SSLPS

Annual Meeting 2019 - Deontic Logic

The SSLPS Annual Meeting 2019 will be held at the University of Bern on October 24 and 25, 2019. It is organized by Thomas Studer. The meeting is entitled Deontic Logic.

Invited Speakers include

• Federico L.G. Faroldi (Ghent),
• Alessandro Giordani (Milan),
• Piotr Kulicki (Lublin),
• Björn Lellmann (Vienna),
• Xavier Parent (Luxembourg).

Program

Thursday, October 24, 2019

14:00 - 15:00
Alessandro Giordani: Deontic Logic

15:00 16:00
Federico Faroldi: Subtracting Reasons: Open Problems

16:00 - 16:30
Coffee break

16:30 - 17:30
Piotr Kulicki: Towards Deontic Logic for Autonomous Cars

17:30 -18:00
General assembly of the SSLPS


Friday, October 25, 2019

9:30 - 10:30
Björn Lellmann: Proof theory for deontic logic inspired by Indian Philosophy

10:30 - 11:00
Coffee break

11:00 - 12:00
Xavier Parent: Preference-based semantics for dyadic deontic logics in Hansson's tradition: a survey of axiomatisation results

Venue

The meeting takes place at the University of Bern.

Room 220 at Mittelstrasse 43, 3012 Bern

See this map

Abstracts

Federico Faroldi
Subtracting Reasons: Open Problems
Practical reasons can be aggregated to decide what one ought to do. In this talk I explore an operation that undoes aggregation: the subtraction of practical reasons. I distinguish two notions of subtraction: at the level of content and the level of strength. I discuss how to understand precisely the former within the context of justification logic.

Alessandro Giordani
Deontic Logic
One of the basic aims of deontic logicians is to provide systems of logic allowing us to better understand the structure of juridical systems and the way in which important juridical notions are to be conceived. In many contemporary juridical systems a criminal act is characterized by two elements, mens rea and actus reus, and its description appears as the antecedent of conditional norms prescribing a set of legal consequences that compensate for the harm caused by the conduct of the agents. A suitable system of deontic logic should then contain at least three different modules: a first module capturing the notion of mens rea as specified in terms of intentions and knowledge of the fact that an action or lack of action would be or cause an illegal state of affairs; a second module capturing the notion of actus reus as defined in terms of factual responsibility, in turn characterized in terms of causation; a final module capturing the notion of norm and linking this notion to the concepts of legal permission and prohibition. In the present talk I present some contemporary achievements in modal logic, due in particular to dynamic action logic, explicit modal logic, and truthmaker semantics, that can be usefully exploited in order to introduce basic versions of the aforementioned modules.

Piotr Kulicki
Towards Deontic Logic for Autonomous Cars
The presentation will consist of two parts. In the first part I will justify the usefulness of deontic logic for the design and implementation of self-driving vehicles in social environment. Then I will present a simple logical system designed to deal with normative conflicts, including tragic ones, that may occur in the context of autonomous driving. As for the first part I will emphasize the need for clear rules concerning the expected behavior of self driving cars. They are awaited by the prospective car users and other traffic participants, and postulated by many regulative bodies all over the world. Using deontic logic is a convenient way of specifying such rules. Moreover, logic may be used to show the consistency of a system of rules for autonomous vehicles. As an example of the use of logic in such context I will present a system suitable for normative conflicts, that may occur when many factors are considered to asses possible actions. The system is based on preferences on norms and, in case of conflicting norms that are equal in the preference order, a four valued deontic logic.

Björn Lellmann
Proof theory for deontic logic inspired by Indian Philosophy
The syntactic or proof-theoretic approach to the analysis of philsophical concepts such as "obligation" or "prohibition" often encounters a fundamental difficulty. On one side, for the formalisation of basic properties of such concepts it is convenient to use axioms in a Hilbert-style framework. On the other side, for checking that the formalisation is appropriate it is important to know its logical consequences - a task which lends itself to the use of automated reasoning methods. Unfortunately, axiomatic systems are not very suitable as a basis for automated reasoning. Hence there is more and more interest in general methods for the conversion of Hilbert-systems into formal calculi more suitable for automated proof search.
In this talk I will illustrate the power of such methods in the context of deontic logic. More specifically, I will present recent results in the project of formalising principles of deontic reasoning employed by the Mimamsa school of Indian Philosophy. The Mimamsa school reaches back more than 2000 years and constitutes one of the main schools of Indian Philosophy, with a major focus on the explication and analysis of the deontic content of the Indian sacred texts, the Vedas. Interestingly, many principles of deontic reasoning encountered in the Mimamsa texts are shared with the more modern formal approaches, rendering the resulting logics relevant to contemporary deontic logic. A particularly noteworthy feature is a form of non-monotonic reasoning used to resolve conflicts between deontic assumptions via the specificity principle. Apart from the theoretical results I will further present a prototype implementation of the resulting deontic logic.

Xavier Parent
Preference-based semantics for dyadic deontic logics in Hansson's tradition: a survey of axiomatisation results
I present and discuss a number of axiomatization results about so-called dyadic deontic logics in the preference-based semantics tradition. These rely on ranking possible worlds in terms of an Hanssonian binary preference relation of comparative goodness or betterness. In that framework the conditional obligation operator is defined in terms of best antecedent-worlds. The goal is to identify the different systems that can be obtained, depending on the special properties envisaged for the betterness relation, and depending on how the notion of ''best" is understood (optimality vs. maximality, stringent vs. liberal maximization). If time allows, decidability and automated reasoning issues will also be discussed.