The question of whether we are responsible for the harm we cause goes to the heart of who we think we are, and how we believe society should run. Guilt, blame, the existence of evil, and free will itself can complicate this question to the point of near absurdity. And yet, as absurd as it may be, it is unavoidable. Taking a binary approach, whichever path one chooses, can lead to difficulties very quickly. On the one hand, if we are solely responsible for the things we do wrong, some genuinely malevolent parties get off scot-free. On the other, if we locate responsibility entirely outside the individual, we relegate ourselves to sentient flotsam buffeted by currents beyond our control. In my own medical career, I have seen attitudes shift considerably around the idea that individuals should take personal responsibility for the harm they do to themselves. Self-injurious behaviours such as alcoholism and drug addiction have rightly been reframed as diseases rather than lifestyle choices. In the case of opiate dependence, as the huge numbers of people hooked on prescription painkillers in the United States demonstrates, “bad” behaviour is often caused directly by doctors and pharmaceutical companies. But even with less dramatic examples, there is a growing acknowledgement that personal choice is not the biggest driving factor. While we all inherit a deck of cards shuffled at conception in terms of our genetic predispositions to illness or certain behaviours, it is context that can either engage the safety catch or pull the trigger. Social determinants of health, including income, physical environment, working conditions, housing and access to good food and healthcare account for up to 55% of health outcomes. They are the source of staggering disparities in life expectancy between the most and least deprived places. A child born in Singapore can expect 30 years more life than a child born in Chad. In the UK, men in Richmond upon Thames have a healthy life expectancy of 71.4 years, compared to 58.4 years for their counterparts in Barking and Dagenham. Over years of working as an inner city GP, I have met people whose daily habits and apparent choices seemed inexorably to be pushing them towards an early grave. One person would eat a single vast meal comprising huge amounts of junk food washed down with litres of fizzy drink, exacerbating a number of medical conditions. Thinking about the forces that conspired to create this lifestyle helped me move beyond the unhelpful, frustrating view that this was simply a lone individual screwing up. In the context of stressful working conditions, being depressed, living in inadequate housing, and knowing how to access cheap, familiar and tasty food that’s ready to eat, it made sense for that person to do what they did. Getting from one poorly paid shift to the next left little time, resources or energy to change direction. The late Paul Farmer, a medical anthropologist, physician and leading figure in global health education, was instrumental in bringing the concept of structural violence to a wider audience. His teaching changed my medical practice profoundly. Farmer’s powerful ethnographic vignettes from Haiti illustrated with heartbreaking power how poverty, political and social arrangements constrained people’s life choices, forming a silent web of violence that made contracting HIV through unprotected sex seem almost inevitable for some vulnerable young people. It is easier to understand the contexts that shape self-injury than it is to comprehend acts of harm committed against others. Victims of robbery or assault want justice, not a sob story about how their burglar ended up on the wrong side of the law. But evidence shows that, like disease, crime has a recipe: social, economic and environmental disadvantage. Indeed, risk factor research in criminology has its origins in public health. Large family size, unstable income, family members involved in crime, and easy access to drugs and firearms are all associated with a greater risk of falling into criminality. Studies in several countries have shown very strong associations between the levels of lead in the blood of pre-school children and subsequent levels of crime in the area. More than 40% of adult prisoners had an abusive childhood, and a disproportionate number were in care as children. But risk factors and social determinants of life outcomes need to be handled with care. They are not by themselves predictors of a person’s future. Everyone has heard of the archetypal granny who lived to 100 despite smoking 60 a day, and her not-so-fortunate opposite. There are no crystal balls, but on a population level, understanding the contexts and causes of harmful behaviour can be transformative – and the thread that ties most of these causes together is poverty. In London, the poorest 10% of areas have rates of violence, robbery and sexual offences 2.6 times higher than the richest 10%. When asked what he would spend £5bn on, former chief constable of Merseyside police Andy Cooke said he would spend 20% on law enforcement, and 80% on tackling the root causes of poverty and inequality. Yet, understanding context alone is no guarantee of progressive social policy. In relation to crime, both perspectives – that the fault lies with the individual, or that it lies with society – have been used to conclude that locking people up is the right solution. Policy is not just based on evidence: the heady brew of public opinion, political ideology and notions of morality can induce astonishingly self-destructive approaches. Since 2000, the number of people in prison worldwide has increased by 24% to 11.5 million. The US has seen a 500% increase in the last 40 years. Increasing sentence severity has no impact on crime rates, and incarceration almost always inflames the root causes of crime, often leaving people and their families much worse off when they get out. The flipside of acknowledging how crucial the factors outside our control are in shaping our worst choices is that we are obliged to have a little scepticism about our good deeds as well. Are our acts of self-control and generosity really down to nobility of character, or has our lot in life simply presented fewer obstacles to living well? Remarkably, research on young Americans from poor communities at high risk of criminal activity but who managed, with great determination, to avoid prison and stay in school, showed that they had signs of accelerated biological ageing. It takes huge effort to change habits and to steer a life’s ship away from the path of least resistance. While on a population level, understanding the causes of bad choices is necessary – but not sufficient – to inform good policy, on an individual level it is perhaps better to avoid bringing it into the conversation. Social labelling can be tremendously powerful, and toxic. It does not help people like my junk food fan to view themselves as victims. The opposite is true. Human dignity and hope require faith in free will, even if agency is at worst an illusion, and at best a partial explanation wreathed in caveats. Further reading Pathologies of Power: Health, Human Rights, and the New War on the Poor by Paul Farmer (University of California, £24) Empire of Pain: The Secret History of the Sackler Dynasty by Patrick Radden Keefe (Picador, £9.99) Tiny Habits: Why Starting Small Makes Lasting Change Easy by BJ Fogg (Virgin, £10.99)