In the field of information systems the notion of constraint may be used for quite different kinds of statements. Here we apply deontic logic and doxastic logic to propose formal definitions for the different interpretations of these statements.In our analysis we distinguish practical constraints and deontic constraints; the latter are either obligations about the world or obligations about the correctness of the representation of the world. We also show that to check whether obligations are violated, assumptions (that are also called “constraints") are accepted. These assumptions may also be about the world or about the correctness of its representation. Then, we define what an information system has to know to detect the different kinds of obligation violations. This formal analysis is followed by a pragmatic analysis where we describe the origin of these statements, and in which kinds of processes they are involved.

Keywords: deon00

In this paper we describe how an agent's trust in transactions is a combination of an agent's trust in the other party and the trust in the control mechanisms for the succesful performance of the transaction. This distinction is in particular relevant for the international business-to-business electronic commerce, where trading partners often do not know each other before the trading takes place. We argue also that the agent's understanding of a control mechanism is essential for the agent's trust in that control mechanism. We give a formal analysis of the understanding that is required for control mechanisms to work, and for determining the subjective level of trust in control mechanisms in electronic commerce.

Keywords: deon00

The theory of normative positions attempts to apply a combination of deontic logic and a logic of action/agency to the formalization of the `Hohfeldian concepts' (duty, right, power, privilege, etc.) and other complex normative relations between agents. This paper is concerned with the practical applicability of the theory to such tasks as formalizing the content of an existing set of regulations, designing a new set of regulations, or refining aspects of a computer system specification, with particular attention to the usefulness of the action component as a representational device. Points are made by reference to a simple example concerning rules in a car park. The second part of the paper covers three simple extensions: the representation of `permitted to bring about', a treatment of interpersonal control relations, and the ability to distinguish between being permitted to bring about a new state of affairs and being permitted to sustain a state of affairs that already exists.

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My aim in this paper is to highlight what I view as questionable in Makinson's method of analyzing defeasible conditional obligation sentences, as sketched in "Five faces of minimality". I will focus the discussion on the following two points: the role played by time and the logical properties satsified by the conditional obligation operator.

Keywords: deon00

There is little work of a systematic nature in ethical theory or deontic logic on aretaic notions such as praiseworthiness and blameworthiness, despite their centrality as concepts of common sense morality. Without more work, there is little hope of filling the even larger gap of attempting to develop frameworks integrating such aretaic concepts with deontic concepts of common sense morality, such as what is obligatory, permissible and impermissible. It is also clear in the case of aretaic concepts that agency is central to such appraisal, so some agential notions must be integrated with aretaic concepts as well. The current paper takes the first step in a larger project aimed at the closure of these gaps. Here I sketch a simple framework for the aretaic appraisal of an agent's performance, layered on top of a simple framework for agency, ability, and inevitability, combining elements of work by Brown, Elgesem, Carmo and Santos. In Part II, drawing on work by Chisholm and Sosa on intrinsic preferability, I sketch and explore a framework for defining aretaic superiority, praiseworthiness, blameworthiness, neutrality, and indifference, etc., retaining proper links to agency.

Keywords: deon00

In a range of contexts, one comes across processes resembling inference, but where input propositions are not in general included among outputs, and the operation is not in any way reversible. Examples areise in contexts of conditional obligations, goals, ideals, preferences, actions, and beliefs. In a separate paper, we developed a general theory of such processes when they are applied without restriction. In this paper, we compare systematically several ways of restricting them by consistency constraints.

Keywords: deon00

In a range of contexts, one comes across processes resembling inference, but where input propositions are not in general included among outputs, and the operation is not in any way reversible. Examples areise in contexts of conditional obligations, goals, ideals, preferences, actions, and beliefs. Our purpose is to develop a general theory of propositional input/output operations. Particular attention is given to the special case where outputs may be recycled as inputs.

Keywords: deon00

The paper revisits a class of model structures introduced by the author in 1974, with particular attention to the system SCon, which axiomatizes the universal class. SCon, which independently deserves notics as an algebraically plausible weakest modal system, is self-dual; that is, box and diamond have the same logic. The paper explores the consequences of self-duality for the axiological interpretation of natural frames.

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We follow Makinson's (1999) suggestion to reconstruct deontic logic according to the view that norms are devoid of truth values. Restricting ourselves to unconditional imperatives, we philosophically motivate and defend a logical semantics of imperatives not shaken by Jø rgensen's dilemma, and then show that existing systems can be reconstructed accordingly. So it seems there is a reading according to which deontic logic is after all a logic about, if not of, norms.

Keywords: deon00

In this paper we argue that the distinction between action types and act tokens is relevant for a proper understanding of the distinction between prima facie obligations and all out obligations. After a discussion of the approach in which norms that deal with action types are analysed in terms of the deontic classification of individual acts, we explore the opposite approach. We take norms that deal with action types as primitive, and show how the evaluation of individual acts is influenced (but not determined) bu the deontic status of the several action types which these acts instantiate. This view is formalised, first in a simple version, which disregards exceptions to norms, and then in a more complex variant, which takes exception into account. Finally the distinction between action types and act tokens is used to characterise the distinction between weak and strong permissions.

Keywords: deon00

This multiplex semantics incorporates multiple relations of deontic accessibility or, alternatively, multiple preference rankings, on alternative worlds to represent distinct normative standards. This provides a convenient framework for deontic logic that allows conflicts of obligation, due either to conflicts between normative standards or to incoherence within a single standard. With the multiplex structures, two general senses of 'ought' may be distinguished, an indefinite sense under which something is obligatory when it is enjoined by some normative standard and a core sense for when something is enjoined by all normative standards. Multiple normative standards may themselves be ranked by precedence; this leads to a concept of comparative obligation. This paper presents the foundations of this multiplex semantics and the propositional deontic logic they define.

Keywords: deon00

Keywords: deon00

This paper presents some preliminary work which attempts to adapt, in the context of deontic reasoning, the CO logic defined by Boutilier for reasoning with conditional preferences. The first motivation for this work is that deontic logic can be given a semantics in terms of ordered worlds as in CO logic: the preference relation among worlds aims at ordering words from the most ideal ones to the least ideal ones. The second motivation is that Boutilier introduced a model of an agent's ability by distinguishing between controllable and, influenceable and uninfluenceable propositions. And we noticed that this partition can be related to the notions introduced by Carmo and Jones for reasoning with Contrary-to-Duties. This present work shows an extension of Boutilier's work in order to use CO logic for reasoning with Contrary-to-Duties. The results obtained with this extension do not coincide exactly with those obtained by Carmo and Jones: the full impact of these differences has not yet been studied.

Keywords: deon00

In this paper we address the problem of collective agency, and propose a deontic/action modal logic for that purpose. We argue that once we want to attribute obligations (permissions or other deontic notions) to a set of agents, we need to consider a new agent -an institutionalized agent, and specify how he interacts with the external world: how the obligations flow from the institutionalized agent to the real agents that support him, and how the actions of the latter count as actions of the former. But an agent may act in many qualities (roles), and it is essential to know in which quality an agent has acted, or intends to act, for three main reasons: to know the effects of the act, its deontic qualification, and authentication issues. Thus, we extend the “sees to it" action operator with an explicit index that states the quality (role) in which the agent has acted. We also show how to associate obligations to roles, and illustrate how this can be used to express the desired flow of obligations.

Keywords: deon00

This paper investigates the semantic treatment of conditional obligation, explicit permission (often called positive permission), and prohibition based on models with agents and branched time. In such models branches (rather than moments) are taken as basic, and the branching provides a way to represent the indeterminism which is normally presupposed by talk of free will, responsibility, action and ability. Careful treatment of the relation between ability and responsibility avoids many common problems with accounts of conditional obligation. Recognition of the generality often involved in conditional obligations makes possible a sensitive way of expressing some kinds of general prohibitions, which in turn makes it possible to account for the special role of explicit permission.

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This paper introduces deontic logic of regular actions as a fragment of the modal μ-calculus. Semantic characterizations of deontic notions for regular actions are given in terms of conditions on μ-calculus structures, and μ-calculus formulas capturing this semantics are constructed.

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We consider an infinite hierarchy of systems of Alethic Modal Logic with so called “Levels of Perfection", and add to them suitable definitions of such interesting deontic categories as those of supererogation, offence, conditional obligation and conditional permission. We then state three problems concerning the proper characterization of the resulting logic(s) for our defined notions, and argue for a positive solution to two of these problems.

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Several philosophers and AI researchers have advocated procedure (in the legal sense) as a model of practical reasoning (e.g. Toulmin, Rescher, Loui, Gordon). The idea is that a practical argument is acceptable if it has been successfully defended in a fair and effective procedure for dispute. Yet most work on nonmonotonic logic defines defeasible consequence not in procedural terms but as a declarative relation between premises and conclusion of an argument. In this talk I shall investigate the role of procedure in defeasible legal reasoning. I shall take an idea of Layman Allen seriously that the `nonprovability' referred to in nonmonotonic logic is, when applied to legal reasoning, not logical but legal-procedural nonprovability. I shall present an argument game which leaves room for two legal-procedural phenomena, the introduction of new information and shifts of the burden of proof. I shall argue that these phenomena are essential to the defeasibility of legal reasoning but that they are not captured by current declarative accounts of defeasible reasoning. It remains to be seen to what extent this also holds for other forms of practical reasoning.

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The aim of our paper is to contribute to the formal study of concept formation in normative systems. The framework developed is based on the theory of Boolean algebra, and the basic kind of relations dealt with are called Boolean quasi-orderings. Our framework is abstract in the sense that the main results are not tied to a specific interpretation, although, primarily we have in mind an application where the structure is a normative system and where the Boolean quasi-ordering is a relation of implication between what we call “conditions". The framework is flexible insofar as it can be used either for the joining of two conceptual substructures, called “fragments", within a background structure, or for the generation of a common background structure when two or more particular structures are given. Attention is paid to how equivalent norms can be formulated by different conceptual structures. In particular, we show which structural changes result when norms involving so-called hypothetical normative consequents are reformulated as norms with pure normative consequents.

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In this talk I will start with the problem of Social Order and Social Control (in info-societies and MAS) by illustrating deliberated and spontaneous forms of Social Order and intended or unintended, centralized or decentralized forms of Social Control. I will discuss some approaches to social order in IT and some of its delusions. I will claim that it is possible and necessary to “incorporate" social and normative knowledge and phenomena in intelligent technology, and that in order to effectively support human cooperation -which is strongly based on social, moral, and legal notions- computers must be able to model and “understand" at least partially what happens among the users. They should be able to manage and then partially “understand", for example, permissions, obligations, power, roles, commitments, trust.I will consider here only one facet of the problem of normative social control: the spontaneous and decentralized normative creation, monitoring and intervention. I will not consider the more formal and institutional aspects of social order. In particular, I will discuss some cognitive aspects of the elaboration of spontaneous conventions, implicit commitments, tacit agreements. I will also illustrate our (Conte and Castelfranchi) view of the spontaneous and decentralized issuing and spreading of norms. I will illustrate how I see the transition from “face to face" normative relationships to some stronger constraints of agents' action, and to institutions, authority and law, and how this can increase trust. I will do this by discussing the transition from two parties trust, rights, permission, social commitments, to three parties relationships, where some witness is introduced, or some norm and even some enforcing authority. Finally, in this perspective of formalizing the informal, the interpersonal non-official normative matter, I will consider (also in order to illustrate the danger of a computer-based formalization and enforcement of rules in organizations) the important phenomenon of functional (i.e., collaborative) systematic violation of rules and prescriptions in organization and cooperation; and the emergence -in some cases- of a “convention to violate".

Keywords: deon00

In this paper we introduce a descriptive temporal deontic logic based on causal theories. The underlying nonmonotonic temporal logic has two distinctive properties. First, it distinguishes between observations and interventions, which among others is used to distinguish between the existence and creation of deontic states such as obligations, permissions and prohibitions. Second, its explicit causal theories lead to a descriptive or modeling perspective, that not only enables a simple and intuitive formalization of the benchmark examples of nonmonotonic temporal reasoning, but that also makes the logic a good candidate for applications in computer science.

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