Carnegie Mellon University

Lectures & Colloquia

Fall 2017

Thursday, September 14Philosophy Colloquium

Judith Degen, Stanford University
Talk Title: Informativeness in language production and comprehension
4:30 – 5:45pm, Baker Hall A53 – Steinberg Auditorium

Abstract: In producing and comprehending language, speakers and listeners engage in rich inference processes that involve reasoning about the (often noisy) linguistic signal's literal meaning, world knowledge, and the context of utterance. A fully-fledged theory of linguistic meaning requires formally describing and analyzing these inference processes, which has proven challenging because of the complexity of establishing which information is used and how it is integrated. Rational theories of language use starting with Grice have attempted to bring some order to this difficult analytical situation by positing conversational principles that listeners expect cooperative speakers to abide by. In particular, speakers are expected to include just enough -- but not too much -- information in their utterances for listeners to correctly infer their intended meaning from the literal meaning of their utterance, world knowledge, and the context of utterance.

But such theories have come under attack from psycholinguistics: speakers have been shown to produce both over- and underinformative utterances. In this talk, I will demonstrate that the assumption of (boundedly) rational linguistic agents can not only be upheld but even be explicitly modeled computationally to great explanatory effect. Using a combination of behavioral lab-based and web-based experiments, corpus analyses, and computational modeling, I will show that speakers are best modeled as trading off the contextual informativeness and production cost of their utterances. Listeners in turn are best modeled as integrating their beliefs about such speakers with their prior beliefs about likely meanings via Bayesian inference. The modeled data come from two prima facie very different phenomena -- the production of overinformative referring expressions and the interpretation of underinformative scalar expressions.

I will conclude that, rather than being wastefully overinformative, speakers systematically add information to the extent that doing so reduces their uncertainty about whether the listener will correctly infer their intended meaning. Similarly, rather than being uselessly underinformative, speakers systematically provide less information because listeners can be relied on to make good use of the available contextual information. Together, these findings implicate a linguistic system geared towards communicative efficiency.

Thursday, October 26 - Center for Formal Epistemology Talk
Slobodan Perović, University of Belgrade, Serbia
Talk Title: How Theories of Induction Can Streamline Measurements of Scientific Performance
12:00 – 1:30pm, Baker Hall 150 *Note different location

Abstract: An inductive approach to the scientific reasoning process can streamline operational assessments of scientific performance, e.g. citation metric analysis, by determining whether the scientific domain at stake is inductively suitable for such assessment. This approach aims to identify a methodologically coherent scientific pursuit, which ensures that the citation metrics track internal inductive dynamics and efficiency of the reasoning process in the analyzed domain. We demonstrate inductive streamlining (drawing on Formal/Machine Learning Theory) in the cases of high energy physics experimentation and phylogenetics research. A general test defining basic internal inductive and external practical conditions can ensure epistemically transparent operational, citation-based, analysis of scientific networks.

Friday, October 27Pure and Applied Logic Colloquium
Dana Scott, Carnegie Mellon University (emeritus)
Talk Title: What is Explicit Mathematics?
4:30-6:00pm Baker Hall A53 – Steinberg Auditorium.
Reception follows at 6p in BH135.

Abstract: Beginning in about 1975, the late Solomon Feferman started writing about ways of making “real” mathematics more explicit. He was much influenced at the time by writers such as Georg Kreisel, Errett Bishop, John Myhill, Per Martin-Löf, William Tait, to name a few. He then continued up to the end of his life with students and colleagues to expand on his vision — especially in developing detailed proof-theoretic comparisons between various axiomatic systems.

The speaker would like to raise the question anew as to whether there are other useful ways of being explicit and, thus, finding what can be learned about the content of mathematical arguments.

Thursday, November 16Philosophy Colloquium
Richard Zach, University of Calgary
Talk Title: The Origins of Modern First-order Logic
4:30 – 5:45pm, Baker Hall A53 – Steinberg Auditorium

Abstract:  The model and proof theory of classical first-order logic are a staple of introductory logic courses: we have nice proof systems that show that the validities of FOL are computably enumerable, a well-understood notion of models, validity, and consequence, completeness, undecidability, and other meta-logical results, and even decision procedures for the propositional and monadic fragments. The story of how these were developed in the 1920s, 30s, and even 40s is also a staple of introductory courses, but usually consists in simply a list of results and who obtained them when. What happened behind the scenes is much less well known. The talk will fill in some of that back story and show how philosophical, methodological, and practical considerations shaped the development of the conceptual framework and the direction of research in these formative decades.