Full Idea
'Projectible' predicates are predicates F and G whose shared instances all do count, for whatever reason, towards confirmation of 'All F are G'. ….A projectible predicate is one that is true of all and only the things of a kind.
Gist of Idea
Projectible predicates can be universalised about the kind to which they refer
Source
Willard Quine (Natural Kinds [1969], p.115-6)
Book Reference
Quine,Willard: 'Ontological Relativity and Other Essays' [Columbia 1969], p.115
A Reaction
Both Quine and Goodman are infuriatingly brief about the introduction of this concept. 'Red' is true of all ripe tomatoes, but not 'only' of them. Hardly any predicates are true only of one kind. Is that a scholastic 'proprium'?