Ryota Akiyoshi

J-GLOBAL         Last updated: Apr 2, 2019 at 10:11
Ryota Akiyoshi
Waseda University
Institue for Advanced Study
Job title
Adjunct Researcher
PhD (Philosophy)(Keio University)
Other affiliation
Keio University
Research funding number


My research fields are philosophy of mathematics and logic, mathematical logic (proof theory), and theoretical computer science (type theory). The main philosophical question in my research is "what is a proof ?".

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) and theoretical computer science (type theory) 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.

More recently, I'm interested in the formalization of mathematics using Coq or Minlog and in the question "what is a proof ?" from this point of view too. These are based on my philosophical or historical interest in early Husserl's logical philosophy (for example, his "Logische Undersuchungen"). Moreover, I started to work on Gaisi Takeuti's finitism behind his proof theoretic works and cyber security as an application of proof theory.

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),
(xi) Gaisi Takeuti's finitism,
(x) cyber security as an application of proof theory.

Research Areas


Academic & Professional Experience

Sep 2018
Part-time lecturer, Faculty of Science and Engineering, Waseda University
Sep 2018
Part-time lecturer, Faculty of Letters, Arts and Sciences, Waseda University
Sep 2018
Associate Member, L'Institut d'Histoire et de Philosophie des Sciences et des Techniques
Apr 2018
Adjunct researcher, Institute for Advanced Study, Waseda University
Apr 2010
Part-time lecturer, Faculty of Letters, Keio University
Feb 2019
Mar 2019
Invited Researcher, L'Institut d'Histoire et de Philosophie des Sciences et des Techniques
Apr 2018
May 2018
Part-time lecturer, College of Industrial Technology, Nihon University
Apr 2017
Mar 2018
Associate professor (without tenure), Institute for Advanced Study, Waseda University
Apr 2017
Jun 2017
Part-time lecturer, Faculty of Science, Chiba University
Apr 2015
Mar 2017
Assistant professor, Institute for Advanced Study, Waseda University
Apr 2014
Mar 2016
Part-time lecturer, Faculty of Science and Technology, Keio University
Apr 2012
Mar 2015
Post Doctoral Fellow (PD), Kyoto University, Japan Society for the Promotion of Science
Apr 2013
Mar 2014
Part-time lecturer, Faculty of Urban Liberal Arts, Tokyo Metropolitan University
Apr 2010
Mar 2012
Assistant Professor, Graduate School of Letters (Global COE CARLS), Keio University
Apr 2009
Mar 2010
Part-time research fellow, Keio Advanced Research Centers, Keio University

Awards & Honors

Nov 2014
The Japan Association for Philosophy of Science Research Award, The Japan Association for Philosophy of Science
Winner: Ryota Akiyoshi, Yuta Takahashi
Oct 2009
The Japan Association for Philosophy of Science Research Award, The Japan Association for Philosophy of Science

Books etc

Consistency proofs of arithmetic: Introduction to proof-theory (in Japanese)
Ryota Akiyoshi (Part:Joint Work, Consistency proofs by cut-eliminatiom methods)
Kyoritsu Publisher   2019   
Philosophical Logic: Current Trends in Asia – Proceedings of AWPL-TPLC 2016
Ryota Akiyoshi, Yuta Takahashi (Part:Contributor, Contentual and Formal Aspects of Gentzen’s Consistency Proofs (refereed))
Springer Verlag   Nov 2017   ISBN:9789811063541
Yokuwakaru Tetsugaku and Shisou (textbook on philosophy)
Ryota Akiyoshi (Part:Contributor, 「論理学」(article of "logic"))
Minerva Publisher   2019   

Published Papers

Ryota Akiyoshi
Proceedings of the XXIII World Congress of Philosophy   56 5-9   2018   [Refereed]
Ryota Akiyoshi
WoLLIC 2018 25th Workshop on Logic, Language, Information and Computation, Lecture Notes in Computer Science   10944 77-90   Jul 2018   [Refereed]
Ryota Akiyoshi
The Mints' memorial issue of the IfCoLog Journal of Logics and their Applications   4(4) 867-884   May 2017   [Refereed][Invited]
Ryota Akiyoshi, Kazushige Terui
First International Conference on Formal Structures for Computation and Deduction (FSCD), Leibniz International Proceedings in Informatics      Jun 2016   [Refereed]
Ryota Akiyoshi, Grigori Mints
Archive for Mathematical Logic   55(3) 593-603   May 2016   [Refereed]


Takeuti’s proof-theory in the context of the Kyoto school
Ryota Akiyoshi and Andrew Arana
to be submitted      Feb 2019
Towards proof-theoretic semantics for second-order logic
Ryota Akiyoshi and Alberto Naibo
in preparation      2019
Husserl on Logic without a Humean Worry
Ryota Akiyoshi and Genki Uemura
in preparation      2019
Takeuti’s finitism and ordinal-theoretic proofs of consistency
Ryota Akiyoshi and Andrew Arana
in preparation, 30 pages      2019
“Proofs as Programs” in Parameter-Free Fragments of System F
Ryota Akiyoshi
submitted, 17 pages      2018

Conference Activities & Talks

飯田氏の論理学・数学の哲学をめぐって [Invited]
Ryota Akiyoshi
飯田隆先生・丹治信春先生古希記念ワークショップ:言語・論理・知識   Mar 2019   
On Takeuti's Finitism [Invited]
Ryota Akiyoshi
Atelier : perspectives philosophiques sur des théories formelles (Institut d'histoire et de philosophie des sciences et des techniques)   Feb 2019   
Takeuti’s Finitism Revisited [Invited]
Ryota Akiyoshi
Theory Seminar (Swansea University, Department of Computer Science)   Feb 2019   
Disagreement on Brouwer’s Argument for Bar Induction
Ryota Akiyoshi
Workshop on Philosophy of Logic "Around Norm, Rule and Disagreement" (Keio University   Jan 2019   
Towards a new development of formalism: Gaisi Takeuti's philosophy [Invited]
Ryota Akiyoshi
148th CAPE Lecture (Kyoto University)   Nov 2018   

Association Memberships