Matthieu Gallais (University of Lille): “A Modal Epistemology of Scientific Models: Structures, Make-Believe and Properties”

Abstract: The modal epistemology I develop aims to describe how scientific models and target systems are related by comparing theoretical properties with world-lines, that is to say to epistemic constructions across possible situations. I suggest that what must be considered as remaining the same from models to real systems is the properties, rather than the structures. As I will explain, conventional structuralism on its own is not enough to relevantly study the relation between models and target-systems. However, one of the major issues in my project is that the same property can be exemplified in different ways: sometimes perfectly so, sometimes approximatively. Then, how to study the identity of a property in modal contexts? My approach should be considered as a fictional one because its starting point consists in comparing scientific models to works of fiction and because it uses the notion of games of make-believe. But on the other hand, instead of considering the existence of a unique fictional model-system, I suggest that a model is about different kinds of situations compatible with it. That is why modal logic is useful to understand the applicability of models, notably by analysing the identity of properties across possible worlds.