**Topic:**

**PARACONSISTENCY**

## Modality and Paraconsistency

By João Marcos

Paraconsistent logic was born in the vicinity of modal logic. Moreover, as every other non-classical logicians, paraconsistentists have very often flirted with modalities. The first known system of paraconsistent logic was in fact defined as a fragment of S5, in the late 40s. But a fragment of a modal system is not necessarily a modal system. I will show here, indeed, that Jaškowski’s D2 is not a modal logic, in the contemporary usual meaning of the term. By contrast, I will also show, subsequently, that any non-degenerate normal modal system is inherently paraconsistent.

Appeared in

[i.] Marta Bilkova and Libor Behounek (eds),The Logica Yearbook 2004, Filosofia, Prague, 2005, pp.213-222.

[ii.] Marcos (2005),Logics of Formal Inconsistency, Chapter 3.2, pp. 211-219. Unicamp press.

Posted by Tony Marmo
at 00:01 BST

Updated: Friday, 8 July 2005 02:21 BST