Date : October 5th 2024
Venue : Room 302 of the Philosophy Department at the Shuiyuan Campus (水源學校), National Taiwan University
Schedule :
9:50-10:00 Opening remarks
10:00-11:00 Shawn Standefer (NTU) Relevant deontic logic reconsidered
11:00-12:00 Takuro Onishi (Kyoto) Logic of mutual intentionality
12:00- 1:30 Lunch
1:30- 2:30 Ren-June Wang (Chung Cheng) Modal epistemic logic and its logical omniscience problem
2:30- 3:30 Hitoshi Omori (Tohoku) A note on universal modality in FDE
3:30- 4:00 Break
4:00- 5:00 Katsuhiko Sano (Hokkaido) How can we interpret distributed knowledge via Artemov and Protopopescu's intuitionistic epistemic logic?
Abstracts:
Shawn Standefer (National Taiwan University)
Title: Relevant deontic logic reconsidered
Abstract: Goble (1999) presented some relevant deontic logics and argued that relevant logics provided one reason to reject the D axiom. This is surprising, as the D axiom is typically taken to be distinctive of deontic logic. I will argue that Goble’s arguments do not provide good reason for rejecting the D axiom. Further, I will discuss Goble’s logics and highlight the ways in which they are not minimal. This will then lead to some proposals for basic deontic systems for relevant logics.
Takuro Onishi (Kyoto University)
Title : Logic of Mutual Intentionality
Abstract : This talk presents ongoing research that builds upon the collaborative project “Logic of Presence” with Deguchi, Yagisawa, Akiyoshi and Shirakawa, focusing on the formal logic of mutual intentionality. The central question we address is: What does it mean for artificial agents—such as AI or robots—to exhibit a form of presence that resembles human presence? We believe that one of the sufficient conditions for such presence is mutual intentionality. Mutual intentionality refers to the phenomenon where agents direct intentional states towards one another and are aware of this mutual directionality. In this talk I extend Priest’s modal Meinongian theory of intentionality and present a logic of mutual intentionality on relevant epistemic logic with public announcement and common knowledge, exploring a recursive structure of mutual intentionality.
Ren-June Wang (Chung Cheng University)
Title: Modal epistemic logic and its logical omniscience problem
Abstract: It is well known that modal epistemic logic suffers from the so-called logical omniscience problem that the modeled agent knows all the logical consequences of what is known. As part of this talk, we will survey the possible epistemic readings of modal formulas and locate the one for which the logical omniscience problem is indeed a problem. As a result, to achieve non-logical omniscience, we suggest that the expressive power of modal logic needs to be increased. We need an explicit temporal index for every modal operator occurrence to indicate the reasoning time that the modeled agent needs to consume in order for the agent to have the modeled epistemic attitude toward the formulas to be qualified by the modal operator.
Hitoshi Omori (Tohoku University)
Title : A note on universal modality in FDE
Abstract : In a recent paper, Shawn Standefer and Rohan French investigated the effect of adding universal modality to intuitionistic logics as well as relevant logics. Motivated by their work, especially emphasizing the ``classical'' behaviour of the universal modality, this small note observes some results concerning the effect of adding the universal modality to FDE by making some connections to one of the approaches to paraconsistent logic via the consistency operator.
Katsuhiko Sano (Hokkaido University)
Title: How can we interpret distributed knowledge via Artemov and Protopopescu's intuitionistic epistemic logic?
Abstract: Artemov and Protopopescu (2016) introduced a Brouwer-Heyting-Kolmogorov (BHK) interpretation of the knowledge operator to define the intuitionistic epistemic logic IEL, where the axiom A -> KA is accepted but the axiom KA -> A is rejected. Under this umbrella of IEL, this talk investigates how we can interpret the notion of distributed knowledge in the literature on epistemic logic. Based on an interpretation, we provide a BHK interpretation of the distributed knowledge operator to define the intuitionistic epistemic logic with distributed knowledge DIEL. We construct a Hilbert system and a cut-free sequent calculus for DIEL and show that they are sound and complete for the intended Kripke semantics.