LLAL@GSIS (XIV)

Aim

The aim of this edition of LLAL@GSIS meeting is to discuss and exchange new ideas and recent developments related to philosophical logic and philosophy of logic, broadly construed. Given that the meeting is planned on the occasion of Mahan Vaz's visit to Sendai, some special emphasis is laid on topics related to paraconsistency.

Date & Venue

• Date: June 12, 2026.

• Venue: Lecture Room on 3F , Graduate School of Information Sciences, Tohoku University.  

Speakers

• Hitoshi Omori (Tohoku University)

• Mahan Vaz (University of Campinas & Ruhr University Bochum)

Program

17:00--17:45 Hitoshi Omori "Is 0 untruth or falsity?"

17:45--18:00 Break 

18:00--19:00 Mahan Vaz "Evidence in the Logics of Evidence and Truth" 

Abstracts

Hitoshi Omori: While model-theoretic semantics for paraconsistent logic sometimes treats the value 0 (or F) as untruth, at other times it treats it as falsity. This presentation investigates these competing perspectives by drawing on the divide between unilateralism and bilateralism.

-----

Mahan Vaz: The Logics of Evidence and Truth (LETs) are systems proposed by Carnielli and Rodrigues (2019) which expand Nelson's logic N4 by a consistency operator. The idea is that such logics can deal with the notions of evidence and truth at the same time. I propose in this talk to investigate the notion of evidence used as the background concept for the construction of the aforementioned logics. I argue that we could move towards a stronger notion of evidence than originally presented by Carnielli and Rodrigues, by bringing in a relevance connection between evidence and the proposition it supports. I also present another system in the tradition of the LETs based on the positive fragment of relevant logic R.

-----

Acknowledgement

This workshop is partially supported by the Graduate School of Information Sciences, Tohoku University.