Supergroup Blast

[Shay Logan]

Dear Cheerful Logicians,

Some information about upcoming supergroup events can be found below. If you would like to have your group's events advertised here, please ask for permission to update the supergroup member groups calendar. 

To access the supergroup calendar, please follow this link: https://calendar.google.com/calendar?cid=ZGhoanNoanF1bGhmaG9xam5scDJlc2o0bDhAZ3JvdXAuY2FsZW5kYXIuZ29vZ2xlLmNvbQ

To access the member groups joint calendar, please follow this link: https://calendar.google.com/calendar?cid=aG8wNWljaGxkNXI2N2oyMnZvY3BzdmRoMWNAZ3JvdXAuY2FsZW5kYXIuZ29vZ2xlLmNvbQ

The latter calendar is currently fairly incomplete---if you represent a member group and would like your events to appear there, be sure to add them!

Supergroup Talk

Speaker: Kohei Kishida, University of Illinois Urbana-Champaign
Time and Date: Thursday May 28, 8pm GMT-5
Link: https://unimelb.zoom.us/j/846890369?pwd=TktZYmlIUGlYOU9ZaXFJcCt0TFJFZz09

Title: "Quantified Logic for Modal Reasoning and Theorizing” 

Abstract: Logicians and metaphysicians have developed various models and semantics of quantified modal logic.  These semantics come with ontological and metaphysical implications regarding the references of singular terms --- such as the necessity of Hesperus being Phosphorus.  My primary question in this talk is how these metaphysical facts can be a posteriori facts, as opposed to a matter of logic, of the sort that a cognizer can come to know.  The goal of this talk is to give a semantics that sheds new light on this aposteriority.  I will take an approach in terms of intensional logic that treats all singular terms, predicates, and quantifiers as uniformly intensional.  Combined with epistemic logic, my approach will provide a semantics and logic in which metaphysical principles regarding cross-world reference are substantial facts that a cognizer can both learn and use in their modal reasoning and theorizing.

Talks hosted by member groups: (Organized by date and time)

Host: Department of Logic and Philosophy of Science; University of California, Irvine.

Speaker: Guillermo Badia (University of Queensland)

Time and Date: Friday May 29 1500-1750 GMT-7

Link: https://uci.zoom.us/j/92258718270?pwd=QUx4ZmY2ZFh1MjhlWUIrTkhrQkNydz09
Title: How Much Propositional Logic Suffices for Rosser's Essential Undecidability Theorem?
Abstract: In this paper we explore the following question: how weak can a logic be for Rosser's essential undecidability result to be provable for a weak arithmetical theory? It is well known that Robinson's Q is essentially undecidable in intuitionistic logic, and P. Hájek proved it in the fuzzy logic BL for Grzegorczyk's variant of Q which interprets the arithmetic operations as non-total non-functional relations. We present a proof of essential undecidability in a much weaker substructural logic and for a much weaker arithmetic theory, a version of Robinson's R (with arithmetic operations also interpreted as mere relations). Our result is based on a structural version of the undecidability argument introduced by Kleene and we show that it goes well beyond the scope of the Boolean, intuitionistic, or fuzzy logic.

Host: Foundational Studies Bristol

Speaker: Gil Sagi (Haifa).
Time and Date: Friday, May 29th, 1500 GMT+1
Link: We will be using BlueJeans. Meeting url: https://bluejeans.com/841226547. (This will encourage you to download the app, just dismiss the download prompts, to see a "view in browser" link.) The BlueJeans meeting will be active from 2.45pm if you want to check your connection before the talk starts. 
Title: Logic and Natural Language: Commitments and Constraints

Abstract:  

Most of the contemporary research in logic is carried out with respect to formal languages. Logic, however, is said to be concerned with correct reasoning, and it is natural language that we usually reason in. Thus, in order to assess the validity of arguments in natural language, it is useful to formalize them: to provide matching arguments in a formal language where logical properties become perspicuous. It has been recognized in the literature that formalization is far from a trivial process. One must discern the logical from the nonlogical in the sentence, a process that requires theorizing that goes beyond the mere understanding of the sentence formalized (Brun 2014). Moreover, according to some, formalization is a form of explication, and it “involves creative and normative aspects of constructing logical forms” (ibid).

In previous work, I proposed a model-theoretic framework of “semantic constraints”, where there is no strict distinction between logical and nonlogical vocabulary. The form of sentences in a formal language is determined rather by a set of constraints on models. In the present paper, I show how this framework can also be used in the process of formalization, where the semantic constraints are conceived of as commitments made with respect to the language.

Please note: some people on the logic-supergroup list have already seen this talk. Contact Gil if you want to check if you've seen it already.

Other Announcements:

The Web School on Logic, Language, and Information is happening July 11-19. More information at https://www.brandeis.edu/nasslli2020/. Of particular interest to our members might be the workshop called Natural Logic Meets Machine Learning; more info at https://typo.uni-konstanz.de/naloma20/.