Despite its popularity, model theory based on Tarski's insights is in need of deeper philosophical reflection. A wide range of stances towards it was proposed, some seeing it as project based on fundamental misconceptions, some asserting it reveals the very essence of logic.
I would like to balance these extreme views. Of particular importance will be its connection to the problem of logical constants.
Identifying logical constatnts enables us to identify logical forms of statements and thus brings us close to demarcating logic. We will see that solving this issue in ways suggested by model theory has its considerable costs, while the gains are rather modest.