qualitative identity See IDENTITY. qualitative predicate, a kind of predicate postulated in some attempts to solve the grue paradox. (1) On the syntactic view, a qualitative predicate is a syntactically more or less simple predicate. Such simplicity, however, is relative to the choice of primitives in a language. In English, ‘green’ and ‘blue’ are primitive, while ‘grue’ and ‘bleen’ must be introduced by definitions (‘green and first examined before T, or blue otherwise’, ‘blue and first examined before T, or green otherwise’, respectively). In other languages, ‘grue’ and ‘bleen’ may be primitive and hence ‘simple,’ while ‘green’ and ‘blue’ must be introduced by definitions (‘grue and first examined before T, or bleen otherwise’, ‘bleen and first examined before T, or grue otherwise’, respectively). (2) On the semantic view, a qualitative predicate is a predicate to which there corresponds a property that is ‘natural’ (to us) or of easy semantic access. The quality of greenness is easy and natural; the quality of grueness is strained. (3) On the ontological view, a qualitative predicate is a predicate to which there corresponds a property that is woven into the causal or modal structure of reality in a way that gruesome properties are not. See also GRUE PARADOX, PROPERTY. D.A.J.