DEON Logo

DEON Seminar Series


2021 is a special year for Deontic Logic. It is the 70th anniversary of the first publication in modern deontic logic: von Wright’s ground breaking and still inspiring article from 1951. It is also the 30th anniversary of the first DEON conference held in Amsterdam in 1991. Today, deontic logic is a fast-growing field whose research agenda covers topics at the interface between computer science, linguistics, philosophy, ethics, the social sciences, and law. Among many other topics, it includes the formal study of normative multi-agent systems, of defeasible normative reasoning, of the semantics and pragmatics of normative expressions in natural language, the formal representation of rights, authorization, delegation, power, and responsibility, and the study of normative aspects of protocols for communication, negotiation and multi- agent decision making. As representatives of the DEON community, we want to take Deontic Logic’s 70th anniversary as as an opportunity to look back at its rich history and draw lessons for the future. As a formal approach to normativity and reasoning, we believe deontic logic can play new roles as a guiding theory in some of the problems in modern AI, philosophy, law and linguistics. To investigate the role of deontic logic in the modern age further, we decided to launch an online seminar series where old ideas are explained, new ideas are explored and modern connections and applications are reflected upon. The seminars are not intended as an alternative to the biannual DEON conferences, but are complementary opportunities to keep in touch with the community and listen in or contribute to presentations and informal discussions on ongoing work. Four times per year (once every season), we will virtually gather to discuss a topic or a paper, or to listen to someone’s new results or opinions. Everyone who is interested in this wonderful area and its questions is welcome.



What is deontic logic for? - Marek Sergot


2021 Autumn Edition (series-opening talk)

This will be a review of issues in the development of deontic logic, understood both narrowly, as the logic of obligation and permission, and more broadly as the formalisation of normative systems. The talk will be based on examples. I want to look at how they might be treated in the light of developments that have taken place over the thirty years since the first of the DEON series was held in Amsterdam in 1991. I considered calling the talk ‘Some things I have said about deontic logic that no-one paid attention to’. However, I will include things that others have said about deontic logic too. Deontic logic is a wide field; I will have to be selective about what issues are covered.



From a two-level perspective on preference to deontic logic - Fenrong Liu


2022 Winter Edition

By 'two-level perspective on preference' I mean the following two aspects: a) given a set of propositions, possibly ordered, we can derive preference relations over individuals. b) Given preference relations between individuals, we can lift them to an ordering over sets of individuals. After introducing the latest studies in these two lines, I will focus on their relevance to deontic logic. In particular, I will illustrate with the lifted Egli-Milner order and its connection to notions of conditional ought and conditional permission.


Norms in action - Emiliano Lorini


2022 Spring Edition

I will provide an introduction to STIT logic, or logic of "seeing to it that", and show how it can be applied to the formalization of a rich variety of legal and social notions including obligations and permissions, social influence and responsibility. I will put special emphasis on the temporal STIT framework, the variant of STIT combining modal operators for agency, representing the consequences of an agent's choice, with temporal operators of linear temporal logic. I will focus on both the axiomatics and complexity aspects of the temporal STIT (T-STIT) framework. Moreover, I will introduce different semantics for T-STIT based on concurrent game structures, interpreted systems and temporal Kripke STIT models. I will present a number of equivalence and non-equivalence results between these semantics relative to the T-STIT language and some of its fragments.



To stay up-do-date with events join our mailinglist.