Sir Ray Avery, an inspiring foe of all varieties of bullying, tells a story that illustrates the bystander effect perfectly. It's about a cartoon from World War II that shows one person saying to another: "You know, when Hitler invaded Poland, I nearly said something."
The bystander effect has been in the news thanks to a particularly spectacular example of it in the case of Charles Saatchi's assault on Nigella Lawson, in which one witness managed to sound like they were the victim: "It was utterly shocking to watch .. it was horrific, really." Poor pet. Must have been ghastly.
The Saatchi assault was yet another violent incident on a spectrum that ranges from "lovingly" hitting a child for discipline to a death such as that of schoolboy Stephen Dudley.
There is a sense in which Dudley was also a victim of bystander effect. The after-school scrap to settle some pissant difference has been around a long time.
It is, of course, a watered-down version of yesteryear's duels of honour. These events always take place in front of an audience.
Every person who stands by and watches this take place shares some of the blame.
I hope the parents of the young bystanders who watched Dudley receive the blows that killed him have made this clear to their offspring.
Violence is particularly prevalent in entertainment aimed at young men. Violence in entertainment is, of course, as old as entertainment. Ancient Greek drama is awash with blood, and there's plenty of it in Shakespeare, though it's not the kind you'd want to emulate.
But video game and contemporary movie violence is graphic, sadistic, glossy and alluring. Although violence in media doesn't cause violence - frustration, low self-esteem and an inability to express oneself cause violence - it creates a climate of cool around it.
Boxing continues to attract celebrities and the wealthy with charity bouts, and big-name fighters are lauded. It's no wonder young people think hitting each other is acceptable.
We've seen a procession of sports and media figures clogging the courts in recent years as a consequence of violent incidents that occurred around the house or out on the town.
Although the root causes of violence are hard to address, there is one remedy that will have an impact, won't require a commission of inquiry and costs next to nothing. We've already seen it work with some drugs.
This country had a lot of heroin users at the end of the 1970s. The reason people stopped using that drug had nothing to do with the supply or the price. It had everything to do with the fact that heroin became uncool. It was seen as a loser's drug.
On anecdotal evidence, it seems something similar has happened with P. There were just too many stories about people on P behaving like loons - and not funny, put-your-pants-back-on loons; tedious, please-go-away-you're-annoying loons. And smoking hasn't been cool for so long that it's about to disappear altogether without further assistance.
We'll never eradicate violence between individuals. We're hard-wired for it, but we're hard-wired for lots of base behaviours we manage to control. Once violence is seen as uncool, as the last resort of pinheads who have to use fists to solve problems because their brains aren't up to it, then the amount of violence in society is guaranteed to diminish.
Kim Kardashian and Kanye West have reportedly named their daughter North West. That's a relief. I had been worried the wee mite might be burdened with one of those ridiculous celebrity baby names.