A person’s geographic, social and economic circumstances affect their health and life expectancy. These factors are referred to as social determinants and are difficult for individuals to change. Many social determinants of health can be addressed only through collective action, such as by governments. This chapter looks at another influence on public health: the choices each of us makes. The choices people make will influence their health and the health of others. Public health interventions such as campaigns asking people to eat better, exercise more, quit smoking and take care on the roads assume that people will modify their behaviour in response to warnings and advice. This assumption is questionable. People routinely ignore health messages. To change people’s behaviour we need to understand how and why people make good and bad choices. That is why models of individual behaviour choice are described in this chapter. The chapter also considers whether people are truly free to make their own choices, or whether individual decisions are at least partly determined socially.

Legal duties are derived by decisions that people have made, when obligations are fairly implied by those decisions.