ILLC-LIRa

illc-lira@list.uva.nl

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LIRa session: Salvador Mascarenhas (Thursday, 10 February 16:30)
by LIRa Seminar 06 Feb '22

06 Feb '22

Dear all, We will have our next LIRa session on Thursday, 10 February 16:30. Please use our recurring zoom link: https://uva-live.zoom.us/j/88142993494?pwd=d1BsQWR4T2UyK0Job29YNThjaGRkUT09 (Meeting ID: 881 4299 3494, Passcode: 352984) You can find the details of the talk below. Speaker: Salvador Mascarenhas (Institut Jean-Nicod, Department of Cognitive Studies, Ecole Normale Supérieure) Date and Time: Thursday, February 10th 2022, 16:30-18:00, Amsterdam time. Venue: online. Title: Question-answer dynamics and confirmation theory in reasoning with alternatives Abstract. Informally, confirmation-theoretic approaches to reasoning propose that humans often do not compute posterior probabilities, as the usual norms for rationality recommend, but instead ask themselves to what extent a piece of information (the evidence) supports a particular conclusion (the hypothesis). This family of theories yields our best accounts of the conjunction fallacy and related reasoning problems. Yet from an empirical standpoint, its full scope is still unknown: just how pervasive is this decision-making strategy in human inference making? Additionally, the computational-level justification for confirmation-theoretic reasoning is still an open question: why would humans deploy a mode of reasoning that so often fails to maximize the probability that the conclusions we draw are true? This talk tries to contribute to answering these two questions. I show that illusory inferences with alternatives, a broad paradigm of deductive fallacies, require confirmation-theoretic tools and cannot be accounted for within traditional deductive theories or with probabilistic theories that exclusively use posterior probabilities as the standard for rationality. Additionally, I present two experiments on the lawyers-and-engineers paradigm from Kahneman and Tversky (1973), showing that errors in variants of this probabilistic task also require confirmation-theoretic notions. One of the experiments applies a simplified version of Kahneman and Tversky's original paradigm to carefully normed materials, allowing for more fine-grained theory testing. The other is a visual version of the task, using ad hoc concepts where the underlying probabilistic distributions are completely transparent to participants. I then outline a theory that combines confirmation-theoretic tools with the erotetic theory of reasoning (Koralus and Mascarenhas, 2013, 2018), an account of naive deduction where question-answer dynamics are at the root of failures of reasoning in the cases at hand. I argue that confirmation-theoretic reasoning plausibly arises from the semantics and pragmatics of questions and answers, and I propose that this fact offers the beginning of an explanation for the pervasiveness of confirmation-theoretic reasoning. Hope to see you there! The LIRa team

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LIRa session: Wesley Holliday (tomorrow, Thursday, 3 February 18:15)
by LIRa Seminar 02 Feb '22

02 Feb '22

Dear all, We will have our next LIRa session tomorrow, on Thursday, 3 February 18:15. Please use our recurring zoom link: https://uva-live.zoom.us/j/88142993494?pwd=d1BsQWR4T2UyK0Job29YNThjaGRkUT09 (Meeting ID: 881 4299 3494, Passcode: 352984) You can find the details of the talk below. Speaker: Wesley Holliday (University of California, Berkeley) NOTE THE UNUSUAL TIME! Date and Time: Thursday, February 3rd 2022, 18:15-19:45, Amsterdam time. Venue: online. Title: The Orthologic of Epistemic Modals Abstract. My talk will be based on a joint paper with Matthew Mandelkern (NYU), “The Orthologic of Epistemic Modals” (https://escholarship.org/uc/item/0ss5z8g3). Epistemic modals have peculiar logical features that are challenging to account for in a broadly classical framework. For instance, while a sentence of the form ‘p, but it might be that not p’ appears to be a contradiction, 'might not p' does not entail 'not p', which would follow in classical logic. Likewise, the classical laws of distributivity and disjunctive syllogism fail for epistemic modals. Existing attempts to account for these facts generally either under- or over-correct. Some theories predict that 'p and might not p', a so-called epistemic contradiction, is a contradiction only in an etiolated sense, under a notion of entailment that does not allow substitution of logical equivalents; these theories underpredict the infelicity of embedded epistemic contradictions. Other theories savage classical logic, eliminating not just rules that intuitively fail but also rules like non-contradiction, excluded middle, De Morgan’s laws, and disjunction introduction, which intuitively remain valid for epistemic modals. In our paper, we aim for a middle ground, developing a semantics and logic for epistemic modals that makes epistemic contradictions genuine contradictions and that invalidates distributivity and disjunctive syllogism but that otherwise preserves classical laws that intuitively remain valid. We start with an algebraic semantics, based on ortholattices instead of Boolean algebras, and then propose a more concrete possibility semantics, based on partial possibilities related by compatibility. Both semantics yield the same consequence relation, which we axiomatize. Then we show how to extend our semantics to explain parallel phenomena involving probabilities and conditionals. The goal throughout is to retain what is desirable about classical logic while accounting for the non-classicality of epistemic vocabulary. Hope to see you there! The LIRa team

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LIRa session: Wesley Holliday (Thursday, 3 February 18:15)
by LIRa seminar 28 Jan '22

28 Jan '22

Dear all, We will have our next LIRa session on Thursday, 3 February 18:15. Please use our recurring zoom link: https://uva-live.zoom.us/j/88142993494?pwd=d1BsQWR4T2UyK0Job29YNThjaGRkUT09 (Meeting ID: 881 4299 3494, Passcode: 352984) You can find the details of the talk below. Speaker: Wesley Holliday (University of California, Berkeley) NOTE THE UNUSUAL TIME! Date and Time: Thursday, February 3rd 2022, 18:15-19:45, Amsterdam time. Venue: online. Title: The Orthologic of Epistemic Modals Abstract. My talk will be based on a joint paper with Matthew Mandelkern (NYU), “The Orthologic of Epistemic Modals” ( https://escholarship.org/uc/item/0ss5z8g3 ). Epistemic modals have peculiar logical features that are challenging to account for in a broadly classical framework. For instance, while a sentence of the form ‘p, but it might be that not p’ appears to be a contradiction, 'might not p' does not entail 'not p', which would follow in classical logic. Likewise, the classical laws of distributivity and disjunctive syllogism fail for epistemic modals. Existing attempts to account for these facts generally either under- or over-correct. Some theories predict that 'p and might not p', a so-called epistemic contradiction, is a contradiction only in an etiolated sense, under a notion of entailment that does not allow substitution of logical equivalents; these theories underpredict the infelicity of embedded epistemic contradictions. Other theories savage classical logic, eliminating not just rules that intuitively fail but also rules like non-contradiction, excluded middle, De Morgan’s laws, and disjunction introduction, which intuitively remain valid for epistemic modals. In our paper, we aim for a middle ground, developing a semantics and logic for epistemic modals that makes epistemic contradictions genuine contradictions and that invalidates distributivity and disjunctive syllogism but that otherwise preserves classical laws that intuitively remain valid. We start with an algebraic semantics, based on ortholattices instead of Boolean algebras, and then propose a more concrete possibility semantics, based on partial possibilities related by compatibility. Both semantics yield the same consequence relation, which we axiomatize. Then we show how to extend our semantics to explain parallel phenomena involving probabilities and conditionals. The goal throughout is to retain what is desirable about classical logic while accounting for the non-classicality of epistemic vocabulary. Hope to see you there! The LIRa team

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Recording available: Exploring Baltag’s Universe
by illc-lira＠list.uva.nl 24 Jan '22

24 Jan '22

Dear all, We are happy to announce that the recordings of our workshop “Exploring Baltag’s Universe” are now available: https://projects.illc.uva.nl/lgc/seminar/2022/01/exploring-baltags-universe… This workshop was organized by Johan van Benthem and Soroush Rafiee Rad on the 15th of January for our colleague and friend Alexandru Baltag on the occasion of his birthday and featured short talks by Alexandru’s long-standing colleagues and collaborators including Samson Abramsky, Sonja Smets, Fenrong Liu, Alexander Kurz, Luís Soares Barbosa, Nick Bezhanishvili, Kevin Kelly, Larry Moss and Johan van Benthem. Our first LIRa session this year will be next week, on Thursday 3 February with Wesley Holliday, at 18:15 (note the unusual time). A regular announcement will follow. With best wishes, the LIRa team

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LIRa-related event with Fenrong Liu on January 27
by Anthi Solaki 19 Jan '22

19 Jan '22

Dear all, We would like to bring the following LIRa-related event to your attention: ======= DEON SEMINAR ON JANUARY 27 AT 1PM CET ========= RE: DEON seminar series on January 27 The Society of Deontic Logic and Normative Systems (DEON) has launched an online seasonal seminar series designed to promote interdisciplinary cooperation amongst scholars interested in linking the formal-logical study of normative concepts, normative language and normative systems with computer science, artificial intelligence, linguistics, philosophy, organization theory and law. We view the seminar series as an opportunity to keep in touch with the DEON community and listen in or contribute to presentations and informal discussions on ongoing work. Everyone who is interested in this wonderful area and its questions is welcome. We are happy to announce that our speaker for the DEON winter seminar will be Fenrong Liu (Professor of Logic, Tsinghua University and University of Amsterdam). Date and time: January 27, 1pm – 2:30pm CET Zoom link: https://uva-live.zoom.us/j/89287004976 (Meeting ID: 892 8700 4976) Virtual gathering: join us for a virtual gathering on wonder.me after the talk! No registration needed, just follow this link: https://www.wonder.me/r?id=3536c0e5-c486-4ff2-876a-91e569f4190b. Title: From a two-level perspective on preference to deontic logic Abstract: By 'two-level perspective on preference' I mean the following two aspects: a) given a set of propositions, possibly ordered, we can derive preference relations over individuals. b) Given preference relations between individuals, we can lift them to an ordering over sets of individuals. After introducing the latest studies in these two lines, I will focus on their relevance to deontic logic. In particular, I will illustrate with the lifted Egli-Milner order and its connection to notions of conditional ought and conditional permission. References: 1. Fenrong Liu. Reasoning about Preference Dynamics, Springer, 2011. 2. Johan Benthem, Davide Grossi & Fenrong Liu. Priority Structures in Deontic Logic, Theoria 80 (2):116-152, 2014. 3. Chenwei Shi & Yang Sun. Logic of Convex Order. Studia Logica 109: 1019-1047, 2021. If you are interested in the upcoming events in this series, subscribe here: https://icr.uni.lu/deonticlogic/mailinglist.html. We hope to see you on the 27th of January! Ilaria Canavotto, Huimin Dong, and Réka Markovich DEON Seminar Series organizers ---------------------------------------------------------------------- On behalf of the LIRa team, Anthi

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Birthday workshop: Exploring Baltag’s Universe (tomorrow, Saturday, 15 January 13:45)
by LIRa Seminar 14 Jan '22

14 Jan '22

Dear All, Tomorrow, Saturday 15 January 2022, we will have our online workshop “Exploring Baltag’s Universe”. This is a workshop organized for our colleague and friend Alexandru Baltag on the occasion of his 55th birthday. The workshop will feature short talks by Alexandru's long-standing colleagues and collaborators including Samson Abramsky, Sonja Smets, Fenrong Liu, Nick Bezhanishvili, Luís Soares Barbosa, Alexander Kurz, Kevin Kelly, Larry Moss, and Johan van Benthem. The program will start at 13:45 with welcome words and continues at 14:00 with the lectures till 19:00. Please see https://tinyurl.com/thebaltagworkshop for the full program and details of the talks. You can join the event via this zoom link: https://uva-live.zoom.us/j/88657056244 For more information please get in touch with Soroush Rafiee Rad at s.rafieerad(a)uva.nl We hope to see you all tomorrow at the celebration. The LIRa team

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Birthday workshop: Exploring Baltag’s Universe (Saturday, 15 January 13:45)
by LIRa Seminar 11 Jan '22

11 Jan '22

Dear all, On 15 January 2022 we will be “Exploring Baltag’s Universe”, an online workshop organized for our colleague and friend Alexandru Baltag on the occasion of his birthday. The workshop will feature short talks by Alexandru's long-standing colleagues and collaborators including Samson Abramsky, Sonja Smets, Fenrong Liu, Alexander Kurz, Luís Soares Barbosa, Nick Bezhanishvili, Kevin Kelly, Larry Moss and Johan van Benthem. The programme will start at 13:45 with welcome words and continues at 14:00 with the lectures till 19:00. We will provide a more detailed programme on the LIRa mailing list later this week. You are warmly invited to join the celebration on 15 January. This event is associated with World Logic Day! The zoom-link to the event will be announced later. For more information please get in touch with Soroush Rafiee Rad at s.rafieerad(a)uva.nl. Hope to see you there! The LIRa team

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LIRa Session: Branden Fitelson (tomorrow, Thursday, 16 December 16:30)
by LIRa Seminar 15 Dec '21

15 Dec '21

Dear all, We will have our next LIRa session tomorrow, on Thursday, 16 December 16:30. Please use our recurring zoom link: https://uva-live.zoom.us/j/88142993494?pwd=d1BsQWR4T2UyK0Job29YNThjaGRkUT09 (Meeting ID: 881 4299 3494, Passcode: 352984) You can find the details of the talk below. Speaker: Branden Fitelson (Northeastern University, Boston) Date and Time: Thursday, December 16th 2021, 16:30-18:00, Amsterdam time. Venue: online. Title: Probabilities of Conditionals & Conditional Probabilities --- Revisited Abstract. Lewis's (1976) triviality argument against The Equation (a.k.a, Adams's Thesis) rests on an implausibly strong presupposition about the nature of (epistemic) rational requirements. Interestingly, Lewis (1980) later rejected this presupposition. In his discussion of the Principal Principle, Lewis assumes something weaker, and more reasonable, about the nature of rational requirements. In this paper, I explain how to apply the insights of Lewis (1980) to repair Lewis's earlier (1976) discussion. This leads to a more reasonable rendition of The Equation --- one which is (a) immune from triviality, and (b) a better candidate for a (bona fide) rational requirement. Hope to see you there! The LIRa team

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LIRa Session: Branden Fitelson (Thursday, 16 December 16:30)
by LIRa Seminar 10 Dec '21

10 Dec '21

Dear all, We will have our next LIRa session on Thursday, 16 December 16:30. Please use our recurring zoom link: https://uva-live.zoom.us/j/88142993494?pwd=d1BsQWR4T2UyK0Job29YNThjaGRkUT09 (Meeting ID: 881 4299 3494, Passcode: 352984) You can find the details of the talk below. Speaker: Branden Fitelson (Northeastern University, Boston) Date and Time: Thursday, December 16th 2021, 16:30-18:00, Amsterdam time. Venue: online. Title: Probabilities of Conditionals & Conditional Probabilities --- Revisited Abstract. Lewis's (1976) triviality argument against The Equation (a.k.a, Adams's Thesis) rests on an implausibly strong presupposition about the nature of (epistemic) rational requirements. Interestingly, Lewis (1980) later rejected this presupposition. In his discussion of the Principal Principle, Lewis assumes something weaker, and more reasonable, about the nature of rational requirements. In this paper, I explain how to apply the insights of Lewis (1980) to repair Lewis's earlier (1976) discussion. This leads to a more reasonable rendition of The Equation --- one which is (a) immune from triviality, and (b) a better candidate for a (bona fide) rational requirement. Hope to see you there! The LIRa team

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LIRa Session: Giorgio Sbardolini (tomorrow, Thursday, 9 December 16:30)
by LIRa Seminar 08 Dec '21

08 Dec '21

Dear all, We will have our next LIRa session tomorrow, on Thursday, 9 December 16:30. Please use our recurring zoom link: https://uva-live.zoom.us/j/88142993494?pwd=d1BsQWR4T2UyK0Job29YNThjaGRkUT09 (Meeting ID: 881 4299 3494, Passcode: 352984) You can find the details of the talk below. Speaker: Giorgio Sbardolini Date and Time: Thursday, December 9th 2021, 16:30-18:00, Amsterdam time. Venue: online. Title: Coordination without Common Knowledge Abstract. It is fairly well understood how rational agents coordinate by means of common knowledge. At least occasionally, we are rational, and we coordinate. Even so, often it doesn’t seem that we coordinate by reasoning about what we both know (and we know that we know and so on). Sometimes we coordinate without common knowledge, but how? I’ll present some work in progress in which I try to make sense of a weak notion of rationality on which coordination without common knowledge is rational. I will present two (tentative) ways of making sense of this idea: one using Iterated Best Response reasoning and one using Dynamic Epistemic Actions. The two approaches are not equivalent, and I’m also interested in what connections there might be between these two ways of studying rational action. Hope to see you there! The LIRa team

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