Christian Straßer

After majoring both in Philosophy and in Computer Science at the University of Passau in 2006, and after a short (but very pleasurable) period as teaching assistant in philosophy in Passau, Christian combined his passion for philosophy and formal systems by enrolling as a PhD-student in nonmonotonic logic at the Centre for Logic and Philosophy of Science at Gent University. Thanks to the excellent environment and the outstanding support by his supervisors Joke Meheus and Diderik Batens he obtained a PhD degree in 2011. His PhD-thesis ended up in book form as “Adaptive Logic and Defeasible Reasoning. Applications in Argumentation, Normative Reasoning and Default Reasoning” (Trends in Logic series, Springer, 2014).

After some years as a PostDoc in Gent he received the Sofja Kovalevskaja Award by the Humboldt Foundation (1.4M €), for which he was nominated by Heinrich Wansing (Bochum). The metaphoric suitcase full of research funding was spent to establish the research group in Bochum whose main focus was the study of the logical foundations of formal argumentation. That worked out pretty well in large portion due to the fact that Christian had a very lucky hand in selecting the members of the group: the PhD students Jesse Heyninck (now: postDoc at TU Dortmund) and AnneMarie Borg (now: Assistant Prof in Utrecht) (both co-supervised with Ofer Arieli) and the PostDocs Mathieu Beirlaen (now in the industry) and Pere Pardo (now PostDoc in Luxembourg). For the achievements of the group see here.

In 2020 Christian was appointed as a full professor in “Logic in Philosophy and Artificial Intelligence”. Shortly afterwards he was appointed as a BOF research professor (at the level Hoogleraar) at Ghent University, but declined the fantastic offer (with a tear in one eye) due to an even more attractive counter-offer from Bochum. The counter-offer includes the establishing of a new research group in Autumn with his partner, Dunja Seselja. You find the webpage of the group Reasoning, Rationality and Science here.

Besides the Kovalevskaja group Christian had other great PhD students, namely Sanderson Molick (co-supervised with Joao Marcos in Cotutelle between Bochum and Natal) and Stef Frijters (at UGent as a third supervisor besides Joke Meheus and Frederik van de Putte). Recently Matthis Hesse enrolled as a PhD student under the main supervision of Christian (in Bochum).

Christian’s core interests circle around non-monotonic logic and defeasible reasoning. He published on many systems of nonmonotonic logic, from adaptive logic, to default logics, KLM-systems, to formal argumentation. He also maintains the entry on nonmonotonic logic of the Stanford Encyclopedia of Philosophy. While nonmonotonic logics are typically based on a classical core logic, he is also interested in using other logics known from philosophy (such as paraconsistent and relevant logics). He is fascinated by dynamic proof theories and published on them both in the context of adaptive logics as well as formal argumentation. Together with Ofer Arieli (University College Tel Aviv-Yaffo) has has a long-term collaboration on sequent-based argumentation, with over 15 papers out to date, many together with AnneMarie Borg. Besides that he worked on the meta-theory of assumption-based argumentation and ASPIC, often together with Jesse Heyninck.

Another of his core interests is deontic logic, in particular its nonmonotonic aspects. He worked on adaptive deontic logics, default deontic logics, input-output logic, and more recently on deontic structured argumentation. Together with Agata Ciabbattoni (TU Vienna) and Leon van der Torre (Luxembourg) he recently kick-started the LoDEx project on Logical Methods on Deontic Explanation (webpage).

Finally, Christian is also interested in philosophy of science, from general philosophy of science to social epistemic aspects. In recent years the team Dunja Šešelja (Eindhoven), AnneMarie Borg (Utrecht), Daniel Fry (Heidelberg), and Christian have developed an agent-based model of scientific inquiry, which already lead to several publications.

Christian loves to collaborate, cause its fun and a way to learn a lot from great people. His collaborators include:

• AnneMarie Borg (sequent-based argumentation, structured argumentation, relevance logic),
• Diderik Batens (adaptive logic),
• Dov Gabbay (deontic logic),
• Dunja Šešelja (general philosophy of science, historical philosophy of science, agent-based models in social epistemology, formal argumentation, explanation),
• Frederik van de Putte (deontic logic, adaptive logics, proof theory),
• Jan Willem Wieland (philosophy of science),
• Jared Millson (proof theory, explanation)
• Joke Meheus (adaptive logic, deontic logic, paraconsistent logic),
• Kees van Berkel (deontic logic, sequent-based argumentation, proof theory, input-output logic)
• Laszlo Kosolovsky (philosophy of science)
• Mathieu Beirlaen (deontic logic, adaptive logics, formal argumentation),
• Matthis Hesse (formal argumentation, disputes, default logic)
• Ofer Arieli (sequent-based argumentation, logical argumentation, proof theory, relevance and paraconsistent logic ),
• Pere Pardo (deontic logic, planning),
• Sanderson Molick (first order nonmonotonic logic, first order nondeterministic semantics),

Christian is part of several groups and networks:

• Logic in Bochum Group
• The Machine Learning and Artificial Intelligence Group at RUB
• Center for Mind and Cognition
• research network Logical and Methodological Analysis of Scientific Reasoning Processes
• DFG research network “Simulations of Scientfic Inquiry”

He also is a very frequent participant in program committees, both in philosophy and artificial intelligence. E.g., since 2019 he served 27 times in program comittees.

• 2022: IJCAI22, CAKR22, SI-CLAR21, ArgXAI22, COMMA22, NMR22, AAMAS22, KR22 (senior member)
• 2021: CIAC21, ArgStrength21, CLAR21, FCR21, AAMAS/KRR21, IJCAI21
• 2020: NMR20, IJCAI20, COMMA20, KR20, Bayes by the Sea 2020, CLAR20, DEON20/21, PhDs in Logic 2020
• 2019: Bayes by the Sea 2019, ExLog2019 at UCLouvain, DARE19, IJCAI19 (elected as Distinguished Program Committee member), ABM-Phil19

For more entries see his CV.