Pinker’s way of thinking encourages a focus on the context, the place where people live, the schools they go to, the offices in which they work. Individual risks are still important but his work encourages the tending of the space around the individual. Here are some examples of the idea in action.

One of our current projects is called Street to Scale. We give money directly to citizens, young people included, to do good things in their community. When we started, a high proportion of the money either went unspent, or was misspent. ‘Who are you?’, the young people would ask, ‘Why should we trust you?’

We put a lot of effort into brand, in making sure the kit used to deliver Street to Scale looked bona fide, serious. We started using WhatsApp to build trusting relationships with the people managing and spending the money. We changed the structure so that a trust relationship developed between citizens who led the work, those that did the work, and the community members who benefited. As trust grew, as people began to say, ‘Ah yes, Street to Scale, this is serious’, so the amount of ethical spend rose. Unethical spend is now below five per cent. (And, trust, connection and belonging, the reason we do this work, is up).

I mentioned Amelia, my doctoral student. Her thesis was examined by Christina Salmivalli. Like Amelia, Christina was interested in how bystanders reduce bullying. She developed a programme, KIVA, a series of lessons and games that give students conflict resolutions skills and permission to intervene. After testing across Finland, KIVA has been taken up in schools around the world, another contribution to the reduction in violence.

And coming back to Tony Earls. He and his wife Maya Carlson used the finding about the power of collective efficacy in several ways, in several countries. In Tanzania, they trained young people in how to build collective efficacy, a sense of trust and responsibility in each other, and in their community. The young people also learned about HIV prevention. Then they went out onto their local streets and talked to citizens, nurturing trust, and building knowledge about condom use. The net result from a trial across the country was a reduction in HIV transmission.

I have tried several times to get funders and systems interested in this work as a mechanism to reduce knife crime. But it just doesn’t capture the imagination. Everybody wants to focus on the knife carriers. All the evidence reviewed here is telling us to tend the space around the knife carriers.