Formal Philosophy

Logic at Columbia University

Suppes Lectures by Easwaran

by Yang Liu

SUPPES LECTURES
by Kenny Easwaran (Texas A&M University)

Graduate Workshop
Measuring Beliefs
3:00-5:00 pm, Friday, March 31, 2017
716 Philosophy Hall, Columbia University

Departmental Lecture
An Opinionated Introduction to the Foundations of Bayesianism
6:15-8:00 pm, Tuesday, April 4, 2017
716 Philosophy Hall, Columbia University
Reception to follow in 720 Philosophy Hall

Public Lecture
Unity in Diversity: “The City as a Collective Agent”
4:10-6:00 pm, Thursday, April 6, 2017
603 Hamilton Hall, Columbia University

Parikh: An Epistemic Generalization of Rationalizability

by Robby

UNIVERSITY SEMINAR ON LOGIC, PROBABILITY, AND GAMES
An Epistemic Generalization of Rationalizability
Rohit Parikh (CUNY)
4:10 pm, Friday, March 24th, 2017
Faculty House, Columbia University

Abstract. Rationalizability, originally proposed by Bernheim and Pearce, generalizes the notion of Nash equilibrium. Nash equilibrium requires common knowledge of strategies. Rationalizability only requires common knowledge of rationality. However, their original notion assumes that the payoffs are common knowledge. I.e. agents do know what world they are in, but may be ignorant of what other agents are playing.

We generalize the original notion of rationalizability to consider situations where agents do not know what world they are in, or where some know but others do not know. Agents who know something about the world can take advantage of their superior knowledge. It may also happen that both Ann and Bob know about the world but Ann does not know that Bob knows. How might they act?

We will show how a notion of rationalizability in the context of partial knowledge, represented by a Kripke structure, can be developed.

Gaifman and Liu: A Simpler and More Realistic Subjective Decision Theory

by Robby

UNIVERSITY SEMINAR ON LOGIC, PROBABILITY, AND GAMES
Essential Simplifications of Savage’s Subjective Probabilities System
Haim Gaifman (Columbia University) and
Yang Liu (University of Cambridge)
4:10 pm, Friday, November 18th, 2016
Faculty House, Columbia University

Abstract. This talk covers: (I)  A short outline of Savage’s system; (II) A new mathematical technique for handling “partitions with errors” that leads to a simplification that Savage tried but did not succeed in getting, which leads to the definition of numerically precise probabilities without the σ-algebra assumption; (III) Some philosophical analysis of the notion of idealized rational agent, which is commonly used as a guideline for subjective probabilities.

Some acquaintance with Savage’s system is helpful, but (I) is added in order to make for a self-contained presentation. The talk is based on a joint work by the authors titled “A Simpler and More Realistic Subjective Decision Theory”. Please email Robby for an introductory section of the present draft of the paper.

More about the seminar here.

We will be having dinner right after the meeting at the faculty house. Please let Robby know if you will be joining us so that he can make an appropriate reservation (please be advised that at this point the university only agrees to cover the expenses of the speaker and the rapporteur and that the cost for all others is $30, payable by cash or check).

Price: Heart of DARCness

by Robby

UNIVERSITY SEMINAR ON LOGIC, PROBABILITY, AND GAMES
Heart of DARCness
Huw Price (University of Cambridge)
4:10 pm, Thursday, October 13th, 2016
Faculty House, Columbia University

Abstract. Alan Hajek has recently criticised the thesis that Deliberation Crowds Out Prediction (renaming it the DARC thesis, for ‘Deliberation Annihilates Reflective Credence’). Hajek’s paper has reinforced my sense that proponents and opponents of this thesis often talk past one other. To avoid confusions of this kind we need to dissect our way to the heart of DARCness, and to distinguish it from various claims for which it is liable to be mistaken. In this talk, based on joint work with Yang Liu, I do some of this anatomical work. Properly understood, I argue, the heart is in good shape, and untouched by Hajek’s jabs at surrounding tissue. Moreover, a feature that Hajek takes to be problem for the DARC thesis – that it commits us to widespread ‘credal gaps’ – turns out to be a common and benign feature of a broad class of cases, of which deliberation is easily seen to be one.

More about the seminar here.

We will be having dinner right after the meeting at the faculty house. Please let Robby know if you will be joining us so that he can make an appropriate reservation (please be advised that at this point the university only agrees to cover the expenses of the speaker and the rapporteur and that the cost for all others is $30, payable by cash or check).

Diaconis: The Problem of Thinking Too Much

by Yang Liu

UNIVERSITY SEMINAR ON LOGIC, PROBABILITY, AND GAMES
The Problem of Thinking Too Much

Persi Diaconis (Stanford University)
4:10 pm, Friday, September 16, 2016
Faculty House, Columbia University

Abstract. We all know the problem: you sit there, turning things over, and nothing gets done.  Indeed, there are examples where “quick and dirty,” throwing away information, dominate.  My examples wil be from Bayesian statistics and the mathematics of coin tossing, but I will try to survey some of the work in psychology, philosophy, and economics.

More about the seminar here.

We will be having dinner right after the meeting at the faculty house. Please let Robby know if you will be joining us so that he can make an appropriate reservation (please be advised that at this point the university only agrees to cover the expenses of the speaker and the rapporteur and that the cost for all others is $25, payable by cash or check).

 

Conference on Reconciling Nominalism and Platonism

by Yang Liu

RECONCILING NOMINALISM AND PLATONISM IN THE PHILOSOPHY OF MATHEMATICS
Department of Philosophy, Columbia University
April 22–23, 2016

FRIDAY APRIL 22 (Philosophy Hall, Room 716)

14:00–14:15
Achille Varzi (Columbia University), Marco Panza (IHPST)
Welcome and Introduction
14:15-15:45
John Burgess (Princeton University)
Reconciling Anti-Nominalism and Anti-Platonism in the Philosophy of Mathematics
15:45–16:00 Break
16:00-17:30
Haim Gaifman (Columbia University)
Reconfiguring the Problem: “Platonism” as Objective, Evidence-transcendent Truth
17:30-19:00
Sébastien Gandon (Université Blaise Pascal)
Describing What One is Doing. A Philosophy of Action Based View of Mathematical Objectivity

SATURDAY, APRIL 23 (Philosophy Hall, Room 716)

9:30–11:00
Mirna Džamonja (University of East Anglia and IHPST)
An Unreasonable Effectiveness of ZFC Set Theory at the Singular Cardinals
11:00–11:30 Break
11:30–13:00
Hartry Field (New York University)
Platonism, Indispensability, Conventionalism
13:00–15:00 Lunch
15:00-16:30
Justin Clarke-Doane (Columbia University)
The Benacerraf Problem in Broader Perspective
16:30–17:00 Break
17:00-18:30
Michele Friend (George Washington University)
Is the Pluralist Reconciliation between Nominalism and Platonism too Easy?
18:30 Conclusions