Multiagent Deontic Logic and its Challenges from a Normative Systems Perspective

This article gives an overview of several challenges studied in deontic logic, with an emphasis on challenges involving agents. We start with traditional modal deontic logic using preferences to address the challenge of contrary-toduty reasoning, and STIT theory addressing the challenges of non-deterministic actions, moral luck and procrastination. Then we turn to alternative normbased deontic logics detaching obligations from norms to address the challenge of Jørgensen’s dilemma, including the question how to derive obligations from a normative system when agents cannot assume that other agents comply with their norms. We discuss also some traditional challenges from the viewpoint of normative systems: when a set of norms may be termed ‘coherent’, how to deal with normative conflicts, how to combine normative systems and traditional deontic logic, how various kinds of permission can be accommodated, how meaning postulates and counts-as conditionals can be taken into account,how sets of norms may be revised and merged, and how normative systems can be combined with game theory. The normative systems perspective means that norms, not ideality or preference, should take the central position in deontic semantics, and that a semantics that represents norms explicitly provides a helpful tool for analysing, clarifying and solving the problems of deontic logic. We focus on the challenges rather than trying to give full coverage of related work, for which we refer to the handbook of deontic logic and normative systems

Detachment in Normative Systems: Examples, inference Patterns, Properties

There is a variety of ways to reason with normative systems. This partly reflects a variety of semantics developed for deontic logic, such as traditional semantics based on possible worlds, or alternative semantics based on algebraic methods, explicit norms or techniques from non-monotonic logic. This diversity raises the question how these reasoning methods are related, and which reasoning method should be chosen for a particular application. In this paper we discuss the use of examples, inference patterns, and more abstract properties. First, benchmark examples can be used to compare ways to reason with normative systems. We give an overview of several benchmark examples of normative reasoning and deontic logic: van Fraassen’s paradox, Forrester’s paradox, Prakken and Sergot’s cottage regulations, Jeffrey’s disarmament example, Chisholm’s paradox, Makinson’s Möbius strip, and Horty’s priority examples. Moreover, we distinguish various interpretations that can be given to these benchmark examples, such as consistent interpretations, dilemma interpretations, and violability interpretations. Second, inference patterns can be used to compare different ways to reason with normative systems. Instead of analysing the benchmark examples semantically, as it is usually done, in this paper we use inference patterns to analyse them at a higher level of abstraction. We discuss inference patterns reflecting typical logical properties such as strengthening of the antecedent or weakening of the consequent. Third, more abstract properties can be defined to compare different ways to reason with normative systems. To define these more abstract properties, we first present a formal framework around the notion of detachment. Some of the ten properties we introduce are derived from the inference patterns, but others are more abstract: factual detachment, violation detection, substitution, replacements of equivalents, implication, para-consistency, conjunction, factual monotony, norm monotony, and norm induction. We consider these ten properties as desirable for a reasoning method for normative systems

Hypersequent calculi for non-normal modal and deontic logics: Countermodels and optimal complexity

We present some hypersequent calculi for all systems of the classical cube and their extensions with axioms $T$, $P$, $D$, and, for every $n\geq 1$, rule $RD^+_n$. The calculi are internal as they only employ the language of the logic, plus additional structural connectives. We show that the calculi are complete with respect to the corresponding axiomatisation by a syntactic proof of cut elimination. Then we define a terminating root-first proof search strategy based on the hypersequent calculi and show that it is optimal for coNP-complete logics. Moreover, we obtain that from every saturated leaf of a failed proof it is possible to define a countermodel of the root hypersequent in the bi-neighbourhood semantics, and for regular logics also in the relational semantics. We finish the paper by giving a translation between hypersequent rule applications and derivations in a labelled system for the classical cube

Corpus-Based Research on Chinese Language and Linguistics

This volume collects papers presenting corpus-based research on Chinese language and linguistics, from both a synchronic and a diachronic perspective. The contributions cover different fields of linguistics, including syntax and pragmatics, semantics, morphology and the lexicon, sociolinguistics, and corpus building. There is now considerable emphasis on the reliability of linguistic data: the studies presented here are all grounded in the tenet that corpora, intended as collections of naturally occurring texts produced by a variety of speakers/writers, provide a more robust, statistically significant foundation for linguistic analysis. The volume explores not only the potential of using corpora as tools allowing access to authentic language material, but also the challenges involved in corpus interrogation, analysis, and building

A Stalnakerian Analysis of Metafictive Statements

Because Stalnaker’s common ground framework is focussed on cooperative information exchange, it is challenging to model fictional discourse. To this end, I develop an extension of Stalnaker’s analysis of assertion that adds a temporary workspace to the common ground. I argue that my framework models metafictive discourse better than competing approaches that are based on adding unofficial common grounds