Have you ever heard of group polarisation? Here's how it works. A small group of you are sitting together watching the televised Prime Ministerial debate. One of you thinks Gordon Brown is doing well and you're not convinced by the other two. Soon you are laughing at every Nick Clegg and David Cameron answer. The one member of the group who hates Brown begins to see his merits. By the end of the evening, you've all gone Browntastic.
Then you see the poll. Much of the rest of the world thinks Clegg won. And there's a group at work who watched and gave the gold medal to Cameron.
In his book Going to Extremes, Cass Sunstein explains what has just happened. When groups get together, they feel out each others' views and then, together, they work themselves into a bit of a lather. The dissidents are embarrassed into silence, those in the majority keep confirming the rightness of each others' position. The group as a whole becomes more extreme.
Sunstein has tested this thesis. He took judges in the United States and divided them into those judging panels with exclusively Democratic appointees and those with exclusively Republican appointees. He showed how their decisions were very different from each other and more extreme than mixed panels.
But we didn't need his test really, now did we? Because group polarisation is all around us. Take, I am sad to say, the Catholic church.
Here, a group of people bound together by a creed that stresses the need to avoid sin, and a desire to promote Godliness, have got themselves into what can only be described as an unholy mess.
First there were the acts themselves, the repeated failure to deal with terrible abuse. Over and over again, when challenged to deal with the most dreadful acts of rape and assault, members of the church hierarchy decided to protect the criminal rather than the victim. They showed compassion to the sinner, but not justice to those sinned against. I have tried hard to find an excuse for this - because I know many Catholics and they are hurt by the criticism of their Church, but all I can find is an explanation.
It is an explanation that fits the second part of the unholy mess, too. And that part is their response to the abuse scandal since it became public.
There is only one possible attitude for an organisation to strike when it is embroiled in a scandal this big. Total contrition. And some leaders have managed this. But not enough of them. Others have blamed the gays. And, wouldn't you just know it, the Jews, too. Still more common has been blaming the media.
Viewed from the outside, this all looks awful and completely self-defeating. But that's the point. These people are viewing it from the inside. And the more they talk to each other, the more wrong they get.
But before we all settle back feeling smug, let me explain why I have told you this. It's because we Jews are as prone to group polarisation as anyone else. Last week, the JC's front page carried a story I could hardly credit. Judge Richard Goldstone has had to agree not to attend his own grandson's barmitzvah to avoid protests against his report on Gaza spoiling the occasion. What a disgrace.
They even had a rabbi saying he thought the judge's withdrawal was "sensible". What's the point of all that learning, rabbi, if you can't make a simple moral judgment correctly?
A group of people - South African Jews across the entire Johannesburg community - have persuaded each other that this is acceptable. What an individual with a conscience can see is wrong, a group cannot see. How sad.