ABSTRACT
As with so many terms in philosophy, the exact definition of ‘sortal’ is philosophically contentious. It is uncontroversial that sortals (i) are a kind of linguistic term (or perhaps a kind of concept), and (ii) take numerical modifiers, that is, can be associated with numerical adjectives. The word ‘cat’ is a sortal: it is a linguistic term that takes numerical modifiers, that is, we can say, ‘two cats’, ‘three cats’, etc. Outside philosophy, terms which take numerical modifiers are called ‘count nouns’ and are contrasted with ‘mass nouns’ such as ‘milk’, which do not take numerical modifiers – you cannot say ‘two milks’. (You can, however, say ‘two beers’: ‘beer’ sometimes acts as a mass noun and sometimes as a count noun.)
However, being a count noun is sometimes taken to be necessary, but not sufficient, for being a sortal. Sortals are sometimes understood to be count nouns (or concepts expressed by count nouns) that ‘sort’ things into kinds in some metaphysically significant sense, perhaps by specifying the essence of things of that kind. Sometimes philosophers distinguish sortals which group things into kinds, known as ‘pure sortals’ or ‘substance sortals’ – ‘cat’ or ‘electron’ – from ‘phase sortals’, which denote a certain phase of a thing’s existence – ‘kitten’ or ‘child’ – or from ‘restricted sortals’, which denote certain kind of substance with a certain kind of property – ‘white kitten’, ‘green car’.
