From Shared Evidence to Group Attitudes

• Applicant: Professor Dr. Olivier Roy
• Subject Area: Theoretical Philosophy
• Term: from 2016 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 282669151

Complex, coordinated efforts such as organizing national intelligence, rescuing flood victims, or conducting large-scale scientific research require both pooling and sharing information. These two processes are related but different. A commanding officer may pool intelligence and be able to locate a target while an agent in the field is unable to do so. The fact that the intelligence is not shared, or 'out in the open' for all field officers, might even be crucial to the success of the operation. What is, then, the precise relationship between pooling and sharing information? Is shared information always pooled? How can individuals with limited time and resources effectively share and/or pool the information they have? These questions have attracted a lot of attention in philosophical logic, but up to now the answers rest heavily on idealizations. Agents in these models are 'logically omniscient', i.e, they know all the logical consequences of their information. So in these models pooling is just a matter of putting together all the information of each agent. But in general reaching the right conclusions from pooling might not be trivial at all. Standard logical models also assume that the agents can store highly complicated notions, for instance an unbounded number of iterations of 'everybody knows that everybody knows that...', which are at the heart of the definition of so-called 'common knowledge.' This project will lift these idealizations and study sharing and pooling for agents with limited cognitive and inferential capacities. We will develop notions of shared information, e.g. common knowledge, for agents who do not have the full deductive power of classical models, and will use tools from the theory of judgment aggregation and belief merging to develop new logical models of information pooling for non-ideal agents. Finally, we will study how information dynamics in groups, and in particular the dialectics of questions and answers, can foster or prevent both pooling and sharing. The project will build on the work of an existing and rather successful Czech-German team of philosophical logicians. The team has been working on plausible models of the dynamics of knowledge and beliefs for resource-bounded individuals for some years now. The proposed research, focused on group information, is a natural next step.

• DFG Programme: Research Grants
• International Connection: Czech Republic, France, Norway
• Partner Organisation: Czech Science Foundation
• Co-Investigators: Dr. Norbert Gratzl; Dr. Ondrej Majer; Michal Pelis; Adam Prenosil; Vit Puncochar; Dr. Igor Sedlar
• Cooperation Partners: Dr. Marta Bilkova; Professor Dr. Umberto Grandi; Dr. Gabriella Pigozzi; Professor Dr. Thomas Ågotnes