Abstract The hierarchy of metainferences ST has garnered significant attention in the literature due to its ability to recover as many classical metainferences as possible. In this study, we introduce a fixed point validity predicate for ST. Subsequently, we demonstrate not only that this predicate captures all valid metainferences according to ST logic but also the naïve principles governing validity. The resulting theory of validity is non-trivial, and it can internalize its valid metainferences.
Barrio et al. (Tue,) studied this question.