https://forms.gle/JqgbMG8t7WwoptZJ6

February 25th, Wednesday, 2026. 10:00-18:20 (JST)
2026年2月25日(水) 10:00-18:20 途中入退室自由

慶應義塾大学三田キャンパス東館6階G-Lab /
G-Lab, 6th floor, East Building, Mita Campus, Keio University
(7 minutes walk from JR-Tamachi, Subway Mita or Akabanebashi)
キャンパスマップ 13番の建物: https://www.keio.ac.jp/ja/maps/mita.html
Campus Map Building #13: https://www.keio.ac.jp/en/maps/mita.html

アブストラクトが下にあります/See below for Anstracts

Hirohiko Abe (*)
Risako Ando (Keio University)
Yuichiro Hosokawa (Gunma Prefectural Women's University)
Ryo Ito (Waseda University)(**)
Onyu Mikami (Tokyo Metropolitan University)
Koji Mineshima (Keio University) (**)
Mitsuhiro Okada (Keio University)(**)
Kentaro Ozeki (University of Tokyo / Keio University)
(*) Chief coordinator, (**) Co-Chairs

Center for Design of Future Symbiosis of Keio University (tentative) / 慶應義塾大学未来共生デザインセンター（予定）

同センター論理班　logic@abelatd.flet.keio.ac.jp

In 1971, the French philosopher Jacques Bouveresse (1930-2021) did a French translation of Carnap's Logical Syntax of Language (1937). This translation will be published in a few weeks, in March 2026, 55 years later. This event gives the opportunity to discuss 1) the reception of analytic philosophy in France 2) the importance of Bouveresse's work for this reception 3) the place of Carnap's thought in contemporary philosophy.

In this paper, I introduce an account of two different ways one can understand a mathematical concept before I argue that the distinction between those ways of understanding can be used to explicate a difference between Gottlob Frege's logicism and Bertrand Russell's. I first introduce Robert Brandom's inferentialism and a possible way to develop it. The idea is that Brandom distinguishes between two ways of attributing a commitment to others - de re and de dicto ways - and we can draw a corresponding distinction between two ways we acknowledge a commitment ourselves. With this distinction, I develop the account of two different ways of understanding a mathematical concept. It enables us to shed new light on the difference between the logicist programmes that the two giants put forward.

Bernays once remarked that Herbrand's theorem is "the central theorem of predicate logic". The theorem provides a kind of reduction of first-order logic to propositional logic. The result prefigures many subsequent developments in mathematical logic, establishing the equivalence of provability in a formal system with satisfiability in a particular type of finitary semantics. In this talk I will examine the connection between Herbrand's theorem and Gödel's completeness theorem for first-order logic, and assess whether Herbrand can really be said to have proved the completeness theorem. In doing so I will examine the crucial role played by Herbrand's finitism in his development of metamathematics.

This talk introduces my ongoing project on how operations (what agents can do: infer, compute, communicate, intervene) and abstract structures (models, types, semantic values, constraints) co-develop through a feedback loop. Drawing on Floridi’s notion of semanticisation and Levels of Abstraction, I argue that choosing observables is not arbitrary: model-building and evaluation refine what counts as a relevant variable, while the resulting structure constrains subsequent operations and explanations.　I then suggest that this mutual-determination idea is not only central to contemporary philosophy of information, but also illuminates key moves in the formative period of analytic philosophy, where philosophy of language, logic, and semantics were being established. I'll briefly indicate several directions this framework opens up for future research and invite feedback on how to develop the project further.

This talk reconstructs the philosophical view put forward by Robin Gandy on the finiteness and concreteness of computation and on the idealisations embedded in the notion of ‘machine computability’, and analyses what kind of mechanistic theory of reasoning is generated by Gandy’s analysis. Because we do not know what future machines will be like, we should not define the notion of “computability by a machine” e.g. in terms of computable functions, but we should instead attempt to give a characterisation of the notion of “mechanical intelligence”.

We analyze a family of connectives introduced by Stephen Read, known as "Bullet connectives". While these connectives satisfy the requirement of harmony, which is a necessary condition for a connective to be logical, they cannot be considered as logical due to a non-terminating phenomenon. Still, it is possible to assign a computational meaning to Bullet connectives, as several useful computation properties are induced by their harmonious behaviour. In this talk we discuss such computational properties, namely those concerning the fixed-point operator and recursive types in typed lambda-calculus, and conclude that this computational interpretation of the Bullet connectives is possible only if we separate the notion of types from that of propositions. So, strictly speaking, the computational interpretation we propose cannot be considered an instance of the Curry-Howard correspondence between propositions and types, and between proofs and programs.