This paper develops a new proof method for two propositional paraconsistent logics: the propositional part of Batens' weak paraconsistent logic CLuN and Schütte's maximally paraconsistent logic Φv. Proofs are de.ned as certain sequences of questions. The method is grounded in Inferential Erotetic Logic.

In this paper I generalize the new approach to nonmonotonicreasoning that was presented in [6]. This generalization results in the inconsistency-adaptive logic PRL . I give proof theory, semantics, mention interesting properties,and comment on the reconstruction and amelioration of other nonmonotoniclogics and mechanisms.

The paper presents a new, intuitive formal language, L E , that fits in with a world view in which experiences are central entities. It is shown how classical logic and an "objective making" adaptive logic can be applied to formulas of L E . The latter logic sheds an interesting light on the creation of theories about "the objective world". The paper also contains a small comment on sentences that are not translatable in L E . In the last (...) section, I revise self-referring sentences by means of their translations in L E. (shrink)

Proof theory and semantics of an adaptive logic that deals adequately with change in individuals with or without a name are presented. New logical constants are introduced, viz. indicators. Within a given context they function as names, predicates and quantifiers at the same time. The thus extended language (of classical logic) has a big expressive power and solvespartly — the (classical) non-logical presuppositions with respect to ‘the existence of individuals’. Nevertheless, from a purely logical point of view, the here pre (...) - sented logic requires nothing but a very intuitive selection of classical models of the premises, viz. the minimally abnormal ones. (shrink)

ABSTRACT The present paper offers a new approach to non-monotonic logics and their reconstruction in terms of inconsistency-adaptive logics. By applying a special technique, universally quantified formulas are assigned instances that, given the paraconsistent framework, do not cause triviality even if they conflict with knowledge deriving from other sources. From the special instances, the usual instances may be derived conditionally, viz. provided they are not contradicted by statements derived with a higher preference ranking.

This paper defends a pragmatical approach to vagueness. The vagueness-adaptive logic VAL is a good reconstruction of and an excellent, instrument for human reasoning processes in which vague predicates are involved. Apart from its proof-theory and semantics, a Sorites-treating model based on it is presented, disarming the paradox. The paper opens perspectives with respect to the construction of theories by means of vague predicates.