04 June 2019

Hanna Sofie Van Lee has defended her Ph.D. thesis

Congratulations to Hanna Sofie Van Lee who successfully defended her Ph.D. thesis on Maj 17. 2019.

Hanna was the very first Ph.D. fellow at C.I.B.S. She started her Ph.D. project in November 2015. at the same time as C.I.B.S. was established. 
We all wish her good luck with future endeavors.

Title: 
Logical Perspectives on Informational Social Influence in Trade and Science

Abstract 
The Ph.D. thesis studies two concrete social phenomena where information and in particular higher-order information play a key role: 1. Scientists who acquire knowledge and belief through observation and interaction 2. 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: 1. A representation theorem for one particular family of information update models 2. 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.

Assessment Committee

• 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)

Pictures from the defence