Role-Player Realism

In practice theoretical terms are open-ended in not being attached to anything completely specific. This raises a problem for scientific realism: If there is no one completely specific kind of thing that might be in the extension of “atom”, what is it to claim that atoms exist? A realist’s solution is to say that in theoretical contexts of mature atom-theories there are things that play the role of atoms as characterized in that theory-context. The paper closes with a laundry list of problems that this more careful statement of scientific realism still faces.