A Decidable Multi-agent Logic for Reasoning About Actions, Instruments, and Norms

We formally introduce a novel, yet ubiquitous, category of norms: norms of instrumentality. Norms of this category describe which actions are obligatory, or prohibited, as instruments for certain purposes. We propose the Logic of Agency and Norms (LAN) that enables reasoning about actions, instrumentality, and normative principles in a multi-agent setting. Leveraging LAN , we formalize norms of instrumentality and compare them to two prevalent norm categories: norms to be and norms to do. Last, we pose principles relating the three categories and evaluate their validity vis-à-vis notions of deliberative acting. On a technical note, the logic will be shown decidable via the finite model property

A functional program for agents, actions, and deontic specifications

Abstract. We outline elements of the Abstract Contract Calculator, a prototype language implemented in Haskell (a declarative programming language) in which we simulate agents executing abstract actions relative to deontic specifications. The deontic specifications are prohibition, permission, and obligation. The concepts of deontic specifications are derived from Standard Deontic Logic and Dynamic Deontic Logic. The concepts of abstract actions are derived from Dynamic Logic. The logics are declarative, while the implementation is operational. In contrast to other implementations, we have articulated and productive violation and fulfillment markers. Our actions are given with explicit action preconditions and postconditions, and we have deontic specification of complex actions. We implement inference in the Contrary-to-Duty Obligations case, which has been a central problem in Deontic Logic. We also distinguish Contrary-to-Duty Obligations from obligations on sequences, which has not previously been accounted for in the literature. The language can be used to express a range of alternative notions of actions and deontic specification. We use it to to model and simulate multi-agent systems in which the behavior of an agent is guided by deontic specifications on actions.

Maintaining Obligations on Stative Expressions in a Deontic Action Logic

Abstract. We consider the logical representation of obligations on stative expressions such as The yard must be clean in the context of legal contract formation, execution, and monitoring (cf. Wyner (2003)). In a contract, the expression may understood as an obligation to maintain a property. We use a Deontic Action Logic to represent obligations over the course of time (Khosla and Maibaum (1987) and Meyer (1988)). Our analysis is in contrast to d’Altan, Meyer, and Wieringa (1996), who reduce deontic operators to an Alethic Logic plus a violation proposition (Anderson and Moore (1957)), which has no temporal component. In addition, they use a Deontic Action Logic to represent obligations on actions. We claim the Alethic component of the logic is redundant for the purposes of representing obligations on stative expressions in a contract. In the course of the analysis, we introduce polynormativity, which contrasts with the binormativity of standard DAL or alethic logic plus a violation proposition. We discuss the advantages of polynormativity in reasoning from violations and fulfillments.