CK Stead called the mob hysteria an "embarrassing contagion" but groupthink is possibly more sinister than embarrassing. It is dangerous, partly because moods are highly contagious, now more than ever.
There are trends in expressing emotions. The 1970s let-it-all-hang-out culture encouraged people to vent and share their anger, the theory being that if you keep it squashed inside it festers but if you let it out - free the doves, man! - then it will dissipate and everyone will be happy.
That is no longer current thinking. These days it is recognised that attitudes follow behaviour as well as vice versa. Researchers have found if you make people clamp a pencil between their teeth to simulate a "smile" they will feel more cheerful than if they frown. If you behave as if you feel an emotion then you will start to feel that; if you act angry you will get angrier.
That has led to new trends like mood freezing - the suggestion to shut your negative mood down rather than being cathartic and letting it all out.
Anger is also addictive. With an online environment, and media, that encourages us to vent - everyone is a columnist these days - it could be making us angrier. The wrath might be worthwhile, of course, if it achieves something - stopping rape, for example - but I'm not sure this is the case. And all this toxic anger is not so good if it causes group polarisation, making furious people more furious.
New Zealanders already have something of a one-note emotional palette. Our dour European culture doesn't make it easy to show a repertoire of feelings, especially negative ones. In lieu of being able to show that you feel fear, sadness, guilt and shame, we all just get very cross. Not that we are often aware of this. People often get disconnected from their primary emotions by diluting them and giving them another name.
For example, instead of saying they're afraid, which is wussy, many people will say they feel anxious or worried, which is much more acceptable. Instead of saying they feel sad (or even knowing they are sad) many people will say they feel tired or sick. If we find it so alluring to be angry, maybe we should look at whether it is really anger we are feeling or perhaps something else?
Psychoanalyst Stephen Grosz in his bestselling book, The Examined Life, talks about "the bigger the front, the bigger the back" as a way of describing how we unconsciously put aspects of ourselves we find shameful on to another person or group.
Like Grosz, I am curious when I see so much self-righteousness - or "front" - on display. It is good that we can see a monstrous act, such as rape, and identify it as monstrous. But some monsters, such as the glamorous thrill of righteous anger, might be better off being shut away before they can do more damage.
Or as a columnist might say, just leave it to the professionals.