This chapter defines a quantitative notion of a person’s lifetime wellbeing. It does so on the basis of betterness among uncertain prospects, using expected utility theory (which the chapter explains) and a theorem of John Harsanyi. It adopts the assumption of Daniel Bernoulli that wellbeing is risk-neutral. It gives an account of interpersonal comparisons of wellbeing. Keywords:quantities of wellbeing,
Harsanyi,
Bernoulli,
risk neutrality,
interpersonal comparisons,
expected utility theory