In order to provide an implemented language of deontic concepts on complex actions for the purposes of social simulation, we consider the logical representation of obligations, sequences of actions, and the Contrary to Duty (CTD) Paradox. We show that approaches which follow Standard Deontic Logic (Carmo and Jones (2002)) or Dynamic Deontic Logic (Khosla and Maibaum (1987) and Meyer (1988)) encounter problems with obligations, sequences, and CTDs. In particular, it is crucial to differentiate sequences of obligations from obligations on sequences and to consider contract change over time. Contra Meyer (1988), we argue that the CTD problem cannot be reduced to a a sequence of obligations. Contra Carmo and Jones (2002), the analysis of CTDs needs explicit state change and does not need a concept of ideality. We discuss Pörn's Criterion, which states that it is critical to a comprehensive theory of deontic reasoning to take dynamic aspects into account (Pörn (1977:ix-x)); in our view, this ought to encompass Contract State Change. In a theory of deontic specifications on actions, we show that articulated, compositional, and productive markers for violation and fulfillment are key to address the problems identified. The theorical arguments inform the Abstract Contract Calculator, a prototype implementation in Haskell of a language for reasoning with and simulating the results of deontically specified actions (Wyner (2006a) and Wyner (2006b)). With the language, one can represent and study the outcomes of multi-agent artificial normative systems as agents execute actions over time.

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The action language C+ of Giunchiglia, Lee, Lifschitz, McCain, and Turner is a formalism for specifying and reasoning about the effects of actions and the persistence (`inertia') of facts over time. An `action description' in C+ defines a labelled transition system of a certain kind. (formerly known as ) is an extended form of designed for representing normative and institutional aspects of (human or computer) societies. The deontic component of nC+ provides a means of specifying the permitted (acceptable, legal) states of a transition system and its permitted (acceptable, legal) transitions. We present this component of nC+ , motivating its details with reference to some small illustrative examples.

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We solve the problem left open in [5] by providing a complete axiomatisation of deontic interpreted systems on a language that includes full CTL as well as the Ki, Oi and Ki^j modalities. Additionally we show that the logic employed enjoys the finite model property, hence decidability is guaranteed. To achieve these results we follow and extend the technique used by Halpern and Emerson in [2].

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We aim at an adequate formal description of the dynamics of commitments and trust by transferring insights about actual human practices to a formal setting. Our framework is based on Belnap's theory of agents and choices in branching time (stit theory) and his analysis of commitments in terms of strategies. The main points are that (i) commitments come in various degrees of stringency, (ii) we can define a stringency ordering on an agent's possible strategies, and that (iii) trustworthiness can be spelled out in terms of strategies: An agent is living up to a given commitment, and thus, is trustworthy with respect to that commitment, if her strategy is at least as stringent as required. Overall trustworthiness of an agent can be defined by averaging over such single case assessments.

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In legal theory, a well-known idea is that an intermediate concept like “ownership” joins a set of legal consequences to a set of legal grounds. In our paper, we attempt to make the idea of a joining between grounds and consequences more precise by using an algebraic representation of normative systems earlier developed by the authors. In the first main part, the idea of intermediate concepts is presented and earlier discussions of the subjects are outlined. Subsequently, in the second main part, we introduce a more rigorous framework and develop the formal theory. In the third part, the formal framework is applied to examples and some remarks on a methodology of intermediate concepts are given.

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Extending John Horty's multi-agent deontic logic to moral reasoning with subjective utilities, we provide a language and semantics to study moral reasoning with sentences like `Group E of agents ought see to it that phi in the interest of group F'. We illustrate our deontic logic with a new formal analysis of the Prisoner's Dilemma, thereby showing that games can be studied fruitfully with our deontic logic. Finally, we prove a characterization theorem on conflicting obligations.

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In this paper we are interested in non-monotonic extensions of Bengt Hansson's standard dyadic deontic logic 3, known as DSDL3. We study specificity principles for DSDL3 with both controllable and uncontrollable propositions. We introduce an algorithm for minimal specificity which not only covers obligations but also permissions, and we discuss the distinction between weak and strong permissions. Moreover, we introduce ways to combine algorithms for minimal and maximal specificity for DSDL3 with controllable and uncontrollable propositions, based on `optimistic' and `pessimistic' reasoning respectively.

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The paper outlines an approach to the formal representation of signalling conventions, emphasising the prominent role played therein by a particular type of normative modality. It is then argued that, in terms of inferencing related to this modality, a solution can be given to the task J. L. Austin set but failed to resolve: finding a criterion for distinguishing between what Austin called constatives and performatives. The remainder of the paper indicates the importance of the normative modality in understanding a closely related issue: reasoning about trust in communication scenarios; this, in turn, facilitates a clear formal articulation of the role of a Trusted Third Party in trade communication.

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Several systems of monadic deontic logic are defined in terms of systems of alethic modal logic with a propositional constant. When the universal propositional quantifier is added to these systems, the propositional constant becomes definable in terms of the deontic operator. As a result, the meaning of this constant becomes clearer and it becomes easy to axiomatize the deontic fragments of the alethic modal systems.

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This paper studies long-term norms concerning actions. In Meyer's Propositional Deontic Logic (PDeL), only immediate duties can be expressed, however, often one has duties of longer durations such as: “Never do that”, or “Do this someday”. In this paper, we will investigate how to amend PDeL so that such long-term duties can be expressed. This leads to the interesting and suprising consequence that the long-term prohibition and obligation are not interdefinable in our semantics, while there is a duality between these two notions. As a consequence, we have provided a new analysis of the long-term obligation by introducing a new atomic proposition I (indebtedness) to represent the condition that an agent has some unfulfilled obligation.

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This paper studies a logic that combines deontic and temporal aspects. We first present a state/event temporal formalism and define a deontic extension of it. Then, we study the interaction between the temporal dimension and the deontic dimension. We present some logical properties, concerning formulas where deontic and temporal operators are nested, and discuss their intuitive meaning. We focus more particularly on the properties of obligation with deadline and define a specific operator to express this notion.

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A general logical framework is presented to represent speech acts that have institutional effects. It is based on the concepts of the Speech Act Theory and takes the form of the FIPA Agent Communication Language.The most important feature is that the illocutionary force of all of these speech acts is declarative. The formal language that is proposed to represent the propositional content has a large expressive power and therefore allows to represent a large variety of speech acts such as: to empower, to appoint, to order, to declare,...etc. The same formal language is also used to express the feasibility preconditions, the illocutionary effects and the perlocutionary effects.

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In this paper we extend earlier work on deontic deadlines in CTL to the framework of alternating time temporal logic (ATL). The resulting setting enables us to model several concepts discussed in the deontic logic literature. Among the issues discussed are: conditionality, ought implies can, deliberateness, settledness, achievement obligations versus maintenance obligations and deontic detachment. We motivate our framework by arguing for the importance of temporal order obligations, from the standpoint of agent theory as studied in computer science. In particular we will argue that in general achievement obligations cannot do without a deadline condition saying the achievement has to take place before it. Then we define our logic as a reduction to ATL. We demonstrate the applicability of the logic by discussing a possible solution to Chisholm's paradox. The solution differs considerably from other known temporal approaches to the paradox.

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In this paper we reconsider the definition of counts-as relations in normative multiagent systems: counts-as relations do not always provide directly an abstract interpretation of brute facts in terms of institutional facts. We argue that in many cases the inference of institutional facts from brute facts is the result of actions of agents acting on behalf of the normative systems and who are in charge of recognizing which institutional facts follow from brute facts. We call this relation delegation of power: it is composed of a counts-as relation specifying that the effect of an action of an agent is an institutional fact and by a goal of the normative system that the fact is considered as an institutional fact. This relation is more complex than institutional empowerment, where an action of an agent counts-as an action of the normative system but no goal is involved, and than delegation of goals, where a goal is delegated to an agent without giving it any power. With two case studies we show the importance of the delegation of power. Finally, we show how the new definition can be related with existing ones by using different levels of abstraction.

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Logical architectures combine several logics into a more complex logical system. In this paper we study a logical architecture using input/output operations corresponding to the functionality of logical components. We illustrate how the architectural approach can be used to develop a logic of a normative system based on logics of counts-as conditionals, institutional constraints, obligations and permissions. In this example we adapt for counts-as conditionals and institutional constraints a proposal of Jones and Sergot, and for obligations and permissions we adapt the input/output logic framework of Makinson and van der Torre. We use our architecture to study logical relations among counts-as conditionals, institutional constraints, obligations and permissions. We show that in our logical architecture the combined system of counts-as conditionals and insti- tutional constraints reduces to the logic of institutional constraints, which again reduces to an expression in the underlying base logic. Counts-as conditionals and institutional constraints are defined as a pre-processing step for the regulative norms. Permissions are defined as exceptions to obligations and their interaction is characterized.

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In this paper, following the work of Hare, we consider moral reasoning not as the application of moral norms and principles, but as reasoning about what ought to be done in a particular situation, with moral norms perhaps emerging from this reasoning. We model this situated reasoning drawing on our previous work on argumentation schemes, here set in the context of Action-Based Alternating Transition Systems. We distinguish what prudentially ought to be done from what morally ought to be done, consider what legislation might be appropriate and characterise the differences between morally correct, morally praiseworthy and morally excusable actions.

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By making use of modal logic techniques, the paper disentangles two semantically different readings of statements of the type X counts as Y in context C (the classificatory and the constitutive readings) showing that, in fact, "counts-as is said in many ways".

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No abstract given.

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An organization may be the subject of obligations and be responsible for not fulfilling its obligations. And in order for an organization to fulfill its obligations, it must act. But an organization cannot act directly, so someone must act on its behalf (usually some member of the organization), and this must be known by the “external world” (by the agents that interact with the organization). In order to account for this, the organization is usually structured in terms of what we may call posts, or roles within the organization, and the statute of the organization distributes the duties of the organization among the different posts, specifying the norms that apply to those that occupy such positions (that hold such roles), and describing who has the power to act in the name of the organization. But this description is abstract, in the sense that it does not say which particular person can act in the name of the organization; it attributes such power to the holders of some roles. Depending on the type of actions, the power to act in the name of an organization may be distributed through different posts, and the holders of such posts may (or may not) have the permission or the power to delegate such power. On the other hand, those that can act in the name of an organization can establish new obligations for the organization through their acts, for instance by establishing contracts with other agents (persons, organizations, etc.). And in this way we have a dynamic of obligations, where the obligations flow from the organization to the holders of some roles, and these, through their acts, create new obligations in the organization. On the other hand, a person (or, more generally, an agent) can be the holder of different roles within the same organization or in different organizations (being the subject of potentially conflicting obligations), and can act by playing different roles. And in order to know the effects of his acts we must know in which role they were played. Thus, it is fundamental to know which acts count as acts in a particular role. If we want a logical formalism to abstractly specify and reason about all these issues, we need to consider and combine deontic, action and counts-as operators. Particularly critical is to decide which kind of action logic we consider. For some aspects, like that of describing how the obligations flow from the organization to the holders of some posts and how some of the acts of the latter count as acts of the organization, it seems it is better to consider a “static” approach based on the “brings it about” action operators. On the other hand, if we want to be able to describe the dynamics of the obligations deriving, for instance, from the contracts that are made in the name of the organization, it seems that a dynamic logic is necessary, or at least very useful. However, the combination of the two kinds of logic of actions has proven to be not an easy task. This paper addresses these issues.

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Supplementing an account of actions offered by Horty and Belnap [8] makes it more suitable for use in deontic logic. I introduce a new tense operator, for a while in the immediate future, provide for action terms as well as action formulas, and introduce an intention function into our models. With these changes, we are able to (a) explore means/ends relations involving actions, (b) make room for one agent to enable an- other to act, and (c) provide a means for distinguishing intended from unintended consequences. In combination, these improvements make it possible to consider collaborative action aimed at a goal, within a setting open to detailed normative scrutiny of ends, means, actions and intentions.

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Research in logic-based multi-agent modelling has been pushing steadily the boundaries of the domain models adopted, while associated enquiries on the relations between constituent entities contribute in turn to an improved understanding of the underlying domain as well as pave the way for moving beyond static scenarios of analysis (see e.g., Munroe et al. 2003, Boella and van der Torre 2004, Dastani and van der Torre 2005, as well as theoretical work on dynamic semantics in logics). The present talk results from a thread of activities including an ongoing investigation into the relation between the Emotional and computational models of situated normative systems (Staller and Petta 2001, Petta 2003) and work towards the realisation of dynamical representations in multi-agent systems (e.g, Jung and Petta 2005). In it, we will draw a picture of today's status in emotion theorising from the perspective of the ongoing dialogue between computational and psychological research. We will develop a view of the domain of human emotions as informed in particular by cognitive appraisal theories and situated cognition research that illustrates the role of emotions within the coordination of action and (different kinds of ) cognition in social scenarios and tries to clarify the nature of processes and concepts involved.

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