Rasmus Kraemmer Rendsvig

Pluralistic ignorance in the bystander effect: informational dynamics of unresponsive witnesses in situations calling for intervention

The goal of the present paper is to construct a formal explication of the pluralistic ignorance explanation of the bystander effect. The social dynamics leading to inaction is presented, decomposed, and modeled using dynamic epistemic logic augmented with ‘transition rules’ able to characterize agent behavior. Three agent types are defined: First Responders who intervene given belief of accident; City Dwellers, capturing ‘apathetic urban residents’ and Hesitators, who observe others when in doubt, basing subsequent decision on social proof. It is shown how groups of the latter may end in a state of pluralistic ignorance leading to inaction. Sequential models for each agent type are specified, and their results compared to empirical studies. It is concluded that only the Hesitator model produces reasonable results.

Aggregated Beliefs and Informational Cascades

In the 1992 paper [1] Bikchandani et al. show how it may be rational for Bayesian agents in a sequential decision making scenario to ignore their private information and conform to the choices made by previous agents. If this occurs, an agent ignoring her private information is said to be in a cascade.

Model Transformers for Dynamical Systems of Dynamic Epistemic Logic

This paper takes a dynamical systems perspective on the semantic structures of dynamic epistemic logic (DEL) and asks the question which orbits DEL-based dynamical systems may produce. The class of dynamical systems based directly on action models produce very limited orbits. Three types of more complex model transformers are equivalent and may produce a large class of orbits, suitable for most modeling purposes.

Convergence, Continuity and Recurrence in Dynamic Epistemic Logic

The paper analyzes dynamic epistemic logic from a topological perspective. The main contribution consists of a framework in which dynamic epistemic logic satisfies the requirements for being a topological dynamical system thus interfacing discrete dynamic logics with continuous mappings of dynamical systems. The setting is based on a notion of logical convergence, demonstratively equivalent with convergence in Stone topology. Presented is a flexible, parametrized family of metrics inducing the latter, used as an analytical aid. We show maps induced by action model transformations continuous with respect to the Stone topology and present results on the recurrent behavior of said maps.

Hintikka’s Knowledge and Belief in Flux

Hintikka’s Knowledge and Belief from 1962 is considered the seminal treatise on epistemic logic. It provides the nuts and bolts of what is now a flourishing paradigm of significance to philosophy, economics, mathematics and theoretical computer science—in theory as well as practice. And in theory and for practice epistemic logic has been extensively articulated, refined and developed especially with respect to capturing the dynamics of reasoning about knowledge. But although the robust narrative about Hintikka’s epistemic logic is rather static, the leap to dynamic epistemic logic is right there back in 1962 as this paper will show.

Pristine Perspectives on Logic, Language and Computation : ESSLLI 2012 and ESSLLI 2013 Student Sessions, Selected Papers

The European Summer School in Logic, Language and Information (ESSLLI) is organized every year by the Association for Logic, Language and Information (FoLLI) in different sites around Europe. The main focus of ESSLLI is on the interface between linguistics, logic and computation. ESSLLI offers foundational, introductory and advanced courses, as well as workshops, covering a wide variety of topics within the three areas of interest: Language and Computation, Language and Logic, and Logic and Computation. The 16 papers presented in this volume have been selected among 44 papers presented by talks or posters at the Student Sessions of the 24th and 25th editions of ESSLLI, held in 2012 in Opole, Poland, and 2013 in Dusseldorf, Germany. The papers are extended versions of the versions presented, and have all been subjected to a second round of blind peer review. (Less)