philog.arthurpaulpedersen.org

A link for each seminar is to be posted here shortly before it begins.

Joe Halpern

Department of Computer Science
Cornell University

Actual Causality: A Survey

Abstract. What does it mean that an event C "actually caused" event E? The problem of defining actual causation goes beyond mere philosophical speculation. For example, in many legal arguments, it is precisely what needs to be established in order to determine responsibility. (What exactly was the actual cause of the car accident or the medical problem?) The philosophy literature has been struggling with the problem of defining causality since the days of Hume, in the 1700s. Many of the definitions have been couched in terms of counterfactuals. (C is a cause of E if, had C not happened, then E would not have happened.) In 2001, Judea Pearl and I introduced a new definition of actual cause, using Pearl's notion of structural equations to model counterfactuals. The definition has been revised twice since then, extended to deal with notions like "responsibility" and "blame", and applied in databases and program verification. I survey the last 15 years of work here, including joint work with Judea Pearl, Hana Chockler, and Chris Hitchcock. The talk will be completely self-contained.

Jongjin Kim

Korea University

Buddha versus Popper

Abstract. We discuss two approaches to life: presentism and futurism. We locate presentism within various elements of Buddhism, in the form of advice to live in the present and not to allow the future to hinder us from living in the ever present now. By contrast, futurism, which we identify with Karl Popper, advises us to think of future consequences before we act, and to act now for a better future. Of course, with its emphasis on a well-defined path to an ideal future ideally culminating in enlightenment, Buddhism undoubtedly has elements of futurism as well. We do not intend to determine which of these two approaches to time is more dominant in Buddhism, nor how the two approaches are best understood within Buddhism; but simply we intend to compare and contrast these two approaches, using those presentist elements of Buddhism as representative of presentism while contrasting them with those elements of futurism to be found in Popper and others. We will discuss various aspects of presentism and futurism, such as Ruth Millikan’s Popperian animal, the psychologist Howard Rachlin’s social and temporal discounting, and even the popular but controversial idea, YOLO (you only live once). The primary purpose of this paper is to contrast one with the other. The central question of ethics is: How should one live? Our variation on that question is: When should one live? We conjecture that the notion of flow, developed by Csikszentmihalyi, may be a better optimal choice between these two positions.

Rohit Parikh

Computer Science, Mathematics, Philosophy
City University of New York

The Logic of Knowledge Based Obligation

Abstract. Our obligations depend on what we know. If we do not know that we need to do X then there is no obligation to actually do X. However, sometimes there is also an obligation to know and hence also an obligation to inform. We look into the temporal logic of such issues, relying on work by John Horty and by Parikh and Ramanujam.

Jayant Shah

Department of Mathematics
Northeastern University

Discussion. Christian Trudeau's "From the Bankruptcy Problem and its Concede-and-Divide Solution to the Assignment Problem and its Fair Division Solution."

Nur Dean

Farmingdale State College

Polarized Population Under Imitation Dynamics in Complex Networks

Abstract. Evolutionary game theory is applied in a variety of settings, ranging from economics to socio-technical networks. The core concept in evolutionary game theory is evolutionary dynamics, which determines the composition of strategies in the population at steady state. Most evolutionary dynamics are modelled to descriptively showcase the utility derived from interactions between random pairs of players in well-mixed populations, or random pairs of neighbours in structured populations. In real-life social and socio-technical networks, it is more appropriate to evaluate a player's utility as a collection of interactions with its neighbours. To understand this; in practice, people form opinions by means of observation and imitation, by not just one friend, but a collection of friends. This paper displays a variation of the pairwise imitation dynamics where players imitate the most well-off neighbour. This process is memory-less i.e., players only use the outcome of the current game to determine their strategies in subsequent games. Empirical results demonstrate that in real-life social networks, this imitation dynamic leads to a polarized population with games that have multiple pure strategy Nash equilibria such as the Stag-Hunt game and anti-coordination games like Hawk-Dove, where an "undecided" population indefinitely swings between two strategies.

Jenn McDonald

CUNY Graduate Center

Causal Models as Relative to Modal Profile

Abstract. A recent development in the philosophy of causation uses the framework of causal models, such as structural equation models, to define actual causation. There are two components to such a definition. The first is to identify how to define causation in terms of a given model or given class of models. The second is to provide an account of what qualifies models as given – or apt – such that they can be plugged into the first stage. A naïve hypothesis is that a model is apt just in case it is accurate. In this talk I will argue, however, that the accuracy of a model is not a determinate function of a model, an interpretation, and a situation. A given model on a given interpretation can still be deemed accurate or inaccurate of the same situation. As I demonstrate, this is because accuracy is relative to a set of background possibilities – what I call a modal profile. I argue that this reveals a heretofore hidden element in how causal models represent – that models represent situations only relative to some modal profile or other. I propose that this calls for an additional component of an interpretation: an interpretation is an assignment of content to the variables and a specification of modal profile.

Rohit Parikh

Computer Science, Mathematics, Philosophy
City University of New York

Covid-19 and Knowledge based Computation

Abstract. The purpose of this project is to combine insights from the logic of knowledge (act according to what you know), and graph theory (spread of infection follows the edges of a graph). We show how knowledge based algorithms can be used to combine safety with economic and social activity.

Arthur Paul Pedersen

Department of Computer Science
City University of New York

Discussion.Chapter 6, "Two-Person Cooperative Games" (spec. pp. 114-124), from R. Duncan Luce and Howard Raiffa's Games and Decisions.

Jayant Shah

Department of Mathematics
Northeastern University

Discussion. Robert J. Aumann and Michael Maschler's "Game Theoretic Analysis of a Bankruptcy Problem from the Talmud," Journal of Economic Theory, 36(2): 195-213, August 1985.

Rohit Parikh

Computer Science, Mathematics, Philosophy
City University of New York

Discussion. Jan van Eijck and Rineke Verbrugge's"Formal Approaches to Social Procedures," from Stanford Encyclopedia of Philosophy

Rohit Parikh

Computer Science, Mathematics, Philosophy
City University of New York

Applications of Epistemic Logic to Society

Rohit Parikh

Computer Science, Mathematics, Philosophy
City University of New York

Discussion.Chapter 4, "Conflict," from A.D. Taylor and A.M. Pacelli's Mathematics and Politics: Strategy, Voting, Power and Proof

Maryam Bibi

Brookyln College
City University of New York

Discussion.Chapter 3, "Political Power," from A.D. Taylor and A.M. Pacelli's Mathematics and Politics: Strategy, Voting, Power and Proof

Rohit Parikh

Computer Science, Mathematics, Philosophy
City University of New York

Discussion.Chapter 2, "Yes-No Voting," from A.D. Taylor and A.M. Pacelli's Mathematics and Politics: Strategy, Voting, Power and Proof

Rohit Parikh

Computer Science, Mathematics, Philosophy
City University of New York

Discussion.Chapter 1, "Social Choice," from A.D. Taylor and A.M. Pacelli's Mathematics and Politics: Strategy, Voting, Power and Proof

Barbara H. Partee

Department of Linguistics
University of Massachusetts Amherst

Language and Logic: Ideas and Controversies in the History of Formal Semantics ‖Slides

Simon Huttegger

Department of Logic and Philosophy of Science
University of California, Irvine

Discussion. On de Finetti's representation theorem for exchangeability, Chapter 7, "Unification," from Persi Diaconis and Brian Skyrms' Ten Great Ideas about Chance

Rohit Parikh

Computer Science, Mathematics, Philosophy
City University of New York

Discussion. Chapter 8, "Algorithmic Randomness," from Persi Diaconis and Brian Skyrms' Ten Great Ideas about Chance

Arthur Paul Pedersen

Department of Computer Science
City University of New York

Discussion. Chapter 6, "Inverse Inference: From Bayes and Laplace to Modern Statistics," from Persi Diaconis and Brian Skyrms' Ten Great Ideas about Chance

Cailin O'Connor

Department of Logic & Philosophy of Science
University of California, Irvine

Abstract. Standard accounts of convention include notions of arbitrariness. But many have conceived of conventionality as an all or nothing affair. In this paper, I develop a framework for thinking of conventions as coming in degrees of arbitrariness. In doing so, I introduce an information theoretic measure intended to capture the degree to which a solution to a certain social problem could have been otherwise. As the paper argues, this framework can help improve explanation aimed at the cultural evolution of social traits. Good evolutionary explanations recognize that most functional traits are also conventional, at least to some degree, and vice versa.

Paul Krasucki

Security
Accenture (Fortune Global 500 Company)

Discussion. Chapter 5, "Mathematics," from Persi Diaconis and Brian Skyrms' Ten Great Ideas about Chance

Jayant Shah

Department of Mathematics
Northeastern University

Discussion. Chapter 4, "Frequency," from Persi Diaconis and Brian Skyrms' Ten Great Ideas about Chance

Ada Coronado

Department of Philosophy
The Graduate Center, CUNY

Discussion. Chapter 3, "Psychology," from Persi Diaconis and Brian Skyrms' Ten Great Ideas about Chance

Todd Stambaugh

Department of Mathematics and Computer Science
John Jay College, CUNY

Coincidence of Bargaining Solution ‖Slides

Abstract. In 1950, a month before his dissertation on non-coorperative games was accepted at Princeton and 3 months after his famous solution concept was announced to the world in the Proceedings of the National Academy of Sciences, John Nash had published "The Bargaining Problem," in which he proposed the titular problem and gave the first solution. In the years after, several other solutions were developed, notably those by Kalai and Smorodinsky, Kalai, and Harsanyi. In this talk I will outline the problem itself, present four different solutions, and describe the precise conditions under which various sets of these solutions coincide.

Larry Moss

Department of Mathematics
Indiana University

Discussion. Chapter 2, "Judgment," from Persi Diaconis and Brian Skyrms' Ten Great Ideas about Chance

José Luis Bermúdez

Department of Philosophy
Texas A&M University

Rational Frames?