I formulate a theory of groups based on pluralities and counterparts: roughly put, a group is a plurality of entities at a time. This theory comes with counterpart-theoretic semantics for modal and temporal sentences about groups. So this theory of groups is akin to the stage theory of material objects: both take the items they analyze to exist at a single time, and both use counterparts to satisfy certain conditions relating to the modal properties, temporal properties, and coincidence properties of (...) those items. (shrink)

Many philosophers maintain that an adequate metaphysical theory of social groups (e.g., baseball teams, rock bands, committees, and courts) will be one that is capable of accommodating social groups that may exist despite having no members. In this paper, I examine cases that motivate this position, cases where a social group seems to persist at some time despite having no members at that time. My aim here is twofold. First, I aim to show that we may accept that these motivating (...) cases are indeed possible without accepting that some social groups may exist despite having no members; second, I aim to show that the acceptance of the possibility of memberless social groups comes at a steep, theoretical cost. In particular, I will argue that the acceptance of memberless social groups comes at the cost of effectively preventing them from being the kinds of things that may interact with the material world. (shrink)

The folk conception of money as an object is not a promising starting point to develop general, explanatory metaphysical accounts of the social world. A theory of institutions as rules in equilibrium is more consistent with scientific theories of money, is able to shed light on the folk view, and side-steps some unnecessary puzzles.

Material objects extend through space by having different spatial parts in different places. But how do they persist through time? According to some philosophers, things have temporal parts as well as spatial parts: accepting this is supposed to help us solve a whole bunch of metaphysical problems, and keep our philosophy in line with modern physics. Other philosophers disagree, arguing that neither metaphysics nor physics give us good reason to believe in temporal parts.