Table of Contents

Welcome to the homepage of the Research Group for Logic in Philosophy and Artificial Intelligence (LogPhiAI) at the Institute for Philosophy II, Ruhr-University Bochum.

Description and Impact of the Group

The group has been originally funded under the name Research Group for Non-Monotonic Logic and Formal Argumentation by a Sofja Kovalevskaja Award of the Alexander von Humboldt-Foundation from September 2014 to September 2019. One research focus of the group is nonmonotonic logic as a formal model of defeasible reasoning. The group actively contributes research in the areas of

  • formal argumentation theory
  • adaptive logic
  • deontic logic, and
  • non-classical logic.

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Members and Guests

Current Members


Currently the group hosts the following researchers:

  • Christian Straßer (permanent student aka professor, office GA 3/39)

    pass2.png Christian is working in non-monotonic logics, defeasible reasoning, argumentation, deontic and adaptive logics, and agent-based models. His CV is here, his list of publications here and his talks here. For more information take a look at his academic homepage. His speaking hours are every Wednesday from 10:00–12:00 best write him a mail first. You can write him at

  • Sam Sanders (PostDoc researcher)

    Sam-Sanders.jpg Together with Dag Normann, Sam studies the logical and computational properties of the uncountable. Their study of basic mathematical facts pertaining to the Riemann integral or the uncountability of the reals has unveiled a vast new world, often completely different from the state-of-the-art in the countable world, i.e. Reverse Mathematics and Turing computability theory.

  • Sanderson Molick (PhD student, Natal and Bochum)

    s200_sanderson.molick.jpg Sanderson is doing a PhD under the supervision of Joao Marcos and Christian. His current research is focused on critically exploring logical anti-exceptionalism: e.g., the role of the a priori and the question of what is logical data and what roles it plays in logical theory choice. He also investigates problems many-valued logics, in particular in first-order and non-monotonic contexts. He will defend his PhD in April 2021.


  • Christiane Dahl (admin, Building GA 04/42)

    letterbox_400__trans_18c974cb771c27d50886ec64e546607f_letterbox_650__trans_74c76e999bc593d614f4b18f45adddd4_foto_cd.jpg Christiane is running the offices of Markus Werning, Sen Cheng, and Christian.

Previous local PhD students

  • AnneMarie Borg (Post-Doc, Utrecht University)

    s200_annemarie.borg.jpg AnneMarie has been working on Justification Logic and Logical Argumentation. Her academic profile can be found here. She finished her PhD under the supervision of Christian and Ofer Arieli in 2019. It contains various contribution to the logical foundations of sequent-based and logical argumentation, such as investigations in extending sequent-based argumentation with defeasible assumptions, or investigations in issues of relevance.

  • Jesse Heyninck (Post-Doc, TU Dortmund)

    jesse.jpg Jesse finished his PhD under the supervision of Christian and Ofer Arieli in January 2019. He’s especially interested in combinations of defeasible reasoning forms and argument strength (here’s a description of his research project). His academia homepage can be found here.

Previous PostDocs

Associate Members

  • Dunja Šešelja (Assistant Professor, TU Eindhoven)

    s200_dunja._e_elja.jpg Dunja is working in the philosophy of science. Her research topics include epistemic and methodological aspects of scientific inquiry, with a special emphasis on the context of scientific diversity. Her recent research mainly focuses on agent-based modeling of scientific inquiry and the question of its epistemic function. Find more information on her academic homepage.

  • Daniel Frey (Master Student in Economics at University Heidelberg)

    s200_daniel.frey.jpg Daniel frequently collaborates with us on agent-based models. He is equally interested in the implementation side of things (e.g., NetLogo) and the conceptual considerations underlying formal models. He is finishing his master thesis investigating the Kevin Zollman’s notion of transient diversity.

Previous Guests

  • Jones Becker Arenhart

    Jonas-Arenhart.jpg Jonas is working on an anti-exceptionalist approach to logic, connecting the ‘logic as models approach’ with current pragmatic oriented understanding of models in philosophy of science. He is also interested in naturalism in philosophy in general.

  • Ofer Arieli (Professor of Computer Science at the School of Computer Science, The Academic College of Tel-Aviv)


Ofer Arieli co-supervised the PhDs of AnneMarie and Jesse. We often collaborate on Sequent-Based Argumentation (see e.g., Sequent-based logical argumentation - IOS Press). Recently a VIP-visiting grant for 2018 was granted to Ofer by the Research School PLUS (RUB).

  • Lorenz Demey (prof. in philosophical logic at KU Leuven)

    lorenz.jpg Lorenz was visiting us from the beginning of July to the end of September 2017. His current research is focused on logical geometry; his other research interests include the philosophies of science, language and mathematics, and the mathematical environment of modal logic (algebra, topology, etc.). His webpages can be found at and KU Leuven who’s who - Lorenz Demey.

  • Stef Frijters (PhD student, Ghent University)


Stef is a PhD student of Joke Meheus, Frederik Van De Putte and Christian. His special interest is in bringing deontic logic closer to real-life applications such as medical ethics. He will defend his PhD in March 2021.

  • Vlasta Sikimic (Postdoc, University of Belgrade)


Vlasta co-organized the conference Formal Models of Scientific Inquiry (link) with us. One of her interests concerns the efficiency of knowledge acquisition in laboratory-based research (e.g., in the Fermilab). Besides that she has published on formal logic (e.g., structurality, display calculi) and animal ethics.


Workshops and Conferences

We have organized the following workshops and conferences:

  1. Agent-Based Models in Philosophy – Prospects and Limitations (2019)
    Organized by: Gergor Betz (KIT, Karlsruhe), Dunja Seselja (LMU, Munich), and Christian Straßer (RUB, Bochum)
    Keynotes: Corinna Elsenbroich (Surrey), Rainer Hegselmann (Bayreuth), Cailin O’Conner (Irvine), Samuli Reijula (Tampere), Daniel Singer (University of Pennsylvania), Kevin Zollman (Carnegie Mellon)
  2. Bridging the Gap between Formal Argumentation and Actual Human Reasoning (2018)
    Organized by: Ofer Arieli (Tel Aviv), AnneMarie Borg (RUB), Marcos Cramer (Dresden), Jesse Heyninck (RUB), Pere Pardo Ventura (RUB), Christian Straßer (RUB)
    Keynotes: Ofer Arieli (Tel Aviv), Federico Cerutti (Cardiff), Antonis Kakas (Cyprus), Chris Reed (Dundee), Alice Toniolo (St.-Andrews), Serene Villata (INRIA, Sophia Antipolis), Adam Wyner (Swansea)
  3. Formal Models of Scientific Inquiry (2017)
    Organized by: AnneMarie Borg (RUB), Dunja Seselja (RUB), Vlasta Sikimic (Belgrade), and Christian Straßer (RUB),
    Keynotes: Gregor Betz (KIT, Karlsruhe), Leah Henderson (Groningen), Jason McKenzie Alexander (LSE, London)
  4. Argument Strength (2016)
    Organized by: Mathieu Beirlaen (RUB), AnneMarie Borg (RUB), Jesse Heyninck (RUB), Pere Pardo (RUB), Dunja Seselja (RUB), and Christian Straßer (RUB),
    Keynotes: Gerhard Brewka (Leipzig), Dov Gabbay (London), Gabriele Kern-Isberner (Dortmund), Beishui Liao (Zhejiang), Henry Prakken (Utrecht), Leon Van Der Torre (Luxembourg)
  5. Logic in Bochum (2016)
    Organized by: AnneMarie Borg (RUB), Mathieu Beirlaen (RUB), Jesse Heyninck (RUB), Pere Pardo (RUB), Dunja Seselja (RUB), and Christian Straßer (RUB),
    Keynotes: Joao Marcos (Natal), Gabriella Pigozzi (Paris), Niko Strobach (Münser), Allard Tamminga (Utrecht/Groningen)