Multiple selves is a conventional assumption in behavioural welfare economics for modelling intrapersonal well-being. Yet an important question is which self has normative authority over others. In this paper, we advance an argument for what we call the ‘ontological approach’ to personal identity in behavioural welfare economics. According to this approach, ethical questions – such as which preference should be granted normative authority over another – can be informed by the ontological criterion of personal persistence, which aims at determining what (...) it takes for an individual to persist from one time to another. (shrink)