Logical Perspectives on Informational Social Influence in Trade and Science
Public Defence of PhD thesis by Hanna Sofie van Lee.
The Ph.D. thesis studies two concrete social phenomena where information and in particular higher-order information play a key role:
- Scientists who acquire knowledge and belief through observation and interaction
- Traders who reason about asset values and about other traders. Using the machinery of dynamic epistemic logic (DEL) the thesis formulates and structurally analyses opinion diffusion in scientific communities and so-called greater fools reasoning in trade markets – one important mechanism used in the explanation of financial bubbles.
In particular, the thesis focuses on informational social influence: People are under informational social influence when they accept information obtained from someone else as evidence about reality.
Alongside these applied analyses, the thesis also makes two contributions that are more theoretical:
- A representation theorem for one particular family of information update models
- A philosophical reflection on the method of logical modelling used in the rest of the thesis.
I argue that epistemic logic is a natural and expressive framework to study informational social influence, as epistemic logic allows abstracting away from irrelevant details and at the same time focus on informational content of social influence such as higher-order reasoning and information change. The thesis thereby shows that an epistemic logical study provides a novel perspective on well-known problems of informational social influence.
- Professor Anders Rahbek, Chairman (University of Copenhagen)
- Professor Barbara Osimani (Polytechnic University of the Marche)
- Professor Olivier Roy (Universität Bayreuth)
Moderator of defence
Professor Nils Holtug (University of Copenhagen)
Copies of the thesis will be available for consultation at the following three places: at the Information Desk of the Library of the Faculty of Humanities; in Reading Room East of the Royal Library (the Black Diamond), and at the Department of Media, Cognition and Communication, Karen Blixens Plads 8.