PHILOSOPHERS have often distinguished two kinds of truth: the truth of some statements is logical, necessary, based upon meaning, while that of other statements is empirical, contingent, dependent upon the facts of the world. The following two statements belong to the first kind: (1) 'Fido is black or Fido is not black' (2) 'If Jack is a bachelor, then he is not married' In either case it is sufficient to understand the statement in order to establish its truth; knowledge of (extra-linguistic) facts is not involved. However, there is a difference. To ascertain the truth of (1), only the meanings of the logical particles ('is,' 'or,' 'not') are required; the meanings of the descriptive (i.e., nonlogical) words ('Fido,' 'black') are irrelevant (except that they must belong to suitable types). For (2), on the other hand, the meanings of some descriptive words are involved, viz., those of 'bachelor' and 'married.'
Carnap, R., Meaning Postulates, Philos Stud (1952) 3: 65 - 73 -- pag. 65.