Last week, Sara Bernstein (Duke) made Roberta Ballarin (University of British Columbia) it. Who’s Ballarin going to tag? Let’s find out…

Atomicity is the thesis that everything is ultimately composed of atoms, entities that lack proper parts. Atomicity is standardly defined as “for every x there is a y such that y is an atom and y is a part of x”, i.e. everything has an atom as a part. But does this definition really capture atomicity? In a recent paper in Philosophical Studies, “How do you say ‘everything is ultimately composed of atoms’?”, Anthony Shiver (University of Georgia) presents a countermodel to this definition. According to Shiver, the model he presents satisfies the definition, since every object in the model has an atom as a part. Yet it is not true that everything is ultimately composed of atoms, since every composite object in the model has also a composite part. Shiver proceeds to present his own definition of atomicity—“Everything is a part of a sum of atoms”—that is not subject to the same problem. Anthony Shiver, you’re it!