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**Topic:**

**PARACONSISTENCY**

**Update:**Today I received Jo?o Marcos' book,

*Logics of Formal Inconsistency*.

**Thanks Jo?o!!**

### Paraconsistency For Beginners

Joao Marcos' book has an important section for beginners. From page 16 to page 30, Chapter 1.0 (it would be Chapter 2 or an appendix to Chapter 1, but Jo?o liked the idea of calling it 1.0), there is a very easy exposition of what is Paraconsistent Logic. Section 2 of the same Chapter requires more attention from the reader, but by reading the first Section one is relatively prepared to understand Section 2, which is not very difficult.

So, teachers, here is my recommendation: Joao Marcos? Chapter 1.0 for your undergraduates.

February the 17

^{th}2005

Yesterday, Joao Marcos defended his PhD dissertation, as the Unicamp Portal infoms us. Here is an abstract with a link:

## Logics of Formal Inconsistency

By Joao Marcos

According to the classical consistency presupposition, contradictions have an explosive character: Whenever they are present in a theory, anything goes, and no sensible reasoning can thus take place. A logic is paraconsistent if it disallows such presupposition, and allows instead for some inconsistent yet non-trivial theories to make perfect sense. The Logics of Formal Inconsistency,LFIs, form a particularly expressive class of paraconsistent logics in which the metatheoretical notion of consistency can be internalized at the object-language level. As a consequence, theLFIs are able to recapture consistent reasoning by the addition of appropriate consistency assumptions. So, for instance, while classical rules such as disjunctive syllogism (from A and not-A-or-B, infer B) are bound to fail in a paraconsistent logic (because A and not-A could both be true for some A, independently of B), they can be recovered by anLFIif the set of premises is enlarged by the presumption that we are reasoning in a consistent environment (in this case, by the addition of consistent-A as an extra hypothesis of the rule).

The present monograph introduces theLFIs and provides several illustrations of them and of their properties, showing that such logics constitute in fact the majority of interesting paraconsistent systems from the literature. Several ways of performing the recapture of consistent reasoning inside such inconsistent systems are also illustrated. In each case, interpretations in terms of many-valued, possible-translations, or modal semantics are provided, and the problems related to providing algebraic counterparts to such logics are surveyed. A formal abstract approach is proposed to all related definitions and an extended investigation is made into the logical principles and the positive and negative properties of negation.

Keywords: Universal Logic, negation, paraconsistency, possible-translations semantics, modalities, formal philosophy.

PhD Dissertation, Cooperation Agreement between the State University of Campinas and the Technical University of Lisbon

**Note:**As the members of the Commission have offered Jo?o Marcos many suggestions, it is possible that a new revised text will appear sooner or later, though most of the Chapters have been already published as separate papers in different journals.

Posted by Tony Marmo
at 00:01 BST

Updated: Friday, 8 July 2005 02:24 BST