It’s one thing to be held accountable for things you actually did.

But when Lawrence O’Donnell of MSNBC interviewed Herman Cain, counterfactuals ruled the day.

I’d hate for all parental candidates to be held to Lawrence O’ Donnell’s standards.

In Herman Cain’s book, he describes — in somewhat rambling prose — the challenges of growing up during segregation. “Stay out of trouble,” Cain remembered his father saying. “And we did.”

“Where do you think black people would be sitting on the bus today if Rosa Parks had followed your father’s advice?” O’Donnell asked, in only one of a long series of provocative and totally unilluminating questions.

O’Donnell then badgered Cain for “sitting on the sidelines” during the civil rights movement.

There are many questions that you could pose to Herman Cain. “What on earth is the 9-9-9 plan?” “Has anyone ever actually eaten at a Godfather’s Pizza?” There are even good questions.

When this photo was taken, you should have been resolving the Middle Eastern conflict! (Spencer Platt/GETTY IMAGES)

None of the ideas that O’Donnell had were bad — participate in the civil rights movement. Fight in the Vietnam War. Never mind that Cain was already serving his country in a civilian capacity. Never mind that he was still a student at the height of the movement. Do we really want to go down this path? Suppose he had managed to do both. “Why did you also not seek a cure for cancer?” I picture O’Donnell asking. “Thousands perished because of your failure to find a cure.”

“You didn’t know, Lawrence, what I was doing . . . maybe, just maybe, I had a sick relative!” Cain would have answered, as he did this time. Possibly not the strongest rebuttal, but still.

Surely what Cain actually did is sufficient fodder for questions.

But no. Where do you go from here? “Why didn’t you prevent the Cuban missile crisis?” O’Donnell will bellow at Rick Perry. “I was 12,” Perry will say, as sheepishly as he can manage.

“Not good enough!”

Next, O’Donnell will be badgering Mitt Romney for sitting on the sidelines during the War of 1812. “Why weren’t you signing the Declaration of Independence?” he will angrily demand. “Where would America be if the Founders had been like you?”

It’s one thing to ask hardball questions. But it’s another to engage in counterfactual baiting.

I’m sure Lawrence O’Donnell began marching and protesting and signing up for drafts from within the womb. But some of us walked different paths. I just hope he asks the same questions of the other candidates and holds everyone to the same standard. “Why did you just sit there and let Rome fall? Why didn’t you prevent the assassination of JFK?” When O’Donnell was 7, he had already averted Ragnarok six times.

Things done and things left undone.

Someday, we may be held accountable for those, but by Lawrence O’Donnell?

The only thing Cain should have done differently was not accept that interview request.