progressive strategist Mike Lux pointed out, the other leading Democrats are less likely to stray in this way. “Elizabeth Warren is not going to get her facts wrong very often,” Lux said. “Kamala Harris, the prosecutor, is not going to get her facts wrong very often.”

I don’t have any idea whether Democratic voters will end up caring about this contrast. But Biden himself should. At the very least, one hopes Biden is privately taking from this episode the lesson that it’s important to avoid these kinds of errors in the future, not that nothing whatsoever was wrong here.

Maybe Democratic voters won’t end up holding this tendency against Biden at all. But if Biden’s only response to this is to count on that happening, that’s not good enough, either.

Read more:

Jonathan Capehart: Biden’s dueling narratives: One good, one not so much

Transcript: Jonathan Capehart interviews Joe Biden

Dana Milbank: Joe Biden isn’t just a gaffe machine. He’s the Lamborghini of gaffes.

Jennifer Rubin: The staying power of Joe Biden