  Another approach toward such languages \(L_{T}\) which contain their own truth predicate \(T\) was offered by S. Kripke (1975) and is essentially based upon the idea of considering \(T\) as a partial predicate, i.e. as a predicate which has “truth value gaps”. In a case Kripke (1975) considers, these truth value gaps behave “truth functionally” and so can be treated like a third truth degree. Their propagation in compound sentences then becomes describable by suitable truth degree functions of three-valued systems. In Kripke’s (1975) approach this reference was to three-valued systems which S. C. Kleene (1938) had considered in the (mathematical) context of partial functions and predicates in recursion theory.