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Leendert Van Der Torre - One of the best experts on this subject based on the ideXlab platform.

  • from classical to non monotonic Deontic Logic using aspic
    International Workshop on Logic Rationality and Interaction, 2019
    Co-Authors: Huimin Dong, Beishui Liao, Reka Markovich, Leendert Van Der Torre
    Abstract:

    In this paper we use formal argumentation to design non-monotonic Deontic Logics, based on two monotonic Deontic Logics. In particular, we use the structured argumentation theory ASPIC\(^+\) to define non-monotonic variants of well-understood modal Logics. We illustrate the approach using argumentation about free-choice permission.

  • a Deontic Logic reasoning infrastructure
    Conference on Computability in Europe, 2018
    Co-Authors: Christoph Benzmuller, Xavier Parent, Leendert Van Der Torre
    Abstract:

    A flexible infrastructure for the automation of Deontic and normative reasoning is presented. Our motivation is the development, study and provision of legal and moral reasoning competencies in future intelligent machines. Since there is no consensus on the “best” Deontic Logic formalisms and since the answer may be application specific, a flexible infrastructure is proposed in which candidate Logic formalisms can be varied, assessed and compared in experimental ethics application studies. Our work thus links the historically rich research areas of classical higher-order Logic, Deontic Logics, normative reasoning and formal ethics.

  • ten problems of Deontic Logic and normative reasoning in computer science
    ESSLLI, 2011
    Co-Authors: Jan Broersen, Leendert Van Der Torre
    Abstract:

    This tutorial presents and discusses ten problems of Deontic Logic and normative reasoning in computer science. Five of the problems have been taken or derived from a list of ten philosophical problems in Deontic Logic recently discussed by Hansen, Pigozzi and van der Torre. In what sense are obligations different from norms? How to reason about contrary-to-duty norms? How do norms change? How to relate various kinds of permissions? What is the role of constitutive norms? Hansen et al. discuss their ten philosophical problems from the viewpoint of input/output Logic as developed by Makinson & van der Torre, and they argue that norms, not ideality, should take the central position in Deontic semantics, and that a semantics for norms explicitly represented in the object language by using, e.g., input/output Logic normative rules, provides a helpful tool for analyzing, clarifying and solving the problems of Deontic Logic. However, for applications in computer science and artificial intelligence we have to reconcile the input-output Logic representation of norms with representations for agency, informational and motivational modalities (beliefs, intentions), time, actions and decision- and game-theoretic concepts. This leads to five more questions. What is the role of time in Deontic reasoning? What is the role of action in Deontic reasoning? How can we use norms to influence, solve, or control games? How do we resolve the general problem of norm compliance? How do norms interact with informational modalities such as beliefs and knowledge, and motivational modalities such as intentions and desires?

  • ten philosophical problems in Deontic Logic
    Dagstuhl Seminar Proceedings, 2007
    Co-Authors: Jorg Hansen, Gabriella Pigozzi, Leendert Van Der Torre
    Abstract:

    The paper discusses ten philosophical problems in Deontic Logic: how to formally represent norms, when a set of norms may be termed 'coherent', how to deal with normative conflicts, how contrary- to-duty obligations can be appropriately modeled, how dyadic Deontic operators may be redefined to relate to sets of norms instead of pref- erence relations between possible worlds, how various concepts of per- mission can be accommodated, how meaning postulates and counts-as conditionals can be taken into account, and how sets of norms may be revised and merged. The problems are discussed from the viewpoint of input/output Logic as developed by van der Torre & Makinson. We ar- gue that norms, not ideality, should take the central position in Deontic semantics, and that a semantics that represents norms, as input/output Logic does, provides helpful tools for analyzing, clarifying and solving the problems of Deontic Logic.

  • Design by contract - Deontic design language forcomponent-based systems
    2003
    Co-Authors: Christophe Garion, Leendert Van Der Torre
    Abstract:

    Design by contract is a well known theory that views software construction as based on contracts between clients (callers) and suppliers (routines), relying on mutual obligations and benefits made explicit by assertions. However, there is a gap between this theory and software engineering concepts and tools. For example, dealing with contract violations is realized by exception handlers, whereas it has been observed in the area of Deontic Logic in computer science that violations and exceptions are distinct concepts that should not be confused. To bridge this gap, we propose a software design language based on temporal Deontic Logic. We also discuss the relation between the normative stance toward systems implicit in the design by contract approach and the intentional or BDI stance popular in agent theory.

Yaohua Tan - One of the best experts on this subject based on the ideXlab platform.

  • contextual Deontic Logic
    Lecture Notes in Computer Science, 1999
    Co-Authors: Leendert Van Der Torre, Yaohua Tan
    Abstract:

    In this article we propose contextual Deontic Logic. Contextual obligations are written as O(α|β\γ), and are to be read as 'α should be the case if β is the case, unless γ is the case'. The unless clause is analogous to the justification in Reiter's default rules. We show how contextual obligations can be used to solve certain aspects of contrary-to-duty paradoxes of dyadic Deontic Logic.

  • prohairetic Deontic Logic pdl
    National Conference on Artificial Intelligence, 1997
    Co-Authors: Leendert Van Der Torre, Yaohua Tan
    Abstract:

    In this paper we introduce Prohairetic Deontic Logic (PDL), a preference-based dyadic Deontic Logic. An obligation 'α should be (done) if β is (done)' is true if (1) no ¬αλβ state is as preferable as an αλβ state and (2) the preferred β states are α states. We show that the different elements of this mixed representation solve different problems of Deontic Logic. The first part of the definition is used to formalize contrary-toduty reasoning, that for example occurs in Chisholm's and Forrester's notorious Deontic paradoxes. The second part is used to make dilemmas inconsistent. PDL shares the intuitive semantics of preference-based Deontic Logics without introducing additional semantic machinery such as bi-ordering semantics or ceteris paribus preferences.

  • the many faces of defeasibility in defeasible Deontic Logic
    1997
    Co-Authors: Leendert Van Der Torre, Yaohua Tan
    Abstract:

    Deontic Logic is the Logic of obligations, i.e. reasoning about what should be the case. Defeasible Logic is the Logic of default assumptions, i.e. reasoning about what normally is the case. In defeasible Deontic Logic these two are combined. An example of this combination is the sentence ‘normally, you should do p’. Now the problem is what to conclude about somebody who does not do p? Is this an exception to the normality claim, or is it a violation of the obligation to do p? This confusion arises because there is a substantial overlap between Deontic and defeasibility aspects. In this article we analyze this overlap, and we also show that this confusion can be avoided if one makes the proper distinctions between different types of defeasibility. Furthermore, we also show that these distinctions are essential for an adequate analysis of notorious contrary-to-duty paradoxes such as the Chisholm and Forrester paradoxes.

  • how to combine ordering and minimizing in a Deontic Logic based on preferences
    DEON, 1996
    Co-Authors: Yaohua Tan, Leendert Van Der Torre
    Abstract:

    In this paper we propose a semantics for dyadic Deontic Logic with an explicit preference ordering between worlds, representing different degrees of ideality. We argue that this ideality ordering can be used in two ways to evaluate formulas, which we call ordering and minimizing. Ordering uses all preference relations between relevant worlds, whereas minimizing uses the most preferred worlds only. We show that ordering corresponds to strengthening of the antecedent, and minimizing to weakening of the consequent. Moreover, we show that in some cases ordering and minimizing have to be combined to obtain certain desirable conclusions, and that this can only be done in a so-called two-phase Deontic Logic. In the first phase, the preference ordering is constructed, and in the second phase the ordering is used for minimization. If these two phases are not distinguished, then counterintuitive conclusions follow.

Xavier Parent - One of the best experts on this subject based on the ideXlab platform.

  • a Deontic Logic reasoning infrastructure
    Conference on Computability in Europe, 2018
    Co-Authors: Christoph Benzmuller, Xavier Parent, Leendert Van Der Torre
    Abstract:

    A flexible infrastructure for the automation of Deontic and normative reasoning is presented. Our motivation is the development, study and provision of legal and moral reasoning competencies in future intelligent machines. Since there is no consensus on the “best” Deontic Logic formalisms and since the answer may be application specific, a flexible infrastructure is proposed in which candidate Logic formalisms can be varied, assessed and compared in experimental ethics application studies. Our work thus links the historically rich research areas of classical higher-order Logic, Deontic Logics, normative reasoning and formal ethics.

  • faithful semantical embedding of a dyadic Deontic Logic in hol
    arXiv: Artificial Intelligence, 2018
    Co-Authors: Christoph Benzmuller, Ali Farjami, Xavier Parent
    Abstract:

    A shallow semantical embedding of a dyadic Deontic Logic by Carmo and Jones in classical higher-order Logic is presented. This embedding is proven sound and complete, that is, faithful. The work presented here provides the theoretical foundation for the implementation and automation of dyadic Deontic Logic within off-the-shelf higher-order theorem provers and proof assistants.

  • Maximality vs. Optimality in Dyadic Deontic Logic
    Journal of Philosophical Logic, 2014
    Co-Authors: Xavier Parent
    Abstract:

    This paper reports completeness results for dyadic Deontic Logics in the tradition of Hansson’s systems. There are two ways to understand the core notion of best antecedent-worlds, which underpins such systems. One is in terms of maximality, and the other in terms of optimality. Depending on the choice being made, one gets different evaluation rules for the Deontic modalities, but also different versions of the so-called limit assumption. Four of them are disentangled, and compared. The main observation of this paper is that, even in the partial order case, the contrast between maximality and optimality is not as significant as one could expect, because the Logic remains the same whatever notion of best is used. This is established by showing that, given analogous properties for the betterness relation, the same system is sound and complete with respect to its intended modelling. The chief result of this paper concerns Åqvist’s system F supplemented with the principle ( CM ) of cautious monotony. It is established that, under the maximality rule, F  + (CM) is sound and complete with respect to the class of models in which the betterness relation is required be reflexive and smooth (for maximality). From this, a number of spin-off results are obtained. First and foremost, it is shown that a similar determination result holds for optimality; that is, under the optimality rule, F  + (CM) is also sound and complete with respect to the class of models in which the betterness relation is reflexive and smooth (for optimality). Other spin-off results concern classes of models in which further constraints are placed on the betterness relation, like totalness and transitivity.

  • two dimensional standard Deontic Logic including a detailed analysis of the 1985 jones porn Deontic Logic system
    Synthese, 2012
    Co-Authors: Mathijs De Boer, Dov M. Gabbay, Xavier Parent, Marija Slavkovic
    Abstract:

    This paper offers a two dimensional variation of Standard Deontic Logic SDL, which we call 2SDL. Using 2SDL we can show that we can overcome many of the difficulties that SDL has in representing linguistic sets of Contrary-to-Duties (known as paradoxes) including the Chisholm, Ross, Good Samaritan and Forrester paradoxes. We note that many dimensional Logics have been around since 1947, and so 2SDL could have been presented already in the 1970s. Better late than never! As a detailed case study illustrating the power of 2SDL, we examine the system DL of Deontic Logic of Andrew Jones and Ingmar Porn offered in 1985 to solve the Chisholm paradox of Contrary to Duties. The critical examination is done using Logics and methods available in 1985 and solutions are proposed using what was available in 1985.

  • Moral particularism in the light of Deontic Logic
    Artificial Intelligence and Law, 2011
    Co-Authors: Xavier Parent
    Abstract:

    The aim of this paper is to strengthen the point made by Horty about the relationship between reason holism and moral particularism. In the literature prima facie obligations have been considered as the only source of reason holism. I strengthen Horty’s point in two ways. First, I show that contrary-to-duties provide another independent support for reason holism. Next I outline a formal theory that is able to capture these two sources of holism. While in simple settings the proposed account coincides with Horty’s one, this is not true in more complicated or “realistic” settings in which more than two norms collide. My chosen formalism is so-called input/output Logic. A bottom-line example is introduced. It raises the issue of whether the conventional wisdom is right in assuming that normative reasons run parallel to epistemic ones.

Guido Governatori - One of the best experts on this subject based on the ideXlab platform.

  • a defeasible Deontic Logic for pragmatic oddity
    Social Science Research Network, 2020
    Co-Authors: Guido Governatori, Silvano Colombo Tosatto, Antonino Rotolo
    Abstract:

    We introduce a variant of Deontic Defeasible Logic to handle the issue of Pragmatic Oddity. The key idea is that a conjunctive obligation is allowed only when each individual obligation is independent from the violation of the other obligations. The solution makes essential use of the constructive proof theory of the Logic while maintaining a feasible computational complexity.

  • free choice permission in defeasible Deontic Logic
    International Conference on Legal Knowledge and Information Systems, 2020
    Co-Authors: Guido Governatori, Antonino Rotolo
    Abstract:

    Free Choice Permission is one of the challenges for the formalisation of norms. In this paper, we follow a novel approach that accepts Free Choice Permission in a restricted form. The intuition behind the guarded form is strongly aligned with the idea of defeasibility. Accordingly, we investigate how to model the guarded form in Defeasible Deontic Logic extended with disjunctive permissions.

  • traffic rules encoding using defeasible Deontic Logic
    International Conference on Legal Knowledge and Information Systems, 2020
    Co-Authors: Hanif Bhuiyan, Guido Governatori, Andy Bond, Sebastien Demmel, Mohammad Badiul Islam, Andry Rakotonirainy
    Abstract:

    Automatically assessing driving behaviour against traffic rules is a challenging task for improving the safety of Automated Vehicles (AVs). There are no AV specific traffic rules against which AV behaviour can be assessed. Moreover current traffic rules can be imprecisely expressed and are sometimes conflicting making it hard to validate AV driving behaviour. Therefore, in this paper, we propose a Defeasible Deontic Logic (DDL) based driving behaviour assessment methodology for AVs. DDL is used to effectively handle rule exceptions and resolve conflicts in rule norms. A data-driven experiment is conducted to prove the effectiveness of the proposed methodology.

  • is free choice permission admissible in classical Deontic Logic
    arXiv: Logic in Computer Science, 2019
    Co-Authors: Guido Governatori, Antonino Rotolo
    Abstract:

    In this paper, we explore how, and if, free choice permission (FCP) can be accepted when we consider Deontic conflicts between certain types of permissions and obligations. As is well known, FCP can license, under some minimal conditions, the derivation of an indefinite number of permissions. We discuss this and other drawbacks and present six Hilbert-style classical Deontic systems admitting a guarded version of FCP. The systems that we present are not too weak from the inferential viewpoint, as far as permission is concerned, and do not commit to weakening any specific Logic for obligations.

  • practical normative reasoning with defeasible Deontic Logic
    Reasoning Web International Summer School, 2018
    Co-Authors: Guido Governatori
    Abstract:

    We discuss some essential issues for the formal representation of norms to implement normative reasoning, and we show how to capture those requirements in a computationally oriented formalism, Defeasible Deontic Logic, and we provide the description of this Logic, and we illustrate its use to model and reasoning with norms with the help of legal examples.

Daniel Rönnedal - One of the best experts on this subject based on the ideXlab platform.

  • DYADIC Deontic Logic
    2016
    Co-Authors: Daniel Rönnedal
    Abstract:

    Abstract. The purpose of this paper is to develop a class of semantic tableau systems for some dyadic Deontic Logics. We will consider 16 different pure dyadic Deontic tableau systems and 32 different alethic dyadic Deontic tableau systems. Possible world semantics is used to interpret our formal languages. Some relationships between our systems and well known dyadic Deontic Logics in the literature are pointed out and soundness results are obtained for every tableau system. Completeness results are obtained for all 16 pure dyadic Deontic systems and for 16 alethic dyadic Deontic systems

  • quantified temporal alethic Deontic Logic
    Logic and Logical Philosophy, 2014
    Co-Authors: Daniel Rönnedal
    Abstract:

    The purpose of this paper is to describe a set of quantified temporal alethic-Deontic systems, i.e., systems that combine temporal alethicDeontic Logic with predicate Logic. We consider three basic kinds of systems: constant, variable and constant and variable domain systems. These systems can be augmented by either necessary or contingent identity, and every system that includes identity can be combined with descriptors. All Logics are described both semantically and proof theoretically. We use a kind of possible world semantics, inspired by the so-called T × W semantics, to characterize them semantically and semantic tableaux to characterize them proof theoretically. We also show that all systems are sound and complete with respect to their semantics.

  • temporal alethic Deontic Logic and semantic tableaux
    Journal of Applied Logic, 2012
    Co-Authors: Daniel Rönnedal
    Abstract:

    The purpose of this paper is to describe a set of temporal alethic–Deontic systems, i.e. systems that include temporal, alethic and Deontic operators. All in all we will consider 2,147,483,648 syst ...

  • extensions of Deontic Logic an investigation into some multi modal systems
    2012
    Co-Authors: Daniel Rönnedal
    Abstract:

    Deontic Logic is a branch of Logic that deals with normative concepts, propositions, arguments and systems. The main purpose of this compilation thesis is to investigate how Deontic Logic can be ex ...