The Kanger-Lindahl theory of normative positions attempts to use a combination of deontc logic and a logic of action/agency to give a formal account of obligations, duties, rights, and other complex normative concepts. The paper presents a generalization and further development of the Kanger-Lindahl theory, together with methods for its automation and application to practical examples. Particular attention is paid to representations at varying levels of detail, in order that the analysis of examples can be constructed in steps by a process of progressive refinement. The resulting inference methods can be formulated as a simple graph-colouring algorithm, as implemented in the computer program Norman-G.

Keywords: deon98

The aim of this paper is to give formal definitions for fraud situations that can occur in an organized interaction between a number of agents. A distinction between a normative system and its control system is made for specification of these systems. It is argued that a fraud case is one which contains a violation occurring in the normative system and a lie about the fulfilment of that obligation towards the existing control system. The role of deontic logic is discussed for specification of a class of control systems called detective control systems. The fraud definitions given in this paper are given using modal operators in Deontic, Action and Epistemic logic.

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There are already approaches that show how deontic logic can be used in a theory of diagnosis based on minimal sets. In those approaches deontic notions are represented by a propositional language enriched with violation constants. However, diagnoses based on minimal sets are insufficient to capture the specificities of process design diagnosis. In organizational process design it is important to have a preventive diagnosis that, not only detects violations (minimal diagnosis), but also detects cases of unfulfilled obligations. Deontic notions based on violation constants are not adequate if we consider more than minimal diagnosis, mainly because of conditional obligations. In this paper we present an extension of minimal diagnosis theory that addresses process design specificities, and a modal deontic logic that supports this extended theory.

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I recast the DWE-ish deontic framework as an Andersonian-Kangerian modal framework and explore its metatheory systematically and efficiently.

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In this paper we propose the deontic logic DUS, that formalizes reasoning about prescriptive obligations in update semantics. In DUS the definition of logical validity of obligations is not based on truth values but on action dynamics. You know the meaning of a normative sentence if you know the change it brings about in the betterness relation of anyone who is subjected to the news conveyed by it.

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This paper offers arguments in favour of employing normative notions and deontic logic when analysing cryptographic protocols. It also identifies a new class of protocol flaws called violation flaws.

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There are many deontic logical systems in literature. Some deontc logics model universal obligations, others obligations in the current state. An example of the first is Anderson's reduction, an example of the second category is Standard Deontic Logic. A third category is more or less in between, and examples are dyadic deontic lgocis. Also, there is a distinction between ought-to-do and ought-to-be deontic logics. Some ought-to-be deontic logics are mentioned above, whereas an example of ought-to-do is Meyer's reduction. There is a similarity between the universal obligation's of Anderson's ought-to-be reduction and the current obligations in Meyer's ought-to-do reduction. These two deontic logics are the most outlying logics in a variety of deontic logics with obligations which are neither universal, nor local. In this paper the alethinc modality in Anderson's reduction is weakened to a restricted form of necessity and Meyer's reduction is strengthened, applying the same technique. This approach of restricted forms of necessity can be expressed by the so-called release logic. It is a modal logic which is particularly well-fitted for partial specifications, hence, contextual obligations. Finally, both ought-to-be,do reductions will be combined in one single contextual deontic logic.

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The aim of this essay is to tie up some loose ends in deontic logic. Under consideration are two particularly strong deontic systems: Åqvist's dyadic deontic logic G and van Eck's system of temporally relative deontic logic. From van Eck's system of quantificational deontic temporal logic QDTL a corresponding propositional deontic temporal system DTL is constructed to which Arrow's Axiom is added and the resulting system called DTL+. I prove that any “temporally indexed" theorem of G becomes a valid sentence of DTL+ and that any sentence in the language of G which when temporally indexed is valid in DTL+ is valid in G also. Metaphorically speaking, standard dyadic deontic logic as represented by G is the logic of a snap shot taken of any temporal deontic model at any point of time.

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Naturalistic theories of deontic reasoning assume that it is possible to give the truth conditions of deontic sentences by means of solely non-deontic sentences. In this paper it is argued that the fashionable model-theoretic semantics for deontic logic is biased toward the widely shared presupposition that such naturalistic theories are false. A brief argument is given for a naturalistic theory of practical reasoning and it is shown how such a theory can be given a model-theoretic semantics. The argument hinges amongst others on a strict distinction between deontic rules and deontic facts and on the treatment of rules as logical individuals.

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This paper investigates how deontic logic may be combined with relevant logic. Approached in one way deontic principles join easily with relevance. Somewhat surprisingly, approached in another way, which seems a generalization of the first, they combine far less well.

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In this paper, following Scott's advice, we argue that normative reasoning can be represented in a multi-setting framework; in particular in a multi-modal one, where modalities are indexed. Indexed modalities can model several aspects involved in normative reasoning. Systems are combined using Gabbay's fibring methodology which provides complete semantics that can be used to model a labelled tableau like proofs system.

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In this paper we consider the notion of ought-to-do obligation in the context of several concepts of time. Starting from the relatively easy case of discrete time and a lockstep interpretation of actions, we experiment with several plausible definitions and propose a generalized notion of obligation for dense time. A crucial ingredient of the definition proposed is to consider a branching-time temporal operator in order to capture the obligation to a choice of actions adequately.

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It often happens that several different regulations apply to a given organization. And sometimes, these regulations are conflicting, that is, for instance, one regulation says that it is forbidden to do some action while another says it is permitted to do the same action. In this paper, we present a logic, called FUSION, to reason when several regulations are merged together. Our approach is to solve the conflicts by giving an order of priority between the regulations to be merged. We present the axiomatics and semantics of FUSION and prove some “good" properties enforced by this logic.

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This paper investigates a species of multi-agent diachronic deontic logic, based on models with branched time, in which branches, rather than moments are taken as basics. With such models, supplemented by a set of agents, a choice function to model their agency, and an obligation function to induce normative features, we can develop a rich language for describing and analyzing the interrelationships over time between commitments, actions, and abilities.

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In legal theory, it is a well-known idea that an intermediary concept like “ownership" “couples" a set C₁, ..., C_n of legal consequences ti a set F₁, ..., F_p of legal grounds. In our paper we attempt to make the idea of a coupling between grounds and consequences more precise by formulating it as a relation holding between two condition lattices. When stating this, however, it is important to distinguish couplings from mere “connections". -We begin the main exposition by presenting a legal mini-system, where a structure of descriptive conditions is coupled to a structure of normative conditions and where an intermediate concept is used for coupling the two structures. Next, we present a different example where the set of grounds is “open" and we have to deal with a family of coupled structures satisfying a legal requirement. In the following part, we introduce a more rigorous framework for conditions and lattices and develop the formal theory. In particular, we define and explain the notions of connection and coupling, as well as the relations “narrower than" and “wider than" between couplings. Finally, in our conclusion, we suggest that the idea of intermediate concepts can be further developed for elucidating important concepts outside the legal area.

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In this paper we review some aspects of the theory of defeasible conditionals that the late Carlos Alchourrón developed in the last years of his life. These include both philosophical intuitions and formal features of his theory. In particular, we discuss the concept of a contributory condition used by Alchourrón, his formalization of the notion of prima facie duty and the connection between his theory of defeasible conditionals and the AGM logic of theory change.

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The paper argues that we can 'tame' standard deontic logic by narrowing our focus to a particular agent deliberating ar a particular moment. A semantics for obligations and conditional obligations is developed using the Horty/Belnap dstit-semantics together with a preference ordering on the possibilities available to an agent. It is argued that this semantics correctly models reasoning about contrary-to-duty obligations, inclusing a strengthened version of the Chisholm paradox. Defeasible obligations are interpreted as inducing a particular preference ordering, which in turn determines definite obligations for an agent.

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In this paper we present a theorem proving methodology for a restricted but significant fragment of the conditional language made up of (boolean combinations of) conditional statements with unnested antecedents. The method is based on the possible world semantics for conditional logics. The label formalism introduced in [AG94,ABGR96] to account for the semantics of normal modal logics is easily adapted to the semantics of conditional logics by simply indexing labels with formulas. The inference rules are provided by the propositional system KE+ -a tableau-like analytic proof system devised to be used both as a refutation and a direct method proof- enlarged with suitable elimination rules for the conditional connective. The theorem proving methodology we are going to present can be viewed as a first step towards developing appropriate algorithmic framework for several conditional logics for (defeasible) conditional obligation.

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The usual presentations of deontic logic, whether axiomatic or semantic, treat norms as if they could bear truth-values. A fundamental problem of deontic logic, we believe, is to reconstruct it in accord with the philosophical position that norms direct rather than describe, and are neither true nor false. Alchourró n and Bulygin 1981 have indeed made such a construction, refining an earlier one of Stenius 1963, based on the distinction between a norm and a proposition about norms. However it has the limitation that it does not deal with conditional norms. These are covered by an extension of Alchourró n 1993, but with certain shortcomings. Our purpose is to extend the basic 1981 construction in another manner which, we suggest, provides a more satisfactory and sensitive analysis of conditional norms within the same philosophical perspective.The approach takes seriously the warning: no logic of norms without attention to a system of which they form a part. It is based on the notion of the iterative development of output of an explicitly presented normative code, under a given condition. It is neither axiomatic in style nor formulated in terms of a semantics of “possible worlds". It develops output by repeated detachment rather than by consequence (so as not to lose the directionality of conditional norms), and it distinguishes between gross and net output (so as to deal adequately with conditions that are “contrary-to-duty"). The investigation also provides new perspectives on some well known problems. In particular, it throws light on the way in which explicit obligations may have a part in generating permissions, and how explicit permissions may limit obligations. It also helps pin down a distinction between “substantive" and “technical" defeasibility of conditional norms.

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In this paper we introduce and formalize dynamic obligation hierarchies. We begin with a formal definition of obligations. In particular, we require that an agent's obligations are coherent; that is, that each obligation is jointly realisable with all of the obligations which are at least as important. This an agent's obligations form a hierarchy, and new obligations are defined with reference to it. We then show how preferential entailment can be used to formalize the revision of obligations and obligation hierarchies.

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No abstract given.

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No abstract given.

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There are at least three good reasons to try to develop a defeasible version of normative reasoning. First, many norms are prima facie, binding only if they are not overriden by more compelling norms. Second, norms in one system may take precedence over norms in another system, as the principles lex superior and lex posterior require. Third, otherwise attractive principles of normative reasoning often combine to give counterintuitive results unless some method can be developed for repressing some of these principles in troublesome cases.

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