専門
My research fields are philosophy of mathematics and logic, mathematical logic (proof theory), and theoretical computer science (type theory). The main philosophical questions in my research are "what is a philosophical significance of proof-theory?" and "what is a proof ?". In recent years, my interest has expanded into other areas such as the Kyoto school, smart cities, robot ethics, and natural language processing.
The origin of modern philosophy of mathematics was the foundational debate in the beginning of 20th century. This debate had involved mathematicians, logicians, and philosophers. After this debate, many philosophical works have been done independently of the modern development of mathematical logic. I'm doing philosophy of logic and mathematics, mathematical logic (proof theory of higer-order theories, including j.w.w. Grigori Mints in Stanford Uni.) and theoretical computer science (type proof theory of theory, inlcuding j.w.w. Kazushige Terui in RIMS, Kyoto Uni.) in the way that they are essentially related to one another. In particular, by analyzing finitism (Hilbert), intuitionism (Brouwer), and logicism (Frege) by proof-theoretic methods, I would like to find a common base for these seemingly different positions in philosophy of mathematics. Recently, I'm working on a project to develop proof-theoretic semantics for mathematics (j.w.w. Alberto Naibo, Paris).
Moreover, I'm interested in the formalization of mathematics using Coq/Isabelle and in the question "what is a proof ?" from a computer science/natural language processing point of view (j.w.w. Koji Mineshima, Keio Uni.). These are based on my philosophical or historical interest in early Husserl's logical philosophy, for example, in his "Logische Undersuchungen" (j.w.w. Genki Uemura, Okayama Uni.).
Recently, I have been working on a project on Gaisi Takeuti's mathematical philosophy, who is one of Japan's leading logicians (, including j.w.w. Andrew Arana, Lorraine). The aim of this project is to describe his philosophical view paying attention to his philosophical background (especially the philosophy of Nishida Kitaro). The main philosophical quiestion in this project is "what is Takeuti's philosophical view of foundations of mathematcs, including proof-theory?" As a related research, I started to work on a project to apply the philosophy of self developed in the East to digital twin and VR (j.w.w. the group of Yasuo Deguchi, Kyoto Uni.). Moreover, I am also strongly interested in applying this kind of philosophy to the real world, including working with the group of Yasuo Deguchi.
Research Topics:
(i) Goedel's theorem and Hilbert's program,
(ii) Gentzen's consistency proofs,
(iii) Brouwer's proof of bar induction,
(iv) early Husserl's philosophy of logic,
(v) proof theoretic analysis of Frege's logical system,
(vi) the meaning of logical constants, proof theoretic semantics,
(vii) proof theory of impredicative subsystems of second-order arithmetic, ordinal analysis (cut-elimination, normalization theorem),
(viii) intuitionistic analysis (point-free topology),
(ix) Gaisi Takeuti's mathematical philosophy,
(x) logic of the digital twin and VR (intentionality),
(xi) alternatives to the "Master-Slave Model" in robot ethics,
(xii) industry-academia-government collaboration project on smart city,
(xiii) discourse relations in Japanese and analysis of informal proof focusing on inferential relations.
- 2025-05~Present: Cooperative Member, Center for Design of Future Symbiosis, Keio University | 慶應義塾大学, 未来共生デザインセンター, 共同研究員 (JPN)
- 2025-04~Present: Associate Professor, Graduate School of Informatics and Engineering, School of Informatics and Engineering Division of General Education, The University of Electro-Communications | 電気通信大学, 大学院情報理工学研究科、情報理工学域 共通教育部, 准教授 (JPN)
- 2022-04~2022-09: Part-time lecturer, School of Informatics and Engineering, The University of Electro-Communications | 電気通信大学, 情報理工学域, 非常勤講師
- 2018-09~Present: Associate Member, L'Institut d'Histoire et de Philosophie des Sciences et des Techniques | パリ第1大学科学史哲学研究所 (L'Institut d'Histoire et de Philosophie des Sciences et des Techniques), 連携研究員 (Associate Member) (FRA)
- 2025-02~2025-04: Associate Professor, School of Informatics and Engineering Division of General Education, The University of Electro-Communications | 電気通信大学, 情報理工学域 共通教育部, 准教授 (JPN)
- 2024-10~2025-03: Part-time lecturer, College of Arts and Sciences, The University of Tokyo | 東京大学, 教養学部, 非常勤講師 (JPN)
- 2024-04~2025-03: Part-time lecturer, School of Commerce, Waseda University | 早稲田大学, 商学部, 非常勤講師 (JPN)
- 2020-04~2025-03: Part-time lecturer, School of Arts and Letters, Meiji University | 明治大学, 文学部, 非常勤講師 (JPN)
- 2018-09~2025-03: Part-time lecturer, Faculty of Science and Engineering, Waseda University | 早稲田大学, 理工学術院, 非常勤講師 (JPN)
- 2022-10~2025-01: Project Assistant Professor, Global Research Institute, Keio University | 慶應義塾大学, KGRI, 特任助教 (JPN)
- 2022-04~2025-01: Senior Research Fellow, AaaS Bridge, inc. | 株式会社AaaS Bridge, シニアリサーチフェロー (JPN)
- 2024-04~2024-09: Part-time lecturer, School of Informatics and Engineering, The University of Electro-Communications | 電気通信大学, 情報理工学域, 非常勤講師 (JPN)
- 2023-10~2024-03: Part-time lecturer, College of Arts and Sciences, The University of Tokyo | 東京大学, 教養学部, 非常勤講師 (JPN)
- 2021-10~2024-03: Researcher, Graduate School of Letters, Kyoto University | 京都大学, 大学院文学研究科, 研究員 (JPN)
- 2018-04~2024-03: Adjunct researcher, Institute for Advanced Study, Waseda University | 早稲田大学, 高等研究所, 招聘研究員 (JPN)
- 2023-04~2023-09: Part-time lecturer, School of Informatics and Engineering, The University of Electro-Communications | 電気通信大学 情報理工学域, 非常勤講師 (JPN)
- 2023-03~2023-03: Invited Researcher (Chercheur invité), L'Institut d'Histoire et de Philosophie des Sciences et des Techniques | パリ第1大学科学史哲学研究所 (L'Institut d'Histoire et de Philosophie des Sciences et des Techniques), 招聘研究員 (Chercheur invité) (FRA)
- 2022-10~2023-03: Part-time lecturer, Faculty of Letters, Keio University | 慶應義塾大学, 文学部, 非常勤講師 (JPN)
- 2022-10~2023-03: Part-time lecturer, College of Arts and Sciences, The University of Tokyo | 東京大学, 教養学部, 非常勤講師 (JPN)
- 2021-09~2022-03: Part-time lecturer, College of Arts and Sciences, The University of Tokyo | 東京大学, 教養学部, 非常勤講師 (JPN)
- 2010-04~2022-03: Part-time lecturer, Faculty of Letters, Keio University | 慶應義塾大学, 文学部, 非常勤講師 (JPN)
- 2021-04~2021-09: Part-tme lecturer, School of Informatics and Engineering, The University of Electro-Communications | 電気通信大学, 情報理工学域, 非常勤講師 (JPN)
- 2020-09~2021-03: Part-time lecturer, College of Arts and Sciences, The University of Tokyo | 東京大学, 教養学部, 非常勤講師 (JPN)
- 2018-09~2021-03: Part-time lecturer, Faculty of Letters, Arts and Sciences, Waseda University | 早稲田大学, 文学学術院, 非常勤講師 (JPN)
- 2020-02~2020-03: Invited Researcher (Chercheur invité), L'Institut d'Histoire et de Philosophie des Sciences et des Techniques | パリ第1大学科学史哲学研究所 (L'Institut d'Histoire et de Philosophie des Sciences et des Techniques), 招聘研究員 (Chercheur invité) (FRA)
- 2019-08~2019-09: Invited Researcher (Chercheur invité), L'Institut d'Histoire et de Philosophie des Sciences et des Techniques | パリ第1大学科学史哲学研究所 (L'Institut d'Histoire et de Philosophie des Sciences et des Techniques), 招聘研究員 (Chercheur invité) (FRA)
- 2019-02~2019-03: Invited Researcher (Chercheur invité), L'Institut d'Histoire et de Philosophie des Sciences et des Techniques | パリ第1大学科学史哲学研究所 (L'Institut d'Histoire et de Philosophie des Sciences et des Techniques), 招聘研究員 (Chercheur invité) (FRA)
- 2018-04~2018-05: Part-time lecturer, College of Industrial Technology, Nihon University | 日本大学, 生産工学部, 非常勤講師 (JPN)
- 2017-04~2018-03: Associate professor (without tenure), Institute for Advanced Study, Waseda University | 早稲田大学, 高等研究所, 准教授（任期付） (JPN)
- 2017-04~2017-06: Part-time lecturer, Faculty of Science, Chiba University | 千葉大学, 理学部, 非常勤講師 (JPN)
- 2015-04~2017-03: Assistant professor, Institute for Advanced Study, Waseda University | 早稲田大学, 高等研究所, 助教 (JPN)
- 2014-04~2016-03: Part-time lecturer, Faculty of Science and Technology, Keio University | 慶應義塾大学, 理工学部, 非常勤講師 (JPN)
- 2012-04~2015-03: Post Doctoral Fellow (PD), Kyoto University, Japan Society for the Promotion of Science | 日本学術振興会, 京都大学, 特別研究員(PD) (JPN)
- 2013-04~2014-03: Part-time lecturer, Faculty of Urban Liberal Arts, Tokyo Metropolitan University | 首都大学東京, 都市教養学部, 非常勤講師 (JPN)
- 2010-04~2012-03: Assistant Professor, Graduate School of Letters (Global COE CARLS), Keio University | 慶應義塾大学, 文学研究科（グローバルCOE「論理と感性の先端的教育研究拠点」）, 特任助教 (JPN)
- 2009-04~2010-03: Part-time research fellow, Keio Advanced Research Centers, Keio University | 慶應義塾大学, 先導研究センター, 非常勤研究員 (JPN)