Sometimes, otherwise smart people will buy into the unbelievable hook, line, and sinker.
Bill Cosby's trial is ongoing, and he's run pretty short on people who still believe him -- but some folks are sticking with him, for some reason.
We've already mentioned that both Bill Cosby's real wife and TV wife support him.
Keshia Knight Pulliam, who played his daughter on The Cosby Show, is also at the trial.
It looks like, defying all reason, she's there to stand by his side every step of the way.
"I came to support because this is where you hear the facts. This is where the truth happens," she told reporters.
It sounds like she's imagining that he's going to be vindicated in this trial.
"Ultimately, it’s easy to support someone and to be in their corner when things are great," she says.
She's right about that one, very specific thing.
"But true family, friendship, integrity," she continues. "Is how people show up and support when things aren’t looking so great, when they aren’t shining."
Usually this means coming over to help a friend move after a breakup, or letting someone crash on your couch after they lost their job, or just hanging out with them when they're not at their best.
That's usually what it means to not be a "fair weather friend."
Somebody needs to tell Keshia Pulliam Knight that rape trials aren't "friendships tests," they're literal trials for sexual assault.
It could be your blood sibling on trial and you would still be completely clear to cut ties with them. Nobody would think that you were only close because their life was going well.
Of course, the reality is that, regardless of what anyone believes, acquittal is totally possible. We all know that.
If you believe in Cosby's innocence, of course you believe that acquittal is possible.
If you believe in Cosby's guilt, you can't help but think of George Zimmerman, of O.J. Simpson, and Casey Anthony -- all of whom were acquitted.
Because the jury system's so, so great, right?
There's something cautious about Keshia's phrasing, though. Anybody else notice that?
With her "this is where the truth happens" line, maybe she's wording her statements so that, no matter how the trial goes, she can still be "right" either way.
If he's acquitted, she can point to her statements and say that she always knew that he was innocent, and that the truth has come out.
Never mind that acquittal of one assault would still leave more than 50 accusations, and that legal and factual innocence do not always overlap.
But, with her careful words, she can still be "right" even if he's convicted.
The jury can hand down a guilty verdict and Keshia could, if she chose, argue that this trial has revealed how powerful this "conspiracy" against Bill Cosby is -- powerful enough to convict a man she believes is innocent.
We don't know if she'll actually go that route. Maybe she doesn't even know.
No matter how the trial turns out or how she responds, we hate to see her do this to herself.