28/05 - Tony Marmo

Comparison of Logics: Some Issues and Perspectives

Throughout the recent history of logic, many logic systems have been proposed in accordance with their proponents’ philosophical standpoints. Additionally, the comparative endeavours require that one firstly defines the sense in which one system contains the other (specially when logics of different valences are at stake). In this talk we shall present some comparative methods available in the literature and, inasmuch as possible, some pertinent issues. We shall briefly try to show how philosophical arguments/objections reflect in different results, perhaps yielding unexpected results.

One of such issues will be Suszko’s claim against many-valuedness and his reduction method. Time permitting; we shall try to present Gehrke and Walker theorem, a proven result that goes in the opposite direction of Suszko’s arguments.


14/05 - Peter Verdée

(Paraconsistent) adaptive logics: a logico-philosophical introduction

In this talk I will introduce adaptive logics as models for rational defeasible reasoning. First I will explain what defeasible reasoning is and why is useful to distinguish rational from irrational defeasible reasoning patterns. I will illustrate that there exist very different forms of defeasible reasoning (induction, abduction, vagueness, inconsistency handling, belief merging, etc.) but that they nevertheless have some formal aspects in common.

Next, I will introduce the Standard Format of Adaptive Logic (SF). I will give a short introduction to the semantics and proof theory of (SF) and will give some examples of adaptive logics within the format of the SF, with special attention for paraconsistent adaptive logics. I will argue why adaptive logics defined within SF are good unifying formalisations of many aspects of defeasible reasoning.

Finally, I will discuss some issues concerning the (computational) complexity of adaptive logics.