Abstract
This chapter contains sections titled: This chapter generalizes the technique to other cases, including the identity of species and persons, and makes the appropriate concept of approximation precise. What need to be found are generalizations with worthwhile instances, beyond those already considered. The first section abstracts a formal schema: when a supposed criterion of identity M for objects of some kind turns out to be non‐transitive, the best approximation to the original criterion is a maximal M‐relation. The second section applies the schema to operationally defined quantities, species, and non‐Cantorian cardinal numbers. The third section applies it in more detail to persons. The fourth section considers the case in which M is held to be a sufficient condition rather than a necessary one. The final section analyses the relevant concept of a best approximation.