This one is really amazing given the current hysteria concerning accusations of sexual harassment from long ago:
Take the news in Alabama this week - it's a textbook case. An older guy in a powerful position is accused by women of molesting them when they were teenagers. One of the women says she was only 14.
Roy Moore is now 70 years old and running to be the next US senator for the state of Alabama. Some polls suggest he could win.
There is also a report in the New Yorker magazine that Mr Moore was banned from visiting a local shopping mall because of his tendency to badger teenage girls there. It takes quite a bit to be banned from a shopping mall....
....several state Republican officials and local Republican party committees have come to Judge Moore's defence.
Ed Henry, a Republican state representative, suggested it's the women who accused Mr Moore who should be prosecuted, for not coming forward with their stories sooner and so allowing an accused predator to roam free. Seriously.
And Jerry Pow, the Republican chairman of Bibb County, Alabama, told a reporter he'd vote for Roy Moore even if the allegations are true, and he did commit a sex crime against a teenager.
Take a breath and let that sink in for a moment - it's 2017 and an Alabama Republican official says he'd vote for a paedophile.
What's so revealing in the context of tribalism is Mr Pow's reasoning. He'd vote for Moore, he says, because he can't bring himself to vote for the Democrat in the race.
Jerry Pow believes any Democrat is de facto worse than any Republican - even if that Republican molested girls and then lied about it.
This is a whole step beyond the realm of fake news. This is taking facts, chucking them out with the trash and quite happily forming your own opinions based on nothing more flimsy than pure prejudice.
To the extent that tribalism comes from the top, it's worth noting President Trump has been conspicuously quiet on the subject of Republican Roy Moore, but tweeted scathing comments about Democrat Al Franken.
The Republican Governor of Alabama has added her voice to those saying she believes the women but will vote for Mr Moore nonetheless, to get another Republican in the Senate.
And here's the kicker. According to researchers, we are all prone to doing just that. You, me, our friends, our kids, our news editors, and yes, the good people of Alabama.