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Invited Speakers
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Semantics for more plausible deontic logics
Sven Ove Hansson
Most systems of deontic logic, including standard deontic logic, give rise to blatantly implausible theorems. Attempts to accommodate these "paradoxes" have taken up much of the efforts spent in this field of logic. According to the speaker, in order to avoid the paradoxical results it is necessary to give up the traditional possible world semantics for deontic logic. Instead, we should investigate new semantic constructions on which weaker and more plausible deontic logics can be based. A construction is proposed that is based on the simple idea that whatever is better than something permitted is also permitted. Some results obtained along these lines are presented, including axiomatic characterizations.
Models of Dispute Resolution: a Formal Framework and an Application
Henry Prakken
I will describe a formal framework for models of dispute resolution, and apply it to an example procedure, the Dutch civil summons procedure. A key aim of the framework is to relate (static) logical accounts of defeasible reasoning with (dynamic) models of dispute resolution. The framework is flexible in several respects. It allows for different underlying logics, alternative sets of speech acts and more or less strict rules for when they are allowed. Its formal nature supports the study of formal properties of disputational protocols, especially on how they respect the underlying logic. The example application improves earlier models of legal procedures in several respects. Most importantly, it models a realistic role of the judge, and it models the allocation of the burden of proof as a procedural decision by the judge instead of hardwiring it in the logic or protocol.
New Opportunities in the Formalization of Practical Reasoning
Richmond Thomason
Despite interest in the topic since it was introduced by Aristotle, the practical side of reasoning has remained broadly speculative and informal, at least as a branch of logic. I will argue that ideas from logical AI provide ways of fundamentally improving this situation. I will illustrate the point with examples from my own work, which draws on nonmonotonic logic, planning formalisms, and qualitative theories of preference.
What You Should Probably Know About Deontic Specifications
in a Distributed SettingRon van der Meyden
These are interesting times for those interested in applications of deontic logic, or at least they ought to be. Current research and development in computer science is addressing a host of new types of applications and technologies that have deontic concepts at their core, including digital rights management, web services, personal data services and public key authorization infrastructures. The distributed nature of these applications inherently constrains what implementations are able to achieve. The talk will discuss the new breed of applications and the impact that distributed computing has at the level of deontic specification. In particular, it will be argued that in addition to the deontic modalities, reasoning about knowledge and probability is critical to an understanding of the precise sense in which real distributed systems implement deontic specifications.