Spring 2014

Thursday 23 January : Invited lecture

Speaker: Barbara Tomaszewicz

Time&Place: 16.45-18.30, Room DZ 6
Title: Comprehension of sentences with quantifiers: quantifier semantics and types of inference
Abstract: People talk about quantities all the time while describing the world. Natural language quantifiers semantically express relations between sets, e.g., ‘most’ in the sentence ‘Most cars are red’ tells us that the set of cars that are red is larger than the set of non-red cars. We can easily assess the conditions that make this sentence true/false, but how do we verify such sentences in real-life situations?
In the first part of my talk I will present my experiments on the verification of sentences with ‘most’ that indicate that when verifying such sentences against a visual display under time pressure, participants do not use the strategy that would be the most efficient to correctly choose ‘true/false’, but they use the strategy that is consistent with the semantic representation of the quantifier as specified in their mental lexicon.
In the second part, I will present further questions concerning the interpretation of sentences with quantifiers and inferences they give rise to. I will review the main experimental findings concerning the role of monotonicity in the complexities of reasoning with quantifiers.
 

Monday 3 February: Invited lecture

Speaker: Roberto Ciuni

Time&Place: 16.45-18.30, Room DZ 10
Title: Freedom’s an issue that can’t be computed!
Abstract: Matrix Game Logic (MGL) is a multi-agent modal logic that has been first introduced by Johan van Benthem. It models what an agent knows once she
performs an action—ex interim (e.i.) knowledge, what she prefers, and what she is free to accomplish. In this paper, we highlight some valid formulas of MGL that prove especially desirable in modeling freedom (and its relation with knowledge and preferences) and we show that MGL is undecidable. This is done by a mutual embedding between MGL and a particular group STIT logic which allows only for individual agents and their anti-coalitions (where the anti-coalition of agent i is the coalition Ags/i formed by all agents but i). Undecidability of MGL follows by property-transfer from the undecidability of this group STIT logic (which is in turn a consequence of already established results). We also show that the fragment of MGL containing only knowledge and preference operators is decidable, no matter the number of agents considered. In this sense, the freedom operator can be qualied the source of MGL’s undecidability.

 

Tuesday 25 February: Invited lecture

Speaker: Michiel van Lambalgen

Time&Place: 16.45-18.30, Room DZ 6
Title: Time in Kant’s Critique of Pure Reason
Abstract: In his first Critique, Kant offers a theory of time which is cognitively attractive because it presents temporal experience as the result of contributions from several distinct but interacting processes.This view is consistent with current research showing that the integration of these contributions is no easy task for the developing mind/brain. Kant also provides an informal description of the mathematical structure of time, from which it is clear that the number systems of classical mathematics do not fit his intended interpretation. For example, the temporal continuum is not composed of instants; instants correspond to state changes, hence there are relatively few instants; unlike geometrical points, instants are extended, hence divisible. It is not immediately obvious that Kant’s principles for time are consistent. We therefore provide an axiomatisation from which Kant’s principles can be derived. We use the formalism to some puzzling aspects of Kant’s views on time, space and mathematics.

 

Tuesday 4 March: Invited lecture

Speaker: Maria Aloni

Time&Place: 16.45-18.30, Room DZ 6
Title: On epistemic and deontic free choice (joint work with Michael Franke)
Abstract:A number of recent case-studies [Fălăuş, 2009; Aloni and Port, 2011;
Crnič, 2011] have independently provided evidence for the hypothesis
that free choice inferences associated with deontic modals more readily
penetrate compositional semantics than their epistemic counterparts.
Existing accounts of free choice are typically blind towards
differences between different kinds of modals and therefore have difficulties in
accounting for this kind of facts.
In this talk we will first review the relevant data and suggest an
explanation for the different free choice potential of deontic and
epistemic modals in terms of different stages of pragmatic
fossilization. Building on Aloni and Franke (2013) we will then propose a dynamic
account of fossilized implicatures which, while matching Chierchia’s et al.
(2008) predictions with respect to scalar implicatures, improves on their
account by explaining the difference between deontic and epistemic free choice
in terms of a difference of persistence of the free choice information.
Crucial to the proposed explanation is the adoption of an independently
motivated dynamic/anaphoric analysis of epistemic modals as operators
on local information states [Veltman, 1996; Yalcin, 2007].

 

Tuesday 18 March: TiLPS Colloquium

Speaker: Nina Gierasimczuk

Time&Place: 16.45-18.30, Room DZ 6
Title: Logic and Learning. An empirical test in a massively used online learning system.
Abstract: I will discuss the psychological relevance of a logical model for deductive reasoning. The talk will focus on a new way to analyze logical reasoning in a deductive version of the Mastermind game implemented within a popular Dutch online educational learning system (Math Garden). The model, based on he analytic tableaux method known from proof theory, allows predictions about the difficulty of Deductive Mastermind tasks (a proxy for working memory load). The empirical hypotheses were tested against a large group of students (over 37 thousand children, 5–12 years of age), which gave empirical difficulty ratings of all 321 game-items. The results show that our logical approach predicts these item ratings well, which supports the psychological relevance of the model.

The talk is based on joint work: Nina Gierasimczuk, Han van der Maas, and Maartje Raijmakers, An analytic tableaux model for Deductive Mastermind empirically tested with a massively used online learning system, Journal of Logic, Language and Information 2013.
 

Tuesday 1 April: Invited lecture

Speaker: Dominik Klein & Alessandra Marra

Time&Place: 16.45-18.30, Room DZ 6
Title: Norms, intentions and actions
Abstract: This talk focuses on the notion of agency, in particular the change that learning and accepting a norm trigger in agent’s actions and intentions. Current works on the logic of agency fall within two different groups: stit-frameworks which adopt a so-called “external perspective” (e.g., Belnap et al. 2001, Horty 2001) and represent agency in terms of possible outcomes of actions, and a variety of frameworks (e.g., Veltman 2012) which instead endorse an “internal perspective” and give the priority to agent’s intentions. The latter provide a limited account of the way intentions can be realized, while the former completely ignore the role of intentions as drives for action. We argue that both perspectives need to be taken into account, especially when dealing with the constraints triggered by a norm. We provide a formal model which represents both agent’s intentions (in terms of to-do-lists) and agent’s actions (through a tree-like structure). The acceptance of a norm triggers a change in the agent’s intentions in such a way that the agent now intends to bring about what the norm prescribes. Consequently, it affects also agent’s actions by restricting the set of admissible actions to the ones which permit her to fulfill the norm.
 

Tuesday 15 April: Invited lecture

Speaker: Christine Tiefensee (Bamberg) and Dominik Klein

Time&Place: 16.45-18.30, Room DZ 6
Title: The problem of moral conversion
Abstract:Minimalism threatens metaethical debate, or so many philosophers fear. So far, this fear has found expression in the problem of creeping minimalism, which is said to level pivotal metaethical differences by deflating all those notions – truth, fact, reference, assertion, possibly even belief and representation – which would be required to engage in meaningful metaethical debate. In this talk, we will draw attention to a new minimalist challenge to metaethics which has hitherto gone unnoticed. This ‘problem of moral conversion’ takes the following intriguing form:
It is clear that minimalism turns statements such as ‘It is true that slavery is wrong’ into moral claims: Since minimalists tell us that there is no substantive difference between asserting a statement and calling it true, declaring that it is true that slavery is wrong simply boils down to making the moral judgement that slavery is wrong. With statements about specific moral truths being turned into moral judgements, there exists strong intuition that we should expect the same moral conversion to apply to generalisations such as ‘There are moral truths’. However, it is surprisingly hard to make this intuition stick. If, and if so how, this intuition can be supported will be the focus of our talk.
 

Tuesday 6 May: Invited lecture

Speaker: Matthijs Westera (ILLC)

Time&Place: 16.45-18.30, Room DZ 6
Title: Why semantics is the waste basket.
Abstract: Pragmatics is often considered the waste basket of theories of language use, with pragmatic components of meaning (e.g., conversational implicatures) being considered defeasible, unreliable, flimsy, weak. Grice’s notion of ‘cancellability’, as well as recent experimental results on implicature, seem to support this view. I propose to turn this picture around: semantics contains everything that cannot be explained pragmatically. In the process, I address several, I think, widespread misconceptions concerning pragmatics, identify some shortcomings of current experiments, and argue for the necessary and actual reliability of pragmatic meaning. I shall say a bit on how the compositionality principle and theories of language change help organize the semantics wastebasket.
 

Tuesday 13 May: Invited lecture

Speaker: Lasha Abzianidze
Time&Place: 16.45-18.30, Room DZ 6
Title: How limited reasoning can account for other properties of belief systems
Abstract:In this talk I will introduce a belief logic that heavily employs the notion of complexity. In this logic, limited reasoning (that is one of the main characteristic of belief systems) is modelled using complexities, and it is shown how limited reasoning can be sufficient to account for the rest of the properties of belief systems such as:

a) It is possible to believe contradictions;

b) It is not necessary to believe all tautologies;

c) Belief systems are not necessarily closed under implication;

d) Belief systems are not necessarily closed under valid implication.

While introducing the belief logic, first, I will define the general version of the belief logic, where the complexity (i.e., cost) function will be characterized in an abstract way. Then it will be shown that one of the possibilities to flesh out the cost function is to define it in terms of tableau proofs with costs; therefore, a specific version of the belief logic (TABL) is obtained in this way. In the end, the sound and complete proof theory will be given for TABL.
 

Tuesday 27 May: Invited lecture

Speaker: Jaap Hage (Maastricht)

Time&Place: 16.45-18.30, Room DZ 6
Title: Deontic Logic Without Possible Worlds
Abstract:The use of possible worlds semantics for deontic logic is inspired by a parallel between deontic logic and more traditional alethic modal logic. It seems to make sense to say that a sentence expressing necessity (e.g. mathematicians are necessarily rational) is true iff the same sentence without the necessity (mathematicians are rational) is necessarily true, where being necessarily true is defined as true in all possible worlds. (The ‘seems’ is inspired by my lack of belief that what seems to be the case is actually the case. But that will not be the topic of my presentation.)
Analogously it seems attractive to say that an ought-sentence (e.g. mathematicians ought to be rational) is true iff the same sentence without ought is true in all possible worlds belonging to a particular category, e.g. ideal worlds, or otherwise ‘accessible’ worlds. In my presentation I will question the viability of this approach to deontic logic, both in a negative and in a constructive way. The negative way focuses on deontic detachment which is valid in Standard Deontic Logic and seems to be invalid in legal and moral reasoning. The constructive way consists in offering the outlines of an account of deontic logic that better fits ordinary normative reasoning and which has no need for possible worlds as a means to express deontic modality.
 

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