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15th International Conference on Deontic Logic and Normative Systems (DEON 2020/21)

MCMP/LMU Munich, 21-24 July 2021

Idea & Motivation

The biennial DEON conferences are designed to promote interdisciplinary cooperation amongst scholars interested in linking the formal-logical study of normative concepts, normative language and normative systems with computer science, artificial intelligence, linguistics, philosophy, organization theory and law.
In addition to the general theme of the DEON conferences, DEON 2020/21 will encourage a special focus on the topic: Norms in Social Perspective.

The conference will be held online.


Keynote speakers

There have been fourteen previous DEON conferences: Amsterdam, December 1991; Oslo, January 1994; Sesimbra, January 1996; Bologna, January 1998; Toulouse, January 2000; London, May 2002; Madeira, May 2004; Utrecht, July 2006; Luxembourg, July 2008; Fiesole, July 2010; Bergen, July 2012; Ghent, July 2014; Bayreuth, July 2016; and Utrecht, July 2018.






Call for Papers

Submission Details

Co-located Event




All times are CEST

Wednesday 21st July

Thursday 22nd July

Friday 23rd July

Saturday 24th July

10:30 Opening words
10:45-11:45 Keynote
Sonja Smets. The Logical Dynamics of Social Norms

Chair: Frederik Van De Putte

Timo Lang. A Reduction in Violation Logic

Chair: Xavier Parent

Antonino Rotolo and Guido Governatori. Is Free Choice Permission Admissible in Classical Deontic Logic?

Chair: Chenwei Shi

Emiliano Lorini. Logics of Evaluation.

Chair: Fenrong Liu

Takahiro Sawasaki and Katsuhiko Sano. Term-Sequence-Dyadic Deontic Logic

Chair: Xavier Parent

Maya Olszewski, Xavier Parent and Leendert van der Torre. Input/Output logic with a consistency check - the case of permission

Chair: Chenwei Shi

11:45-12:00 Short Break Short Break Short Break Short Break
12:00-12:30 Kees van Berkel, Leendert van der Torre and Dov Gabbay. If you want to smoke, don't buy cigarettes: near-anankastics, contexts, and hyper modality

Chair: Norbert Gratzl

Stef Frijters and Thijs De Coninck. The Manchester Twins: Conflicts Between Directed Obligations

Chair: Réka Markovich

Alexander Steen. Goal-Directed Decision Procedures for Input/Output Logics

Chair: Alessandro Giordani

Tim Lyon and Kees van Berkel. The Varieties of Ought-implies-Can and Deontic STIT Logic

Chair: Stef Frijters

12:30-13:00 Maya Olszewski, Agata Ciabattoni, Kees van Berkel, Francesca Gulisano and Elisa Freschi. The Gentle Murder Paradox in Sanskrit Philosophy

Chair: Norbert Gratzl

Guido Governatori, Silvano Colombo Tosatto and Antonino Rotolo. A Defeasible Deontic Logic for Pragmatic Oddity

Chair: Réka Markovich

Agata Ciabattoni and Bjoern Lellmann. Sequent Rules for Reasoning and Conflict Resolution in Conditional Norms

Chair: Gabriella Pigozzi

Tiziano Dalmonte, Charles Grellois and Nicola Olivetti. Proof systems for the logics of bringing-it-about

Chair: Stef Frijters

13:00-13:30 Juliano Maranhao and Giovanni Sartor. Interpretive Normative Systems

Chair: Norbert Gratzl

Aleks Knoks. Moral principles: Hedged, contributory, mixed

Chair: Réka Markovich

Federico L.G. Faroldi, Meghdad Ghari, Eveline Lehmann and Thomas Studer. Impossible and Conflicting Obligations in Justification Logic

Chair: Gabriella Pigozzi

Karl Nygren. Deontic logic based on inquisitive semantics

Chair: Stef Frijters

13:30-15:00 Lunch break + Social gathering
Lunch break + Social gathering
Lunch break + Social gathering
Lunch break + Social gathering
15:00-15:30 Alessandro Giordani. Reason-based Deontic Logic

Chair: Olivier Roy

Daniela Schuster. Forms and Norms of Indecision in Argumentation Theory

Chair: Paul McNamara

Daniela Glavanicova and Matteo Pascucci. Axiomatizing norms across time and the Paradox of the Court

Chair: Ilaria Canavotto

Valentin Goranko. How deontic logic ought to be: towards a many-sorted framework for deontic logic

Chair: Huimin Dong

15:30-16:00 Franz Dietrich. Rationality through reasoning and automatic psychology


Chair: Olivier Roy

Franz Dietrich. Rationality through reasoning and automatic psychology

Chair: Paul McNamara

Réka Markovich and Olivier Roy. A Logical Analysis of Freedom of Thought

Chair: Ilaria Cavanotto

Edgar Avendaño-Mejía and Yolanda Torres-Falcón. The roles of authority and norm-addressees in deontic puzzles

Chair: Huimin Dong

16:00-16:30 Thijs De Coninck and Frederik Van De Putte. The Original Position: A Logical Analysis

Chair: Olivier Roy

Christian Strasser and Pere Pardo. Prioritized Defaults and Formal Argumentation

Chair: Paul McNamara

Social Gathering
Pablo Castro, Valentin Cassano, Raul Fervari and Carlos Areces. Deontic Action Logics via Algebra

Chair: Huimin Dong

16:30-17:00 Social Gathering
Break Break Closing words by Jan Broersen, Chair of DEON Steering Committee

+ Social gathering

17:00-18:00 Keynote
Shyam Nair. Reasons-Based Theories of Obligation and Optimality.

Chair: Paul Portner

Marcia Baron. Recklessness and Negligence in the Criminal Law.

Chair: Alessandra Marra

18:00-18:30 Social gathering
Social gathering


Keynotes’ Abstracts

Marcia Baron, Recklessness and Negligence in the Criminal Law.

Criminal law theorists debate whether negligence should suffice for criminal liability. Put differently, should acting negligently ever be enough to supply the mens rea, or culpability, component, required for criminal conviction? Everyone agrees that recklessness should suffice, but there is disagreement about negligence.
The debate is marred by unclarity about just how negligence differs from recklessness. It is not unusual to have the experience I recently had when arguing that negligence should suffice: someone in the audience says, 'But that isn’t really negligence! That example you just gave is really an example of recklessness.'
The disagreement is surprising because the parties to the debate all claim to be relying on the definitions of negligence and recklessness in the Model Penal Code. However, the definitions are dense and the implications are not always obvious. In addition, some parts of the definitions are often neglected by those offering summaries of what, according to the MPC, the difference between negligence and recklessness is.
In my presentation, after first explaining the mens rea requirement so as to provide the context for the debate, I seek to shed light on what, according to the MPC definitions, the difference between negligence and recklessness is. I then indicate some implications for the controversy concerning whether negligence should suffice for criminal liability.


Emiliano Lorini, Logics of Evaluation.

We present a family of logics of evaluation which clarify the relationship between knowledge, values and preferences of multiple agents in an interactive setting. Evaluation is a fundamental concept for understanding how an ethical agent's decision is affected by her values. We present complete axiomatics for these logics as well as a dynamic extension by the concept of value expansion. We show that value expansion indirectly affects the agents' preferences by inducing a preference upgrade operation.


Shyam Nair, Reasons-Based Theories of Obligation and Optimality.

It is common in certain circumstances for philosophers and logicians to conflate what is obligatory or required with what is optimal or ought to be done. But it is a by now familiar thought that these notions should be separated. Terms such as 'must' and 'have to' are most naturally used to express obligations or requirements. Terms such as 'ought' and 'should' do not express requirements. Instead they are used to express a kind of optimality. Paul McNamara and other logicans have done much to improve our understanding of these notions (as well as various other related notions) within a broadly value- or preference-based deontic logic framework. But comparatively less work has been done exploring these issues in the broadly imperatival or reasons-based deontic logic tradition. A notable exception is a recent paper by Robert Mullins. This talk discusses various choice points and generalization of Mullin's framework. The aim is to highlight that there are many different frameworks that deserve our attention and provide a preliminary assessment of the costs and benefits of each.


Sonja Smets, The Logical Dynamics of Social Norms

The flow of information is what drives our information society of interconnected agents capable of reasoning, communication, and learning. In this context we are interested in the logical study of how information flows in social networks by focusing on the spread of behaviors, ideas, and the adoption of norms across a social network. With respect to the study of social norms, our aim is to design a logical model that can give an adequate description of agents being influenced to adopt a new norm. This refers to situations as described by C. Bicchieri in [1]: "if people believe that a sufficient large number of others uphold a given norm, then, under the right conditions, they will conform to it". We will focus on these triggers of being persuaded to adopt a new norm, which are here stated in terms of a "sufficient large number of others", or "enough people", upholding the norm. We will capture these triggers for adopting norms in a qualitative logical framework and model the diffusion process as well as the long-term informational evolution of our networks. For this presentation, which is based on ongoing work with A. Baltag and on the work presented in [2], we will make use of the tools of Dynamic Epistemic Logic as well as Modal Mu-Calculus.
[1] C. Bicchieri, The Grammar of Society, The Nature and Dynamics of Social Norms, Cambridge University Press, 2006.
[2] A. Baltag, Z. Christoff, R. K. Rendsvig, S. Smets, Dynamic Epistemic Logics of Diffusion and Prediction in Social Networks, Studia Logica, 107(3):489–531,

Call for Papers

General Themes

We invite papers concerned with the following topics (non-exclusive list):

  • the logical study of normative reasoning, including formal systems of deontic logic, defeasible normative reasoning, logics of action, logics of time, and other related areas of logic
  • the formal analysis of normative concepts, normative systems (and their dynamics)
  • the formal specification of aspects of norm-governed multi-agent systems and autonomous agents, including (but not limited to) the representation of rights, authorization, delegation, power, responsibility and liability
  • the normative aspects of protocols for communication, negotiation and multi-agent decision making
  • the formal analysis of the semantics and pragmatics of deontic and normative expressions in natural language, including modals, imperatives, deontic verbs and adjectives, and discourse particles
  • advances in formal models of context and discourse structure that aim to explain the use of deontic expressions in natural language, and their significance for communication, action and social structures
  • the formal representation of legal knowledge
  • the formal specification of normative systems for the management of bureaucratic processes in public or private administration
  • applications of normative logic to the specification of database integrity constraints
  • game theoretic aspects of deontic reasoning
  • emergence of norms, including its logical and computational representation
  • deontic paradoxes and their philosophical and linguistic import
  • the connection between argumentation theory and normative reasoning, including the role of reasons and justifications

Special Focus: “Norms in Social Perspective”

While deontic logic is still often approached as the logic of objective, agent-independent notions of obligation, permission, and prohibition, there is a growing body of literature on the role of groups, social interaction, and networks in our norms and normative reasoning. The social perspective plays a role in our deontic reasoning in at least three different ways. First, it determines the way norms are adopted and updated. How individual and group agents relate to one another (e.g. via a social network or as part of an institution) is essential for the norms these agents endorse, and for the way their norms change. Second, social interaction is essential for the way normative language is used and interpreted: deontic terms can acquire meaning via social conventions, and we use deontic terms to communicate our ethical stances to one another, and to convince each other of the rationality of certain choices. Third, the social dimension is also essential in the way we evaluate norms: often, obligations cannot be properly explained in terms of a single normative code or one individual agent’s attitudes. Instead, one needs to refer to the preferences, goals, and norms of several agents, and to lift these to the group level in order to specify what ought to be done.

The conference is open to any contribution concerning deontic logic and normative systems. We however particularly welcome all contributions that relate to the special theme. Some examples of questions that can be addressed in connection with the theme are:

  • What is the logical structure of social obligations and permissions? How do they relate to individual obligations and permissions?
  • How should one interpret the various paradoxes of Standard Deontic Logic from the viewpoint of a social, interactive use of deontic terms?
  • What type of norms govern our interaction and in particular, communication? Can we study these norms using (variants of) existing deontic logics?
  • How are we to analyse the natural language forms that encode social relations, such as honorifics, address terms and allocative markers, in semantic and pragmatic theory?
  • How do social relations, whether grammatically encoded or not, affect the interpretation of deontic and other modal expressions in natural language?
  • How does norm change and norm update behave in the presence of networks?
  • How do different perspectives on the evaluation of norms in social terms (e.g. individual vs. social, “flat groups” vs. networks of agents, in terms of explicit agreements vs. in terms of a social choice function) cash out in terms of formal logics?
  • Can we suitably combine deontic logics and formal frameworks for reasoning about networks? What formal and philosophical hurdles should first be taken in order to merge these two lines of research?
  • Can deontic terms such as must, ought, may acquire their meaning via social conventions? Could such a meaning acquisition be captured via a combination of logical and game theoretic tools?
  • How do rights and duties of institutions relate to those of their members from a legal and political perspective? How can this relation be represented formally?top

Submission Details

We open an extra call for a small number of additional papers. With this extra call, we hope to attract authors who did not already contribute to last year's publication round.
Authors are invited to submit an original, previously unpublished, short research paper pertaining to any of the DEON topics.
The paper should be in English, anonymized, and should be no longer than 15 pages (including notes and appendix, but excluding bibliography). The paper must be formatted according to the LaTeX specification that can be downloaded here. The first page should contain an abstract of no more than ten lines.
The submission of the abstract must precede the submission of the paper. Authors should submit electronically using EasyChair.

Each submitted paper will be carefully peer-reviewed by a panel of PC members based on originality, significance, technical soundness, and clarity of exposition and relevance for the conference. For each accepted paper, at least one author is required to register for the conference and should plan to present the paper.

We strongly encourage women and other members of under-represented groups in academia to


The proceedings are published with College Publications. They are accessible online at Revised versions of selected papers from the conference will subsequently be published in a special issue of the Journal of Logic and Computation (Oxford University Press).

topCo-located Event

DEON 2020/21 will be co-located with the Summer School on Mathematical Philosophy for Female Students, to be held also online on 19-23 July 2021.


Please register via our online registration tool before 20th July, 5 pm CEST. We are happy to announce that there will be no registration fees for DEON 2020/21.

DEON 2020/21 is funded by the Deutsche Forschungsgemeinschaft (DFG, GermanResearch Foundation) [446508593], which is gratefully acknowledged.

Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) – [446508593]


Chairs of the Program Committee

Fenrong Liu, Tsinghua University

Alessandra Marra, MCMP/LMU Munich

Paul Portner, Georgetown University

Frederik Van De Putte, University of Rotterdam and Ghent University

Local Organizing Committee

Alessandra Marra, MCMP/LMU Munich (chair of the local organizing committee)

Norbert Gratzl, MCMP/LMU Munich

Hannes Leitgeb, MCMP/LMU Munich

 topProgram Committee DEON 2020/21
Thomas Ågotnes (University of Bergen)
Maria Aloni (University of Amsterdam)
Christoph Benzmüller (Freie Universität Berlin)
Jan Broersen (Utrecht University)
Mark Brown (Syracuse University)
Ilaria Canavotto (University of Amsterdam)
Fabrizio Cariani (University of Maryland, College Park)
Jose Carmo (University of Madeira)
Ivano Ciardelli (MCMP/LMU Munich)
Roberto Ciuni (University of Padova)
Cleo Condoravdi (Stanford University)
Robert Demolombe (ONERA)
Huimin Dong (Zhejiang University)
Hein Duijf (Vrije Universiteit Amsterdam)
Federico Faroldi (Ghent University)
Stephen Finlay (University of Southern California)
Guido Governatori (CSIRO)
Davide Grossi (University of Groningen)
Andreas Herzig (CNRS, IRIT, Univ. Toulouse)
John Horty (University of Maryland)
Magdalena Kaufmann (University of Connecticut)
Piotr Kulicki (John Paul II Catholic University of Lublin)
Beishui Liao (Zhejiang University)
Juliano Maranhao (University of São Paulo)
Réka Markovich (University of Luxembourg)
Joke Meheus (Ghent University)
John-Jules Meyer (Utrecht University)
Robert Mullins (Queensland University)
Xavier Parent (TU Wien)
Gabriella Pigozzi (Université Paris-Dauphine)
Martin Rechenauer (MCMP/LMU Munich)
Antonino Rotolo (University of Bologna)
Olivier Roy (Universität Bayreuth)
Chenwei Shi (Tsinghua University)
Audun Stolpe (Norwegian Defence Research Establishment FFI)
Christian Strasser (Ruhr-University Bochum)
Allard Tamminga (University of Groningen)
Paolo Turrini (University of Warwick)
Peter Vranas (University of Wisconsin-Madison)
Malte Willer (University of Chicago)
Tomoyuki Yamada (Hokkaido University)
Leon van der Torre (University of Luxembourg)

DEON Steering Committee
Jan Broersen (Utrecht University) - Chair
John Horty (University of Maryland) - Vice Chair
Christoph Benzmüller (Freie Universität Berlin)
Cleo Condoravdi (Stanford University)
Melissa Fusco (Columbia University)
Beishui Liao (Zhejiang University)
Juliano Maranho (University of São Paulo)
Alessandra Marra (MCMP/LMU Munich)
Paul McNamara (University of New Hampshire)
Joke Meheus (Ghent University)
Gabriella Pigozzi (Université Paris-Dauphine)
Paul Portner (Georgetown University)
Antonino Rotolo (University of Bologna)
Olivier Roy (Universität Bayreuth)
Leon van der Torre (University of Luxembourg)
Malte Willer (University of Chicago)