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.
Reasoning with rules and values - Juliano Maranhão
2022 Summer Edition
Although there may be discussion within legal theory about the status of values (morality and public policy) with respect to legal validity, there is a wide acceptance that reasoning with values is an important aspect of the interpretation and application of legal rules. In this lecture, I shall discuss some critical questions regarding the role of values, its dynamic and effect of changing the content and even compromising the validity of positive rules. I shall then present a logical model to represent such dynamic and to cover those critical junctures.
Finding Common Ground for Incoherent Horn Expressions - Marija Slavkovik
2022 Autumn Edition
Autonomous systems that operate in a shared environment with people need to be able to follow the rules of the society they occupy. While laws are unique for one society, different people and institutions may use different rules to guide their conduct. We study the problem of reaching a common ground among possibly incoherent rules of conduct. We formally define a notion of common ground and discuss the main properties of this notion. Then, we identify three sufficient conditions on the class of Horn expressions for which common grounds are guaranteed to exist. We provide a polynomial time algorithm that computes common grounds, under these conditions. We also show that if any of the three conditions is removed then common grounds for the resulting (larger) class may not exist.
Responsibility voids and collective obligations - Hein Duijf
2023 Winter Edition
Societal challenges such as the widespread integration of black-box algorithms and climate change demonstrate that allocating moral responsibility is often difficult or impossible. In complex collective decision processes that involve several stages and multiple decision-makers, it will not always be clear who exactly contributes what and who can be held morally responsible for the final outcome. In the literatures on the ethics of technology and on corporate and group agency, the threat of responsibility voids or gaps is of central importance. A responsibility void obtains if a morally undesirable outcome or decision results from the interaction of several individuals even though none of these individuals can be held responsible for it. In this talk, I will present recent and new research on responsibility voids and collective obligations. The basic underlying framework draws on deontic logic and game and decision theory. The main results indicate that statements about collective obligations cannot be nomologically reduced to any statement in a well-established deontic logic of agency that models every combination of actions, omissions, abilities, and obligations of finitely many individual agents.
Imperatives and the Indirectness of Linguistic Meaning - Cleo Condoravdi
2023 Spring Edition
Imperatives in natural language are used not only to command or prohibit, but also to request, plead, offer, permit, and even to merely express a wish, to give advice on how-to, or to concede. What is common across all these uses? I will propose that imperatives create commitments to preferences. None of the perceived interpretations of imperatives reflect their meaning directly. They all arise from inferences about why the speaker would incur the commitment. This view explains the communicative equivalence of imperatives with necessity modals in some uses, and with possibility modals in others, despite their different underlying semantics. Moreover, it explains an interesting asymmetry between goal-oriented modals and imperatives: while modals can be used to give advice on why a certain goal should be rescinded given the facts of the matter, imperatives cannot.
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