It’s true in the sense that, in aggregate, the risk of being attacked with a knife is tiny.
It’s irrelevant because this risk is so unequally distributed. For a middle-aged woman in Whissendine, the chances of a knife attack are too low to bother with. For a young black man in Willesden, it is otherwise.
There’s an analogy here with macroeconomic data. The fact that the economy is still growing is of no comfort to a man who’s lost his job. People who spend lots on petrol and electricity don’t think official inflation figures are true for them. And they are right. Macro-level data don’t describe individual experience.
Now, if John merely wants to tell people who are trying to stoke up a nationwide moral panic to get a grip, he’s wholly correct.
But the aggregate data don’t refute David Cameron’s claim that we have a “broken society.” What they show - given the correlation between poverty and the risk of a stabbing - is that the break is, as one of Cameron’s predecessors said, between the rich and the poor.
It would be foolish if the left failed to appreciate this.