Date and time: Monday, 23 August,  16:00-17:30

Location: Room 353, Xinzhai Building

Speaker: Prof. Sven Ove Hansson (Department of Philosophy and the History of Technology, Royal Institute of Technology, Sweden.)

Title: Cognitive realism in belief revision: Representing a finite mind

Abstract:  Since a human mind cannot deal directly with infinite structures, cognitively realistic models of belief change should operate on belief states that have a finite representation. The standard AGM model cannot easily be reconciled with that requirement. Different ways to achieve a finite representation are discussed, in particular: finite language, belief bases, and specified meet contraction. Formal results that compare and connect the different approaches are presented.

Theoretical Aspects of Rationality and Knowledge (TARK XIII) Conference
                    Groningen, the Netherlands, 11-15 July 2011

                             First Announcement

* Scope and Mission

The mission of the TARK conferences is to bring together researchers from a wide variety of fields, including Artificial Intelligence, Cryptography, Distributed Computing, Economics and Game Theory, Linguistics, Philosophy, and Psychology, in order to further our understanding of interdisciplinary issues involving reasoning about rationality and knowledge.

Topics of interest include, but are not limited to, semantic models for knowledge, belief, and uncertainty, bounded rationality and resource-bounded reasoning, commonsense epistemic reasoning, epistemic logic, knowledge and action, applications of reasoning about knowledge and other mental states, belief revision, and foundations of multi-agent systems.

* Workshops
Two full-day workshops will precede and follow the conference: “Reasoning about other minds: logical and cognitive perspectives”,“Quantum physics meets TARK”.

* Important Dates
Submission of Abstracts: March 10th, 2011
Notification of Authors: April 29th, 2011
Camera Ready Copy of Accepted Papers due: May 20th, 2011
Conference Dates: 11-15 July 2011

* Programme Committee：
Natasha Alechina, University of Nottingham
Krzysztof R. Apt (PC chair), CWI and University of Amsterdam
Sergei Artemov, CUNY, New York
Hans van Ditmarsch, University of Sevilla
Aviad Heifetz, The Open University of Israel
Wiebe van der Hoek, University of Liverpool
Daniel Lehmann, The Hebrew University of Jerusalem
Jerome Lang, Universite Paris-Dauphine
Fenrong Liu, Tsinghua University, Beijing
Alessio Lomuscio, Imperial College London
Ron van der Meyden, University of New South Wales, Sydney
Eric Pacuit (tutorials chair), Tilburg University
Andres Perea, Maastricht University
Gabriella Pigozzi, University of Luxembourg
R. Ramanujam, Institute of Mathematical Sciences, Chennai
Sonja Smets, University of Groningen
Moshe Tennenholtz, Technion, Haifa and Microsoft, Herzliya
Rineke Verbrugge, University of Groningen

* Local Organization：
Sonja Smets
Rineke Verbrugge

Date and time: Wednesday, 23 June, 5.30-7pm
Location: T206 (Lakatos Building, Second Floor)
Speaker: Brian Hill (HEC Paris) 
Title: Beyond Probabilities: Belief, Confidence and Decision-Making
 
Abstract:  The standard representation of beliefs in decision theory and much of formal epistemology, by probability measures, is incapable of representing an agent’s confidence in his beliefs. However, as shall be argued in this talk, the agent’s confidence in his beliefs plays, and should play, an central role in many of the most difficult decisions which we find ourselves faced with – and indeed, in several sorts of decisions which have been largely ignored in the Bayesian literature. The aim of this talk is to formulate a representation of agents’ doxastic states and a (axiomatically grounded) theory of decision which recognises and incorporates confidence in belief. Time-permitting, attitudes to choosing in the absence of confidence, applications and further directions will be discussed.

Date and Time: 19 June, 2010 , 9:00-12:00

Location: Room 335,  Xinzhai Building at Tsinghua University

Lecture 1: Shichang Song(University of Illinois at Urbana-Champaign)            Title: Continuous Logic and Probability                                                              Abstract: Continuous first-order logic is an analog of classical first-order logic. Unlike classical logic with the truth value {True, False}, continuous logic ‘s truth value is the whole interval [0,1]. Continuous model theory also preserves many key properties of classical model theory. Although continuous first-order logic was introduced quite recently, it has already been applied to analysis and probability theory. During this talk, I will introduce continuous logic briefly and then discuss the applications to probability theory. If time permits, I’ll also show some of my recent results in this topic.

Lecture 2: Dick de Jongh (University of Amsterdam)                                          Title: Comparing Strengths of Beliefs explicitly                                           Abstract: Inspired by a similar use in provability logic, formulas p >_B q and ≥_B q are introduced in the existing logical framework for discussing beliefs to express that the strength of belief in p is greater than (or equal to) that in q. This explicit mention of the comparison in the logical language aids in defining several other concepts in a uniform way, viz. older and rather clear concepts like the operators for universality (which possibilities ought to be considered), together with newer notions like plausibility (in the sense of ‘more plausible than not’) and disbelief. Moreover, it assists in studying the properties of the concept of greater strength of belief itself. A heavy part is played in our investigations by the relationship between the standard plausibility ordering of the worlds and the strength of belief ordering. If we try to define the strength of belief ordering in terms of the world plausibility ordering we get some undesirable consequences, so we have decided to keep the relation between the two orderings as light as possible to construct a system that allows for widely different interpretations. Finally, after a brief discussion on the multi-agent setting, we move on to talk about the dynamics – the change of ordering under the influence of hard and soft information.

LSE Choice Group Talk this week:
 
Katie Steele (LSE)
Testimony as Evidence
 
Wednesday, 16 June, 5.30-7pm
LSE, Lakatos Building, T206 (Second Floor)
 
Abstract.  This paper concerns how beliefs should be updated in response to a special kind of evidence—the testimony of others. That is, when an agent learns the beliefs of others on some issue, how should this affect their own beliefs on that issue? Averaging models (linear/geometric) for updating on testimony are popular in both mainstream and formal epistemology circles, but a large question mark remains vis-à-vis the normative acceptability of these models. Here we investigate the relationship between averaging models and the Bayesian model for updating on testimony, the latter being taken as the normative standard. Some criticisms of averaging can be avoided by positioning it as an extra-Bayesian process: a method for deciding new probabilities across some partition, to be followed by Jeffrey conditioning. Ultimately, however, averaging methods for updating on testimony are seriously undermined by Wagner’s (2002) general characterization of evidence, and how it should impact on belief.

LogKCA 2010

http://www.ilcli.ehu.es/p287content/en/contenidos/evento/logkca10_call_for_papers/en_logkca10/logkca10_callpapers.html

Time: 3-5 November 2010

Location: Donostia, San Sebastian (Spain)

This Workshop seeks to examine and explore issues concerning the logical and philosophical aspects of knowledge, communication and action in an integrated view. Perspectives are sought from those engaged in the fields of logic, history and philosophy of logic, logic applied to artificial intelligence and cognitive systems, general epistemology, social epistemology, belief theory, communication theory, discourse theory, formal semantics, pragmatics, philosophy of action, and history of philosophy connected with those topics. These disciplines are indicative only as papers are welcomed from any area, in which logic and philosophy of KCA play a part.

LECTURES
Sergei ARTEMOV (City University of New York)
Arnon AVRON (School of Computer Science, Tel Aviv University)
Carlos MOYA (University of Valencia)
Jaroslav PEREGRIN (University of Hradec Králové, Czech Republic)

TUTORIALS
Alexandru BALTAG (Computing Laboratory, Oxford University)
Patrick BLACKBURN (CNRS-Loria, France)
Eric PACUIT (Center for Logic and Philosophy of Science, Tilburg Univ.)
John SYMONS (University of Texas, El Paso)

Contributed papers
Contributed papers (25-30 minutes) may be presented on any of the following themes:
Applied logics of knowledge, knowledge acquisition and transmission, knowledge in a social setting.
Logics of belief, belief formation and justification, belief update and revision, rationality problems.
Philosophy of information.
Logics of communication.
Non-classical logics applied to information and cognition.
Philosophy of communication.
Formal epistemology.
General logics of action, dynamic logic, logic of intentions and goals, game-theoretical frames.
Logics for social action, collective action, and cooperative action.
Probability logics, non-monotonic logics, and hybrid logics connected to KCA.
The history of logics of KCA.

Authors wishing to submit a paper should send by JUNE 25, 2010, a 4-page  (2000- 2500 words) abstract, with no more than five keywords, and including separately notes and references at the end, by e-mail to the Secretary of the Program Committee (josebaxabier.arrazola@ehu.es). If selected for presentation, 15-20 pages papers should be submitted by September 4, 2010. Papers will be blind peer reviewed, by the Program Committee. The Proceedings with the lectures, tutorials and contributed papers will be published by The University of the Basque Country Press, before the beginning of the Workshop.

IMPORTANT DATES
June 25, 2010 Deadline for Contributed Papers.
July 9, 2010 Notification of acceptance/rejection.
If selected for presentation: September 4, 2010 Deadline for Papers. (15-20 pages papers)

Registration
The Registration fee (including Proceedings) is 120 euro (70 euro for students)before October 4, 2010.

Further information
Dr. Xabier Arrazola
Secretary of the Program Committee  josebaxabier.arrazola@ehu.es
Dr. Mara Ponte
Secretary of the Organizing Committee maria.deponte@ehu.es

Program Committee
X. Arrazola (Donostia, Secretary), R. Bosch (Oviedo), M. Colombetti (Trier), J. Ezquerro (Donostia), J.M. Larrazabal (Donostia), J.Martínez (Barcelona), E. Rast (Lisboa), J. Salto (Leon), S. Sequoiah-Grayson (Oxford), M. Vazquez (La Laguna)

Organizing Committee
E. Alonso (London), E. Casaban (Valencia), E. Ezenarro (Donostia), L. A.
Prez Miranda (Donostia), M. Ponte (Donostia, Secretary), M. Sebastian(Barcelona), R. Trypuz (Lublin), A. Ulazia (Eibar)

EVENT: GroLog Lecture
SPEAKER: Rohit Parikh (City University of New York)
DATE: Thursday 10 June, 2010
TIME: 15:15 — 17:00
PLACE: Room 5161.0165 in the Bernoulliborg Building on the  Zernikecomplex, Nijenborgh 9

TITLE: Measuring Belief
ABSTRACT:
Knowledge is understood as justified true belief, plus something else, as we all know from Gettier. But if belief is an important component of knowledge, then in order to understand knowledge, we need to think more about belief.

Actual beliefs are not closed under logical inference, and they can be inconsistent with each other. Moreover, expressed belief may conflict with observed behavior. All of this was pointed out by Daniel Kahneman in his Nobel lecture. So we need something more refined than Kripke structures to deal with actual belief.

We point out that beliefs can be observed in two ways. One is by simply asking the agent and presuming that one is told the truth. The other way is to observe the choices made by an agent and inferring from these observations both the beliefs and the preferences of the agent.

This second way was pursued, among others, by Ramsey and Savage, and is, indeed the only way we have of assigning beliefs to infants and animals. But we still retain the “vanilla” notion of belief, namely beliefs ascertained by asking questions. Adults of course have both notions of belief and they are often, but not always, correlated with each other.

We will discuss these two ways of understanding belief, compare them to Tamar Gendler’s notion of “alief”, and also mention the experimental work of Verbrugge and her colleagues.

Time: 3-5 November 2010

Location: Donostia – San Sebastián (Spain)
This Workshop seeks to examine and explore issues concerning the logical and philosophical aspects of knowledge, communication and action in an integrated view. Perspectives are sought from those engaged in the fields of logic, history and philosophy of logic, logic applied to artificial intelligence and cognitive systems, general epistemology, social epistemology, belief theory, communication theory, discourse theory, formal semantics, pragmatics, philosophy of action, and history of philosophy connected with those topics. These disciplines are indicative only as papers are welcomed from any area, in which logic and philosophy of KCA play a part.

LECTURES
Sergei ARTEMOV                (City University of New York)
Arnon AVRON           (School of Computer Science, Tel Aviv University)
Carlos MOYA           (University of Valencia)
Jaroslav PEREGRIN     (University of Hradec Králové, Czech Republic)

TUTORIALS
Alexandru BALTAG      (Computing Laboratory, Oxford University)
Patrick BLACKBURN     (CNRS-Loria, France)
Eric PACUIT           (Center for Logic and Philosophy of Science, Tilburg Univ.)
John SYMONS           (University of Texas, El Paso)
Contributed papers
Contributed papers (25-30 minutes) may be presented on any of the following themes:
 •Applied logics of knowledge, knowledge acquisition and transmission,  knowledge in a social setting.
•Logics of belief, belief formation and justification, belief update and revision, rationality problems.
•Philosophy of information.
•Logics of communication.
•Non-classical logics applied to information and cognition.
•Philosophy of communication.
•Formal epistemology.
•General logics of action, dynamic logic, logic of intentions and goals, game-theoretical frames.
•Logics for social action, collective action, and cooperative action.
•Probability logics, non-monotonic logics, and hybrid logics connected to KCA.
•The history of logics of KCA.

Authors wishing to submit a paper should send by JUNE 25, 2010, a 4-page (2000- 2500 words) abstract, with no more than five keywords, and including separately notes and references at the end, by e-mail to the Secretary of the Program Committee (josebaxabier.arrazola@ehu.es). If selected for presentation, 15-20 pages papers should be submitted by September 4, 2010. Papers will be blind peer reviewed, by the Program Committee. The Proceedings with the lectures, tutorials and contributed papers will be published by The University of the Basque Country Press, before the beginning of the Workshop.

IMPORTANT DATES
June 25, 2010 Deadline for Contributed Papers.
July 9, 2010 Notification of acceptance/rejection.
If selected for presentation: September 4, 2010 Deadline for Papers. (15-20 pages papers)

 Registration
The Registration fee (including Proceedings) is 120 euro (70 euro for students)before October 4, 2010.

Further information
Dr. Xabier Arrazola
Secretary of the Program Committee josebaxabier.arrazola@ehu.es
Dr. María Ponte
 Secretary of the Organizing Committee maria.deponte@ehu.es

Program Committee
X. Arrazola (Donostia, Secretary), R. Bosch (Oviedo), M. Colombetti (Trier),
J. Ezquerro (Donostia), J.M. Larrazabal (Donostia), J.Martínez (Barcelona),
E. Rast (Lisboa), J. Salto (Leon), S. Sequoiah-Grayson (Oxford),
M. Vazquez (La Laguna)

Organizing Committee
E. Alonso (London), E. Casaban (Valencia), E. Ezenarro (Donostia), L. A.
Pérez Miranda (Donostia), M. Ponte (Donostia, Secretary), M. Sebastian
(Barcelona), R. Trypuz (Lublin), A. Ulazia (Eibar)

Messages to the list are archived at
http://listserv.liv.ac.uk/archives/philos-l.html.
Prolonged discussions should be moved to chora: enrol via
http://listserv.liv.ac.uk/archives/chora.html.
Other philosophical resources on the Web can be found at http://www.liv.ac.uk/pal.

TITLE : Rational choice and belief formation – problems and projects

SPEAKER : prof. Hans Rott

Tuesday 18 May 2010, 15:15 – 17:00 h
Faculty of Philosophy, Oude Boteringestraat 52, room Beta

In this talk I first survey how rational choice theory can be applied to
processes of belief formation and transformation. A wide-ranging
correspondence between independently motivated postulates suggests
that  the theoretical problem of fixing one’s beliefs in a rational way is
reducible to the (wider) practical problem of selecting optimal
solutions in choice situations. However, this interpretation faces
several problems. One of them concerns the psychological reality of
acts  of free choice that are assumed to be involved in such processes. Then
I discuss a number of apparent anomalies of rational choice theory.
Three classes of scenarios are considered that have been the subject of a
vivid discussion in the context of probabilistic choice since the 1960s
(by Debreu, Tversky and others). They are recast in a non-probabilistic
setting, and it is shown how they can at the same time be regarded as
logical problems that concern the drawing of defeasible inferences
from a given information base. I argue that these apparent anomalies do not
present genuine instances of human irrationality, and close by listing
a  number of open questions.

Hans Rott has been a professor of philosophy at the University of
Regensburg since 1999. Before that, he was an assistant professor at
the University of Konstanz (1990-1997) and a professor at the University
of Amsterdam (1997-1999). He obtained a PhD from the University of Munich
(1991) and a Habilitation from the University of Konstanz (1997), the
theses being about belief revision and nonmonotonic reasoning, with
connections to the philosophy of science and economics. Recent and
current research concerns the logical modelling of theoretical and
practical forms of rationality, belief formation and conditionals, the
notions of disagreement and misunderstanding, and assorted topics in
the philosophy of the enlightenment. He has been editor-in-chief of
Erkenntnis since 2001 and a vice-president of the German Society for
Analytic Philosophy (GAP) since 2003.

On Wednesday the 14th of April, the City University of New York continues their Logica and Games seminar, this time with a double session with Alexandru Baltag and Eric Pacuit.

Dr. Alexandru Baltag (Oxford University): Truth-tracking by belief revision

Abstract.
This is joint work with Nina Gierasimczuk and Sonja Smets. I present some new results at the intersection of Belief Revision and Learning Theory, and I reflect on the epistemological significance of these and other older learning-theoretic results. The learning agent’s initial epistemic state S is given by a set of possible worlds (identified with valuations over a countable set of atomic sentences), to which the real world s is known to belong. The agent receives new information successively, in the form of an infinite stream (E0, E1, …,En , …) of inputs consisting of atomic sentences (“positive data”) En that are true in the real world s. The stream is required to be sound and complete with respect s, i.e. to consist of all the atomic sentences that are true in s and only those. A learning method H is a function that associates to any initial epistemic state S and any finite initial segment (E0,…, En) (of any length n) of any data stream, some “belief”, i.e. a subset H(S, E0,…, En) of S. The epistemic state S is “identifiable in the limit” if, for every world s in S and every sound and complete stream for s, there exists a finite stage after which H outputs the singleton {s} from then on. In belief-revision terms: the agent’s beliefs will converge to a stable justified belief that completely matches the truth. In epistemological terms: the agent will acquire “defeasible knowledge” of the real world. A learning method is “universal” if it can identify in the limit every epistemic state that is identifiable. Intuitively, a universal learning method is one that can learn everything that is learnable. The good news is that there are universal learning methods, and indeed that some very simple and well-known belief-revision methods (conditioning and lexicographic revision, both with respect to some well-chosen plausibility preorder on the original set S) are universal. These methods have the great advantage that they are “history-independent” (the successive beliefs depending at each stage only on the beliefs at the previous stage and on the new information) and “weakly conservative” (the beliefs do not change if the new information was already believed). The bad news is, first, that one has to give up most of the usual assumptions concerning the prior belief-revision structure: the plausibility order cannot be assumed to be total, well-founded or satisfying Grove’s Limit Condition. Second, conservatism has its limits: none of the even “more conservative” revision methods (prefered by Belief Revision researchers because they minimize the change to the plausibility order) is universal. Third, the bad news become worse if one insists on requiring that the learning method is actually “computable”: it follows from some learning-theoretic results of Dana Angluin that no computable method which is consistent with the AGM postulates can be universal (among the computable methods). These results reinforce and extend the conclusions reached in previous work by Kelly (and also in work by Baltag and Smets): there exists an inherent tension between the AGM requirement of minimizing belief change and the drive to maximize learning power. The tension cannot be relaxed by moving to probabilistic settings: on the contrary, Bayesian belief revision performs even worse than the above-mentioned methods! Nevertheless, to finish on a more optimistic tone, I sketch a natural way to modify to modify the above belief-revision methods and obtain a (non-conservative, but still history-independent) universal computable learning method.

Dr. Eric Joseph Pacuit (Center for Logic and Philosophy of Science, Tilburg University): Reasoning about and with protocols

Abstract.
While the standard notion of knowledge in Economics is Aumann’s absolutely certain, fully introspective, “irrevocable”, unrevisable type of knowledge (indicating the possession of “hard information”), philosophers argued for a long time that any realisticconcept of knowledge (that would cover our day-to-day usage and also address the challenges posed by skepticism and by the Gettier counterexamples) must be “softer”, less introspective and potentially defeasible (at least in certain circumstances), while still “safe” and “truth-tracking”. At the first sight, it might seem that these concepts have no place and no role to play in Economics. However, I will argue that this first impression is misleading: the the game-theorists pursuing the “belief-based approach” (rather than Aumann’s knowledge-based approach) have rediscovered softer types of knowledge previously considered by philosophers; that other soft concepts of knowledge proposed in the philosophical literature must come to play a central role in a deeper understanding of central game-theoretic issues, such as the meaning (and role of) rationality, the epistemic assumptions underlying solution concepts such as backward induction and trembling-hand equilibrium, common prior and the “agreeing to disagree” problem etc. In the same time, I argue that game-theoretic methods and concepts could be fruitful in dealing with issues in Epistemology, such as formalizing and investigating epistemological concepts using a game semantics, and “solving” central epistemic puzzles such as the Surprise Examination Puzzle using game theory. As unifying formalism, lying in between the two fields, I use Dynamic Epistemic Logic, enriched with ideas and concepts from Belief Revision Theory and Learning Theory.

For more information, please visit: http://nylogic.org/