There’s a troubling trend in America — if there’s someone you disagree with, shout them down.

The latest example came the other night at a public event where Robert Cherny, a San Francisco State history professor emeritus, was talking about the Victor Arnautoff’s Depression-era mural at Washington High School in San Francisco — the one the school board wants to destroy because it depicts a dead Indian and black slaves.

Two hundred people packed into the ILWU Local 34 hall to hear what Cherny had to say about Arnautoff and the mural’s origins — and there’s no greater authority. Cherny literally wrote the book on the artist.

But for 20 minutes, they had to listen instead to four people who took over the meeting to harangue them about how upset they are about the mural. Chants of “Shame! Shame!” from people who came to hear Cherny had no effect.

The people who took over the meeting say they’re traumatized by the mural. They’ve clearly been traumatized by something. They’d be horrified by the comparison, but they’re really no different from the most boorish of President Trump’s supporters. Any disruption is justified to these folks to make a point.

As for that mural: I’m the father of a Washington High graduate. My daughter was never traumatized by Arnautoff’s painting — as a matter of fact, it generated conversations at home that otherwise would not have occurred. It was a learning experience for her, and for me.

I was having a different sort of conversation at lunch the other day when the question was posed: Can school board members be recalled?

The answer is yes.

The odd squad: All the talk about dissension among House Democrats is a bit overblown.

There are 235 Democrats in the House. Speaker Nancy Pelosi has only four really rebellious members, “the squad” led by hero-of-the-left Alexandria Ocasio-Cortez of New York.

When I was Assembly speaker I had five rebels on my hands, and they actually organized to try to get rid of me. They didn’t succeed, because when you come right down to it, five people out of 50 ain’t a majority.

I’m sure Pelosi’s four rebels will find that out soon enough.

Bigger things: San Francisco Supervisor Shamann Walton is certainly on the move.

Since taking office in January, the supervisor for Bayview-Hunters Point has led the fight to ban the sale of vaping smokes in the city, been a leader in the battle to shut down juvenile hall and, most recently, was the only non-Asian American politician to attend the swearing-in of the newest board member of the Chinese Chamber of Commerce.

The last time I looked, Chinatown was a good distance from the Bayview. But then, Walton may have bigger plans than just representing the southeast side of the city.

Big Apple report: Next time you’re in New York, I highly recommend a visit to Hudson Yards, the gigantic development on the West Side — and in particular the new Thomas Keller restaurant, the TAK Room.

It’s a throwback to the Cotton Club in Harlem. The music sounds just as good as it did in the ’40s and the ’50s, and the food is first-rate. It’s in a square-block mall that’s Union Square, Rodeo Drive and Madison Avenue wrapped into one.

By land and sea: My item a couple of weeks back about former Rep. Phil Burton’s famous skill at gerrymandering prompted a call from former California Secretary of State Kevin Shelley to remind me of the district that Phil drew for his brother, John Burton.

Believe it or not, the district included parts of San Francisco, Marin County and Vallejo.

The joke was that it took three bridges and a ferry to cover the area.

Someone pointed out to Phil that as a rule, whenever possible, congressional districts should be connected by land.

To which Phil replied: “And it is — at low tide.”

Want to sound off? Email: wbrown@sfchronicle.com