Patients suffering from “lifestyle” conditions are most often viewed as responsible for their illness, and so not considered to be a priority for healthcare resources. Instead, their treatment is financed on instrumental grounds: it is better to treat the condition now than to incur higher costs later of not doing so. An alternative register of justification at work in public healthcare policies is not motivated by instrumental considerations. Instead, it seeks to articulate an ethical case for prioritizing lifestyle conditions. Within this framework, we draw on the notion of vital need within the tradition of humanistic philosophy to argue that solidarity justifies the treatment of such conditions, exemplified here by obesity. We use the theoretical framework of economics of convention to present these two registers of justification at work in public healthcare policies. The importance of humanistic criticism prevents instrumental logic from being completely dominant.