Project Summary

The Logical Structure of Correlated Information Change

The standard logical approaches to rational belief revision or scientific theory change assume either that the reality under investigation is static or at least that any ontic changes are not directly correlated with the doxastic/epistemic change happening at the same time. But in numerous situations, the very act of learning new information may directly change the reality that is being learnt. An example is the way in which an introspective agent changes her beliefs when learning new higher-order information, i.e. information that may refer to her own beliefs. A similar situation arises when a scientist learns about a phenomenon by performing measurements that perturb the very phenomenon under study. In quantum mechanics, this property that “observation causes perturbation” (the so-called observer effect) lies at the basis of most practical applications in quantum communication. But similar examples can be found in social sciences, economics and psychology: in these areas, an “experiment” (e.g. the performing of a psychological test, the way an interview or a poll are conducted, the way statistical data are gathered) or the adoption of a theory (e.g. an influential social-economic theory) may change the very facts under investigation. More complex such scenarios of correlated information change occur in groups of communicating agents, whenever some agents’ beliefs about the others’ belief changes may trigger or influence their own belief change.

In this project we propose to develop a unified logical setting to handle these various types of correlated information change in a multi-agent context. The proposed setting is based on bringing together insights, concepts and methods from Dynamic Epistemic Logic, (Dynamic) Quantum Logic, Belief Revision theory, Truth Approximation theory and Learning Theory. Particular types of correlated information change were previously studied in Physics (Quantum Mechanics), Economics (Game Theory), Social Sciences and Epistemic Logic, but without having a general logical setting and without any connection to the logic of scientific theory change. We plan to explore applications of the proposed logical framework to various areas of Philosophy, ranging from Social Epistemology to Philosophy of Science and Philosophy of Information. In particular, we plan to use it to develop a new approach to scientific theory change. Within philosophy of physics, our aim is to apply our general setting to develop an epistemological-informational understanding of quantum information and its flow. Within social epistemology, we plan to use the proposed setting to formalize and give a logical analysis to puzzling social-informational phenomena such as the tragedy of the commons, informational cascades and the epistemic bandwagon effect.