One of the best-known ideas about how our surroundings shape crime is the ‘broken windows’ theory. Proposed by James Wilson and George Kelling in 1982, the idea was that small amounts of disorder – like broken windows – could spread and grow into more severe crimes. The solution, therefore, was to restore and maintain public order. The broken windows theory would become popular among police forces, most notably in New York City during the 1990s, where it inspired a heavy crackdown on minor crimes like subway fare dodging. These measures coincided with the massive drop in crime in the city, leading to claims that arrests for misdemeanours had stopped the larger offences.[89]
Not everyone was comfortable with the way that the broken windows theory was adopted. One of them was Kelling himself. He has pointed out that the original notion of broken windows was about social order rather than arrests. But the definition of public disorder can be a matter of perspective. Are those people loitering or waiting for a friend? Is that wall covered in graffiti or street art? Kelling suggested that it’s not as simple as just telling police officers to restore order in an area. ‘Any officer who really wants to do order maintenance has to be able to answer satisfactorily the question, “Why do you decide to arrest one person who’s urinating in public and not arrest another?”’ he said in 2016. ‘If you can’t answer that question, if you just say “Well, it’s common sense,” you get very, very worried.’[90]
What’s more, it’s not clear that aggressively punishing minor offences was the main reason for New York’s decline in crime in the 90s. There’s little evidence that New York’s reduction was a direct result of broken windows policing. Many other US cities saw a drop in crime during that period, despite using different policing strategies. Of course, this doesn’t mean broken windows policing has no effect. There’s evidence that the presence of things like graffiti and stray shopping trolleys can make people far more likely to litter or use an out-of-bounds thoroughfare.[91] This suggests that minor disorder will spark other minor offences. The effect seems to work the other way too: attempts to restore order – like picking up litter – can prompt others to tidy up as well.[92] But it’s quite a leap to go from such results to the conclusion that arrests for misdemeanours can explain a massive drop in violence.
So what caused the decline? Economist Steven Levitt has argued that expanded access to abortion after 1973 played a role. His theory goes that this meant there were fewer unwanted children, who would have been more likely to be involved in crime when they grew up. Others blame childhood exposure to leaded petrol and lead paint in the mid-twentieth century, which caused behavioural problems later on; when the level of exposure declined, so did crime. In fact, a recent review found that, in total, academics have proposed twenty-four different explanations for the decline in US crime during the 1990s.[93] These theories have attracted plenty of attention – as well as criticism – but the researchers involved all acknowledge that it’s a complicated question. In reality, the drop in crime was likely the result of a combination of factors.[94]
This is a common problem with outbreaks that occur on long timescales. If we intervene in some way, we might have to wait a long time to see if it has an effect. In the meantime, there might be lots of other changes going on too, making it hard to measure exactly how well our intervention works. Similarly, it can be easier to focus on the immediate effects of a violent event, rather than investigate longer-term harm. Charlotte Watts has pointed out that domestic violence can be transmitted across generations, with affected children becoming involved in violence as adults. However, these children can often be forgotten when discussing interventions. ‘We need to think about support for children growing up in households where there is domestic violence,’ she said.
Historically, it’s been difficult to analyse intergenerational transmission given the timescales involved.[95] This is where public health methods can help, suggests epidemiologist Melissa Tracy, because researchers have experience analysing long-term conditions. ‘That’s the strength of epidemiology, bringing that life course perspective.’
Using public health approaches to prevent crime would be hugely cost-effective, both in the US and elsewhere. Adding together the social, economic and judicial consequences of the average US murder, one study put the cost of a single killing at over $10m.[96] The problem is that the most effective solutions may not be those that people are most comfortable with. Do we want to feel like we’re punishing bad people, or do we want less crime? ‘When it comes to behavior change, threats and punishment are just not that effective,’ said Charlie Ransford of Cure Violence. Although punishment might have some impact, Ransford suggests that other approaches generally work better. ‘What is ultimately most effective at changing a person’s behavior is when you try to sit down and try to listen to them and hear them out, let them air their grievances and really try to understand them,’ he said. ‘And then try to guide them to a healthier way of behaving.’
Projects like Cure Violence have historically focused on in-person interactions, but online social contacts are increasingly influencing the spread of violence as well. ‘The environment has changed,’ Ransford said. ‘You need to make an adjustment. Now we’re hiring workers who specialise in combing through social media to look for conflicts that need to
