ILLC-LIRa November 2017

illc-lira@list.uva.nl

2 participants
7 discussions

Tomorrow: LIRa session with Anthia Solaki
by LIRa Seminar 29 Nov '17

29 Nov '17

Dear all, Tomorrow we will have our next LIRa session. Speaker: Anthia Solaki (ILLC, Amsterdam) Date and Time: Thursday, November 30th 2017, 16:00-17:30 Venue: KdVI Seminar Room F3.20, Science Park 107. Title: Not so lost in the Wild: logical systems for resource-bounded reasoning. Abstract. Standard epistemic logic is often criticized on the grounds of the problem of logical omniscience: its agents are perfect reasoners with unlimited inferential power. We argue that the appropriate (normative) notion to focus on is that of moderate logical competence and the boundedness of resources is the important feature that determines it. We therefore build a non-standard framework that does justice to both the fallibility and the bounded reasoning of an agent. The former is achieved via the inclusion of impossible worlds to the traditional possible-worlds models. The latter is achieved by imposing suitable connections among the worlds and introducing actions that capture the agent\'s cognitively costly applications of inference rules. More specifically, it is shown that consequences of one\'s knowledge cannot be automatically and effortlessly ascribed to her. However, provided that she can afford to follow the right reasoning path, she can eventually navigate in the Wild and get to know some of them. We also develop non-standard plausibility models to account for the interaction between internal deductive reasoning and the external information the agent receives. A reduction of models to awareness-like structures is devised so that standard modal logic techniques can be exploited to obtain sound and complete axiomatizations. Finally, we discuss connections of these logical systems to dual-process theories of reasoning and give a formal treatment to some of their real-life manifestations. Hope to see you there! The LIRa team

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Thursday LIRa session with Anthia Solaki
by LIRa Seminar 27 Nov '17

27 Nov '17

Dear all, This Thursday we will have our next LIRa session. Speaker: Anthia Solaki (ILLC, Amsterdam) Date and Time: Thursday, November 30th 2017, 16:00-17:30 Venue: KdVI Seminar Room F3.20, Science Park 107. Title: Not so lost in the Wild: logical systems for resource-bounded reasoning. Abstract. Standard epistemic logic is often criticized on the grounds of the problem of logical omniscience: its agents are perfect reasoners with unlimited inferential power. We argue that the appropriate (normative) notion to focus on is that of moderate logical competence and the boundedness of resources is the important feature that determines it. We therefore build a non-standard framework that does justice to both the fallibility and the bounded reasoning of an agent. The former is achieved via the inclusion of impossible worlds to the traditional possible-worlds models. The latter is achieved by imposing suitable connections among the worlds and introducing actions that capture the agent\'s cognitively costly applications of inference rules. More specifically, it is shown that consequences of one\'s knowledge cannot be automatically and effortlessly ascribed to her. However, provided that she can afford to follow the right reasoning path, she can eventually navigate in the Wild and get to know some of them. We also develop non-standard plausibility models to account for the interaction between internal deductive reasoning and the external information the agent receives. A reduction of models to awareness-like structures is devised so that standard modal logic techniques can be exploited to obtain sound and complete axiomatizations. Finally, we discuss connections of these logical systems to dual-process theories of reasoning and give a formal treatment to some of their real-life manifestations. Hope to see you there! The LIRa team

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Tomorrow: LIRa session with Peter Hawke
by LIRa Seminar 22 Nov '17

22 Nov '17

Dear all, Tomorrow we will have our next LIRa seminar. Speaker: Peter Hawke (ILLC, Amsterdam) Date and Time: Thursday, November 23rd 2017, 16:00-17:30 Venue: KdVI Seminar Room F3.20, Science Park 107. Title: Epistemic Logic as Knowability Relative to Information. Abstract. We present a formal semantics for epistemic logic, aimed at capturing the notion of knowability relative to information (KRI). We move from Dretske\'s account of the nature of information, along with his insight that what an agent can know depends on her (empirical) information. We treat operators of the form KAB (‘B is knowable on the basis of information A’) as variably strict quantifiers over worlds with a topic- or aboutness- preservation constraint. Thus, we develop epistemic logic as a conditional logic. Variable strictness models the non-monotonicity of knowledge acquisition while ensuring a more basic sense in which knowledge is stable. Aboutness-preservation models the topic-sensitivity of information, allowing us to invalidate controversial forms of epistemic closure while validating less controversial ones. Thus, unlike the standard modal framework for epistemic logic (i.e. in the style of Hintikka), KRI accommodates various plausible approaches to the Kripke-Harman dogmatism paradox. KRI also strikes a better balance between agent idealization and a non-trivial logic of knowledge ascriptions. In this talk, we focus on foundational motivations, leaving meta-logical results for elsewhere. Hope to see you there! The LIRa team

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LIRa session: Jean Wagemans
by LIRa Seminar 15 Nov '17

15 Nov '17

Dear all, Tomorrow we will have our next LIRa session. Note that this time is in room F3.20 (seminar room in the third floor). Speaker: Jean Wagemans (FGW, University of Amsterdam) Date and Time: Thursday, November 16th 2017, 16:00-17:30 Venue: KdVI Seminar Room F3.20, Science Park 107. Title: Informal sisters of Dame Logica: On the dialectical and rhetorical accounts of argument. Abstract. Inspired by the classical disciplines of dialectic and rhetoric, present-day argumentation theorists have proposed a great variety of classifications of arguments, fallacies, and other means of persuasion. Although these accounts of argument are used for the purpose of producing, analysing, and evaluating argumentative discourse, they are not very satisfactory from a theoretical point of view. Dialectical and rhetorical approaches conceptualize the notion ‘argument’ in a very different way, the descriptions of the types of arguments employ informal language and the classifications are not always based on a clear theoretical rationale. In this talk, Wagemans will present a recently developed framework for integrating the dialectical and rhetorical accounts into a systematic and comprehensive Periodic Table of Arguments. After having given an overview of the main differences between logical, dialectical and rhetorical approaches to argument, he will explain the theoretical framework of the table and illustrate its contents by means of examples. The talk will be concluded with a discussion of the applications of the Periodic Table of Arguments. Hope to see you there! The LIRa team

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Thursday session: Jean Wagemans
by LIRa Seminar 13 Nov '17

13 Nov '17

Dear all, This Thursday we will have our next LIRa session. Speaker: Jean Wagemans (FGW, University of Amsterdam) Date and Time: Thursday, November 16th 2017, 16:00-17:30 Venue: KdVI Seminar Room F3.20, Science Park 107. Title: Informal sisters of Dame Logica: On the dialectical and rhetorical accounts of argument. Abstract. Inspired by the classical disciplines of dialectic and rhetoric, present-day argumentation theorists have proposed a great variety of classifications of arguments, fallacies, and other means of persuasion. Although these accounts of argument are used for the purpose of producing, analysing, and evaluating argumentative discourse, they are not very satisfactory from a theoretical point of view. Dialectical and rhetorical approaches conceptualize the notion ‘argument’ in a very different way, the descriptions of the types of arguments employ informal language and the classifications are not always based on a clear theoretical rationale. In this talk, Wagemans will present a recently developed framework for integrating the dialectical and rhetorical accounts into a systematic and comprehensive Periodic Table of Arguments. After having given an overview of the main differences between logical, dialectical and rhetorical approaches to argument, he will explain the theoretical framework of the table and illustrate its contents by means of examples. The talk will be concluded with a discussion of the applications of the Periodic Table of Arguments. Hope to see you there! The LIRa team

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Tomorrow: LIRa session with 石辰威 Chenwei Shi
by LIRa Seminar 08 Nov '17

08 Nov '17

Dear all, Tomorrow we have our next LIRa session. Speaker: 石辰威 Chenwei Shi (ILLC, Amsterdam) Date and Time: Thursday, November 9th 2017, 16:00-17:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: DeGroot Meets Kripke -- Group belief as a tendency towards consensus. Abstract. In this talk, I propose a notion of group belief -- potential group belief and study its logic. What is group belief? For example, common belief is a notion of group belief, which is studied a lot in epistemic logic. The notion I will talk about is more in line with what is studied in belief merging and judgement aggregation. But our perspective is a little different. Rather than aggregation mechanisms, we put focus on the role of the social network and its influence in the forming of the group\'s collective belief. In this sense, it is more similar to opinion diffusion. This is why we start from the DeGroot model, where the social network and its influence on group members are explicitly characterized. The difficulty is that the DeGroot model deals with degree of belief rather than binary or qualitative belief. Our endeavour thus starts with overcoming this difficulty. After introducing potential group belief, I will show how we can study its logical properties by bringing Kripke semantics into play. Some interesting logical properties emerge, for example, failing to be closed under conjunction. If time permits, I will talk about how to avoid this failure by revising the definition of potential group belief. This is a joint work with Alexandru Baltag, Sonja Smets and Fenrong Liu. Hope to see you there! The LIRa team

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Tomorrow: LIRa session with Yuri David Santos
by LIRa Seminar 01 Nov '17

01 Nov '17

Dear all, Tomorrow we will have our next LIRa session. Speaker: Yuri David Santos (Faculty of Philosophy, University of Groningen) Date and Time: Thursday, November 2nd 2017, 16:00-17:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: A Dynamic Informational-Epistemic Logic. Abstract. Epistemic logic is usually employed to model two aspects of a situation: the ontic and the epistemic aspects. Truth, however, is not always attainable, and in many cases we are forced to reason only with whatever information is available to us. In this work, we will explore a four-valued epistemic logic designed to deal with situations of this sort, where the agents only have knowledge about the available information (not about facts), which can be incomplete or conflicting. The technical results include a set of reduction axioms for public announcements, correspondence proofs, and a complete tableau system. Last, we discuss methods of consolidating this \"knowledge about information\" into factual knowledge/belief. Hope to see you there! The LIRa team

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ILLC-LIRa November 2017