Abstract

This chapter considers Geach's claims solely as pertaining to the philosophy of language and philosophical logic, though much of the interest of the concept of relative identity concerns its applicability to other areas: the metaphysical controversy about personal identity and the debate in philosophical theology on the doctrine of the Trinity. It describes Geach's views under six headings: the non‐existence of absolute identity; the sortal relativity of identity; the derelativization thesis; the counting thesis; the thesis of the irreducibility of restricted quantification; and the 'name for an A'/'name of an A' distinction. The sortal relativity thesis depends for its significance on the distinction between sortal terms and non‐sortal terms. An important component of Geach's position is his thesis that for any sortal term 'A' there is a distinction between restricted quantification over As and unrestricted quantification over things that are As.